Vegetarian
Feline Diets
http://tinyurl.com/vegepets-cat-diets
Andrew Knight BSc. (Vet. Biol.), BVMS, CertAW, MRCVS
Veterinarian
Updated: 13 Jul. 2008
CONTENTS
1. Introduction
3. Evolutionary adaptations to a carnivorous diet
4. Requirements of vegetarian diets
5. Palatability
10. Natural behavior
11. Health benefits of vegetarian diets
12. Conclusions
Appendix I: Nutritionally inadequate vegetarian diet produces malnutrition: A case study
Appendix II: Inadequate quality control in feed production: A case study
The enormous death and suffering inflicted upon approximately fifty billion chickens, pigs, sheep, cows, and other animals, both intensively and extensively farmed, who are slaughtered annually, and upon millions of intensively farmed or wild-caught fish, in order to fulfill the desire of some human beings for meat, has been thoroughly documented; as have the deleterious environmental impacts of both intensive and extensive animal farming (www.VeganOutreach.org provides extensive, thoroughly-referenced information on these issues).
It is because of the ethical concerns of a growing population of vegetarian animal guardians, and because of medical conditions such as allergies which are caused by beef, lamb and other meat-based dietary ingredients, that vegetarian pet food brands were first developed. However, feline vegetarian diets remain the subject of considerable controversy, which is exacerbated by widespread ignorance of the health and nutritional issues involved, including among veterinarians and other experienced animal carers.
To assist animal guardians, animal carers and veterinary personnel who wish to gain a sounder understanding of these issues, the following examines the evolutionary adaptations of cats that equipped them for a carnivorous diet in their original environments; the palatability, nutritional and bioavailability requirements of vegetarian feline diets; the need for quality control of vegetarian feline diets; prevention of urinary alkalinization, blockages and infections, to which a small percentage of vegetarian cats are predisposed; the relevant natural behavior of cats; and the health benefits commonly observed in cats upon switching to a nutritionally sound vegetarian diet.
Perhaps the most famous vegetarian ‘cat’ in America was an orphaned lioness named Little Tyke. Raised by Georges and Margaret Westbeau in the 1950s with a menagerie of other rescued animals, including a lamb, deer and swan, all of whom became her friends, Little Tyke resisted all attempts by the Westbeaus to feed her meat. She would refuse milk with even a single drop of blood mixed in (Westbeau, 1986).
African lions possess short, powerful jaws and have skulls highly adapted to killing and eating natural prey such as gnus, zebras, gazelles, impalas, and giraffes. Made desperate by veterinarian claims Little Tyke would become severely ill without meat, the Westbeaus posted a $1,000 reward for anyone who could find a way to entice her to eat meat. In the meantime meals consisted of a double handful of cooked grains, chosen for their high protein content and their calcium, fats, and roughage, along with a half gallon of milk and two eggs. Little Tyke refused bones, so to safeguard the health of her teeth and gums, the Westbeaus supplied rubber boots sprinkled with perfume, to which she was attracted. One boot lasted almost a month (Westbeau, 1986).
At four years of age, this mature African lioness weighed 352 pounds. Her body stretched 10 feet 4 inches long and could run 40 miles per hour. One of the country’s most able zoo curators said Little Tyke was the best of her species he had ever viewed. She had shown no signs of dietary deficiency, so the Westbeaus finally stopped trying to feed her meat, and finally ceased worrying about what their veterinarians had told them. She eventually died of viral pneumonia contracted during a stressful episode of television filming (during which she licked day old chicks and played with lambs, a kitten, and the producers seven year old daughter), conducted during a heat wave (Westbeau, 1986).
To date, hundreds of more conventionally-sized cats have successfully been maintained, some for many years, on a vegetarian diet. Numerous accounts of these cats exist on the websites of the vegetarian pet food suppliers and in the additional resources listed under ‘Resources and Suppliers.’
Some animal shelters also use them, which is particularly interesting, given the potential to observe the dietary effects in large population. Stan Petrey (1998), cofounder and executive director of the Home At Last animal shelter in Kentucky, explained the philosophy underlying their choice to use vegan food (containing no milk, eggs or other animal products) for their population of 70-80 dogs and cats, and the observed effects on the animals’ health:
“A philosophical debate is raging in the animal rescue community as groups seek to come to terms with the concept of “no-kill” shelters. Questions usually focus only on the fate of the homeless cats and dogs; what is often absent from the discussion are the numbers of murdered “farm” animals fed to shelter animals. Perhaps the definition of “no-kill” varies according to which species are considered companions. The rescue of one species at the expense of another contradicts our definition of “sanctuary.” Using cruelty-free food is at the heart of Home At Last’s mission, a challenging but not impossible task. The implementation of a vegan diet for the various Home At Last residents has varied according to species. The dogs adapted quickly and willingly to vegetarianism…The first meal of all newly rescued dogs is now vegan. The dogs display every sign of good health. They are energetic, yet emotionally balanced. Cool heads are important because our dogs live in quasi-natural environments, with small packs in huge enclosures. Some dramatic health improvements may be attributed to the diet…The changeover process for cats involves mixing a meat kibble and canned food with a homemade recipe. After several days of this, the evening meal is changed to a vegan combination of textured vegetable protein, Vegecat supplement, squash, sweet potatoes, nutritional yeast, oil, and vegetable broth…One of our cats, McBane, required surgery and bowel obstruction and experienced frequent stomach upsets before becoming vegetarian. McBane’s dramatically improved bowel and urinary function since the change is encouraging; after one year on plant food, he’s never appeared healthier of happier. In fact, no diet-related problems have appeared in any of the cats, whose vegetarian status ranges from one year to four months. As we move deeper into this project, skeptical questions can be answered with greater confidence. Doubters claim that our idealism is unfairly making dietary slaves of the animals. “This isn’t their natural food” is an often-used retort. But is a bag of “rendered surprise” the natural diet of a dog or cat? … Hopefully, more veterinarians will rethink the baseless rejection of vegetarian diets for cats and dogs. Beth Johnson, D.V.M., recently remarked, “The Home At Last dogs and cats appear in excellent physical condition. The dogs are enthusiastic with vibrant coats and show no evidence of nutritional deficiencies. The cats, who are kept indoors, also appear very healthy without any evidence of nutritional deficiency.””
3. Evolutionary adaptations to a carnivorous diet
Dogs may be biologically classified as omnivores, due to their ability to subsist on a mixed diet of animal and plant-based material in their natural environments. In contrast, cats are classified as obligate carnivores, because their evolutionary anatomical, physiological and biochemical adaptations to a carnivorous lifestyle prevent them from deriving substantial benefit from the available plant-based material in their natural environments. Both wild cats and dogs do consume plant material, primarily sourced from the gastro-intestinal tracts of their consumed prey.
While the nutritional limitations of natural environments are irrelevant to animals maintained on artificial meat, plant, mineral and/or synthetically-based diets, as almost all domesticated cats and dogs are, the evolutionary adaptations that maximized the survival efficiency of cats in their natural environments nevertheless remain of interest to some, and are summarized in the following.
Taste perception
Cats appear to have lost the receptors that allow omnivores and vegetarians to enjoy the taste of sugars or medium chain fatty acids (Kirk et al., 2000), which are more common in plant-based than animal tissue.
Teeth
The canines and incisors of cats are designed to grip prey, and to slice tissue. Cat teeth are less suited than those of dogs for grinding plant material, as indicated by their fewer premolars and molars, and their lack fissured crowns (Kirk et al., 2000).
Gastrointestinal length
The extra digestion time required for plant-based material, and consequent increased gastrointestinal length, was not required for evolving cats; hence their gastrointestinal tracts are shorter than those found in dogs (Kirk et al., 2000).
Digestive enzymes
Cats partially or completely lost, or failed to develop, the ability to secrete certain enzymes used to digest sugars (Kinezle, 1994) more likely to be found in plants, and to vary the composition of their digestive enzymes with dietary changes (Baker & Czarnecki-Maulden, 1991). Digestion of complex molecules into simpler ones is a prerequisite for intestinal absorption. For example:
Cats lack salivary amylase. Amylase catalyses the hydrolysis (digestion) of starch (a complex sugar used by plants to store energy) into simpler compounds (Blood & Studdert,1988).
The pancreatic and intestinal amylase activities of cats are five and ten percent respectively of those found in dogs (Kirk et al., 2000).
Cat disaccharidases at the intestinal brush border are of decreased and relatively invariable activity levels when compared to dogs (Kirk et al., 2000). These enzymes split larger sugars into smaller ones.
Cats have very low glucokinase and absent fructokinase activity levels (Kirk et al., 2000). These enzymes allow animals to derive energy from these simple sugars. Fructose, in particular, is found primarily in honey and sweet fruits (Blood & Studdert,1988). Instead cats derive most of their energy from protein sources.
Protein requirements
Cats have very high protein requirements because they rely predominantly on protein to meet energy requirements. They rely upon the enzyme transaminase to convert alpha-amino acids (protein digestion products) into alpha-ketoacids for energy production via the biochemical Kreb’s cycle, or for use as a gluconeogenic substrate (allowing the creation of glucose, a universal cellular energy source). The activity of transaminase is greater in cats than in dogs, and is invariable (Kirk et al. 2000, MacDonald et al. 1984).
Waste excretion
The urea cycle converts nitrogenous wastes resulting from protein breakdown during energy production into soluble urea, ready for excretion. Unlike dogs and other omnivores, cats are unable to vary the activity level of their urea cycle enzymes in response to dietary variations. Their continuous activity protects against the adverse effects of hyperammoniaemia which would otherwise be an inherent risk of a high protein diet (Kirk et al., 2000).
4. Requirements of vegetarian diets
Whatever combination of animal, plant, mineral or synthetically-based ingredients are used, diets should be formulated to meet the palatability, nutritional and bioavailability requirements of the species for which they are intended.
The well-known fixation of cats in particular to meat-based commercial brands to which they have become accustomed is primarily due to the addition of ‘digest,’ the industry euphamism for partially digested chicken entrails. According to Small Animal Clinical Nutrition, “Digest is probably the most important factor discovered in recent years for enhancing the palatability of dry food for cats and, to a lesser degree, dogs.” (Lewis et al., 1987). Considerable patience and persistence may be required when altering the diets of cats who have been exposed to digest long-term.
Cats vary widely in their dietary flexibility. In order to transition some cats onto a vegetarian diet, it may first be necessary to withhold all food (not water!), for one day. This will stimulate the appetite without harming the cat. It is always advisable to change the diet gradually, e.g. by using 90 % old and 10 % new diet for a few days, then switching to 80 % and 20 % for a few more days, thereby transitioning to the new diet over several weeks, or even longer if necessary. A gradual change is more acceptable behaviorally, and also allows an appropriate transition of digestive enzymes (to the extent possible) and intestinal flora (bacteria), thereby minimizing the chance of gastrointestinal reactions such as diarrhea.
Cat guardians should demonstrate by their behavior that they consider the new diet just as edible as the old (without possibly warning or alarming the cat by making a fuss). They should not be concerned if their cat eats around the vegetarian food at first; just having it in close proximity to the other food will help the cat make the necessary mental association. Mixing the food thoroughly may help, as may the addition of odiforous (the sense of smell is very important) and tasty additives, such as nutritional yeast, vegetable oil, nori flakes and spirulina. Gently warming the food may also help. Guardians should remove uneaten food and offer only fresh food.
The most important factors for difficult cats are gradual change and persistence. Using these principles, the most stubborn of cats have been successfully weaned onto healthy vegetarian diets. Vegetarian cat food recipes may be obtained from Peden (1999) and Gillen (2003) and from suppliers www.VegePet.com and www.VeganCats.com.
In Vegetarian Cats & Dogs, Peden (1999) recounts numerous stories of healthy vegetarian cats who have come to love their diets. New Zealander Ann Fullerton states of her Siamese, Melaney: “Despite the fact only vegetarian food is available from us, no cat has ever deserted us for a home where the menu is more to their taste.”
Grayson the tom cat also judged the palatability of vegetarian cat food more than acceptable: “His owners put him outside winter nights because they have a baby. Though we don’t have snow, winters here are still chilly. It didn’t take Grayson long to discover our cat door is left permanently ajar for Ossie’s benefit. And that chairs and laps by the woodburner are warmer than sleeping under our house. But he is too big to easily squeeze through the cat door. Thumps and clatterings from the laundry always signal Grayson is gamely fighting his way in, one massive shoulder at a time — luckily the door is sturdy! The endearing thing about him is the way he loves vegetarian cat food. What are you to do with a cat that literally squeaks with joy at the prospect of “Vegecatised” cat porridge? — then bolts every mouthful, purring loudly? His owners complain Grayson has lost interest in his meat. So I’ve stopped giving him the vegetarian breakfast he politely requests after a night at our place. Instead he’s firmly but regretfully sent home out of fairness to his owners. I’ve also stopped giving him tea. Nothing daunted, he now turns up for a vegetarian morning tea and supper! It does look as if he wants to move in with us, but ethics aside (he does have a good home) we couldn’t afford to care properly for such a big animal. But he’s a very welcome visitor.”
Alfredo Kuba of Mountain View, California, demonstrated the full range of feline fussiness when describing his two male rescued stray cats Mussi (castrated at 2 months of age) and Tommy (castrated when rescued at around 3 years of age) (Kuba, 2004):
“My experience is that animals can adapt to a vegan [pure vegetarian] diet well, it is just a matter of being patient and experimenting with combinations of flavors until you find what they like. Mussi loved the food even though it took about 5 or 6 months of experimenting with vegan recipes to get him to gradually adjust to his new diet. I switched him to a vegan diet after he became ill with diabetes at the age of three on commercial pet food. His diabetes greatly regressed and he finally passed away at the age of 17 after 14 healthy years on a vegan diet. We just rescued and adopted another stray cat we named him Tommy. We started him immediately with Evolution vegan food and we didn't have to get him to adjust to it, he loved the food from the get go!”
To safeguard health, vegetarian diets must be complete and balanced with respect to all essential nutrients. This may be achieved by feeding a vegetarian nutritional supplement or complete commercial diet certified on the label as meeting the nutritional standards of the US Association of American Feed Control Officials (AAFCO).
The Committee on Animal Nutrition, reporting to the Board of Agriculture within the US National Research Council (NRC), has developed nutritional standards for at least 15 species. Historically AAFCO used the NRC recommendations, but in 1993 began publishing its own expanded nutrient requirements, which are now widely recognized as the required nutritional standards for animal feeds.
In order to meet AAFCO nutritional requirements, manufacturers of vegetarian (and, in some cases, processed meat-based diets), diets rely upon vegetable, mineral and synthetic sources of nutrients normally derived from animal tissues.
The following nutrients are of particular importance to cats maintained on vegetarian diets, as they are scarce in the plant material available in the cat’s natural environment, and are naturally sourced from small mammals, birds and insects:
Protein
Cats are biochemically dependent on protein as a primary energy source, and consequently have a very high dietary protein requirement.
Of the 23 different amino acids, 11 are considered essential in the cat’s diet (Gillen, 2003). The following require alternative supplementation if quality meat is not provided:
Taurine
This sulfur-containing beta-amino acid occurs at low levels in plant material. For reasons of economy commercial petfood manufacturers have for many years used synthetic, rather than animal, sources of taurine. The same source is used by vegetarian pet food manufacturers.
Taurine is particularly required by cats for several reasons (Baker & Czarnecki-Maulden 1991, Blood & Studdert 1988, Gray et al. 2004, National Research Council 1986, Palackal et al. 1986, Peden 1999):
· Taurine synthesis occurs in the liver at a relatively low rate in cats.
· Unlike other species, cats are unable to synthesize taurine from amino acids cysteine and methionine.
· Within the intestinal lumen, microbial degradation further increases taurine loss.
· Most mammals make bile salts (as taurocholic acid) from both taurine and glycine, however cats can only use taurine for taurocholic acid synthesis.
· Feline taurine deficiency can result in multiple organ system dysfunction, the effects of which have been described by numerous investigators. Effects include generalized retinal atrophy, developmental deficits of the visual cortex and cerebellum, dilated cardiomyopathy, reproductive failure and thromboembolism. Normal growth, immune and neurological function are all dependent on adequate taurine levels.
Typical retinal degeneration (atrophy of the rods and cones) in adult cats or older kittens causes only partial loss of vision, except in advanced cases. Without a dietary source of taurine, cats exhibit evidence of retinal changes in as little as three months. These changes become extensive within six months and total blindness may take two years to develop. If treated with supplementary taurine in time, degeneration is reversible.
The entry of calcium into the myocardium in order to trigger each heart beat is regulated by taurine. Deficiency results in cardiomyopathy. Cats with this degenerative disease typically live only a few days to weeks after diagnosis, with death resulting from myocardial flaccidity and impaired pumping ability.
Methionine and cysteine
These sulfur-containing amino acids less available in plant material, and are required in greater quantities by cats because they are highly utilized as gluconeogenic substrates (allowing the creation of glucose, a universal cellular energy source), in addition to cysteine’s roles in hair and felinine (an amino acid of unknown function) synthesis (Blood & Studdert 1988, Zoran 2002). Cats are unable to synthesize or conserve methionine, and deficiency can result in poor growth and dermatitis (an inflammatory skin condition) (Gray et al., 2004).
Arginine
Arginine is found in low levels in plant material, and cats are unable to synthesize its precursors. Arginine is an essential amino acid in the feline diet due to its function in the urea cycle. Deficiency can lead to hyperammonemia and hepatic encephalopathy, poor growth and rapid loss of body mass (National Research Council, 1986).
Lysine
Lysine is required by cats and is normally limited in the diet when grain is the only major protein source. This essential amino acid is important in the formation of collagen, fibrin and keratin; hence deficiencies would result in skin and connective tissue deficits (Blood & Studdert 1988, MacDonald et al. 1984).
Arachidonic acid
This essential fatty acid found primarily in meat. Unlike dogs, cats lack the enzyme delta 6 desaturase and are consequently unable to synthesize arachidonic acid from linoleic acid (National Research Council, 1986). Arachidonate is crucial for the biosynthesis of some prostaglandins, which have a variety of potent biological activities of a hormonal or regulatory nature. Arachidonate deficiency results in listlessness, reduced feed conversion efficiency and poor growth, enlarged, fatty livers, mild mineralization and fatty infiltration of the kidneys, dry hair coat, scaly skin and dandruff, inflammatory skin lesions, immune suppression and, paradoxically, higher lymphocyte production. Cats lacking dietary arachidonate can experience prolonged bleeding times due to delayed and weak platelet aggregation. The most sensitive indicator of arachidonate deficiency is reproductive failure in female cats (MacDonald et al., 1984).
Vitamin A
Unlike some other species, cats are unable to synthesize vitamin A (retinol) from beta-carotene in the intestinal mucosa, hence retinol must be provided pre-formed in a cat’s diet (Gray et al., 2004). Deficiency can lead to blindness, dermatological lesions, secondary infections, and reproductive problems (National Research Council, 1986).
Fish liver oils supplied vitamin A until 1941 when war orders banned fishing vessels from the Pacific, and chemists learned to synthesize it out of necessity. By 1966, production of synthetic vitamin A totaled over 830 tons in the USA (Peden, 1999).
B Vitamins
B vitamins are not conserved in cats (Gray et al., 2004). Cobalamin (a cobalt-containing complex common to all B12 vitamins) is produced by microbes and is scarce in plants. Deficiency may result in poor growth and neuropathies (Kirk et al., 2000). Commercial production of vitamin B12 uses the synthesizing ability of bacteria such as streptomycetes.
Niacin (a water soluble B complex vitamin) is less available in plant tissue, and unlike some other species, cats are unable to synthesize significant levels of niacin from tryptophan. Deficiency manifests in diarrhea, anorexia, weight loss, weakness and apathy. Thick saliva with a foul odor is characteristic, as well as ulceration of the upper palate. An association with respiratory disease is common, contributing to early death (MacDonald 1984, Blood & Studdert 1988).
Pyridoxine (Vitamin B6) is a component of transaminases, and is needed in relatively high quantities by cats due to their increased protein catabolism (Gray et al., 2004). Deficiency manifests as cardiac dilatation, congestion, deterioration of the peripheral nerves, convulsive seizures, and irreversible kidney lesions (National Research Council, 1986; 26).
Others
Additional nutrients that must be supplied in the correct proportions but which are of less concern in vegetarian animal diets include overall energy, carbohydrates, L-carnitine, calcium, phosphorus, magnesium, iron, copper, zinc, selenium, potassium, sodium, chlorine, iodine, vitamins C, D, E, thiamin (vit. B1), riboflavin (vit. B2), pantothenic acid, folic acid, biotin, choline, linoleic acid, and water (Peden, 1999).
The bioavailability of nutrients (extent to which they are available to the tissues) is determined largely by their level of digestibility into simple molecules capable of absorption through the intestinal mucosa. The importance of digestibility is increased in animals such as cats and dogs that have relatively short intestinal tracts. Fortunately, studies have demonstrated ample digestibility of vegetarian dietary ingredients in cats and dogs.
Pencovic and Morris (1975) studied the apparent digestibility of starch (added at 35 % of diet dry matter) found in corn or wheat grain. Apparent starch digestibilities for coarsely ground, finely ground, or coarsely ground and cooked grains were: corn, 79, 94, and 88 %; and wheat, 92, 97, and 96 % respectively. It was concluded that starch from corn and wheat, especially when finely ground, is well utilized by the cat (National Research Council, 1986; 6).
The digestibility of some sources of protein has been evaluated in the dog. Hegsted et al. (1947) found that the apparent digestibility of proteins in an all vegetable diet containing white bread, corn, rice, potatoes, lettuce, carrots, onions, tomatoes and applesauce was 80.0 (plus or minus 7.7 %). James and McCay (1950) reported that the apparent protein digestibility of commercial, dry-type food, containing both vegetable and animal proteins, ranged from 67 to 82 % for adult dogs. Kendall and Holme (1982) reported the apparent crude protein (Nx6.25) digestibility coefficients for textured soy protein, extracted soy meal, full-fat soy flour, and micronized whole soybeans ranged from 71 to 87 %. Moore et al. (1980) reported apparent digestibility values of soybean meal, corn, rice, and oats by mature Pointers to be in the range of 77 to 88 %. Their data revealed that normal cooking procedures did not significantly influence the digestibility of rice, oat, or corn protein. Their data also indicated that increasing the fat content of the diet from 10 to 20 % did not alter the digestibility of nitrogen in a corn-soybean-based diet. Burns et al. (1982) showed that the apparent digestibilities of lactalbumin, casein, soy protein, and wheat gluten are 87, 85, 78, and 77 %, respectively (National Research Council, 1986; 12).
Pet food manufacturers are well aware of the acceptable digestibility of plant-based ingredients, which make up a large proportion of the products they sell.
Two studies have clearly demonstrated nutritional inadequacies in commercially available brands of vegetarian cat or dog food. Kienzle and Engelhard (2001) found that common deficiencies of European vegetarian cat and dog foods included sulfur containing amino acids, taurine, vitamin D, vitamin B12, arachidonic acid, and trace minerals. Gray et al. (2004) found that two American vegetarian cat food brands were deficient in select amino acid composition, trace minerals, vitamins, and arachidonic acid. One was deficient in overall protein content. These deficiencies occurred contrary to the expectations of the manufacturers and contrary to the nutritional information supplied on the labels. Such deficiencies clearly demonstrate the need for manufacturers to implement good quality control procedures, including regular laboratory nutritional analysis. To encourage this process, interested consumers could request copies of recent independent laboratory nutritional analysis results from manufacturers.
The excretion of the nitrogenous waste products of protein catabolism results in the acidic urine of carnivores. Vegetarian diets with their decreased protein content result in urinary alkalinization. The pH (acidity) alterations predispose to the crystallization of urinary salts, resulting in the formation of stones in the urinary system (urolithiasis), which may result in feline urological syndrome (FUS): partial or complete urinary obstruction (which may be life threatening), dysuria (difficulty in urinating) and haematuria (blood in the urine) (Blood & Studdert, 1988). Alterations in bacterial flora, with increased possibility of urinary infections, may also result.
The likelihood of alkalinization, urolithiasis, FUS and urinary tract infections may be minimized via several means:
Minimizing magnesium content
By far the most common urinary stone (urolith) is struvite (magnesium-ammonium-phosphate) (Blood & Studdert 1988). Hence minimizing urinary magnesium concentrations minimizes struvite formation. Ralston Purina’s flagship kibble contains 43mg/100kcalME (0.16 % magnesium on a dry matter basis). That pales in comparison to Puss’N Boots Tuna, which contains 84mg/100kcalME (0.25 % magnesium on a dry matter basis). Hill’s Prescription Diet c/d contains a far healthier 15mg/100kcalME (0.07 % magnesium on a dry matter). Vegecat KibbleMix for cats contains 19mg/100kcalME (0.07 % magnesium on a dry matter) (Peden, 1999).
Water consumption
Urinary salt concentrations can also be lowered by increasing the volume of water drunk and excreted. Clean, fresh water should always be available, and salty foods or a pinch of salt added to normal wet food are of benefit in stimulating thirst.
Urinary acidifiers
The normal pH of cat urine is 6.0-6.5, with struvite requiring 7.0 or higher to crystallize (Gillen, 2003). Urine may be acidified in several ways.
Asparagus, peas, brown rice, oats, lentils, garbanzos, corn, Brussels sprouts, lamb’s quarters (the herb Chenopodium album, also known as pigweed), most nuts (except almonds, coconuts and macadamia nuts), grains (not millet), and wheat gluten (used in kibble recipes) may be included in vegetarian cat food, and are all urinary acidifiers (Peden, 1999).
Vitamins are also of benefit. Vitamin C (ascorbic acid) is a urinary acidifier. Tablets may be pulverized or ascorbic acid powder may be used. The BSAVA (British Small Animal Veterinary Association) Small Animal Formulary (drug handbook) recommends a dosage of 50-80 mg/kg every 24 hours for cats and dogs (Tennant, 2003). In his Very Health Cat Book (Belfield & Zucker, 1983) veterinarian Dr. Belfield recommends 500-750 mg of vitamin C daily for healthy 10 pound adult cats, and 1000 mg for healthy queens and large cats or campaigning show cats. For cats with FUS he recommends 500-750mg of vitamin C in the morning and another 500mg in the evening for six months to resolve the problem. He states, “An animal may plug again in six weeks or so, but crystal formations become smaller and smaller and fewer and fewer.” pH buffering negates their effectiveness, so unbuffered Vitamin C should be used. If other urine acidifiers are also used, doses may be decreased.
Methionine is particularly effective in preventing struvite formation. Methionine is metabolized into sulfuric acid which is a powerful urinary acidifier. Additionally, sulfate displaces phosphate from the magnesium-ammonium-phosphate complex, preventing struvite formation. The BSAVA Small Animal Formulary recommends a dosage of 200 mg/cat every 8 hours (Tennant, 2003). The dosage should be adjusted to maintain urine pH at or below 6.5. Based on considerable experience, however, (Peden, 2003) states that a conservative dose for struvite dissolution is 1,000mg/day for a 10 pound cat, taken with meals, which should maintain urine pH between 6.1-6.2. Peden states that methionine supplementation should not exceed 1800 mg/day for a 10 pound cat. Excessive levels can result in metabolic acidosis with consequent loss of bony calcium and electrolyte imbalances. Methionine should not be used in young animals nor those with kidney or severe liver disease (Tennant, 2003).
Sodium bisulfate is a particularly powerful urinary acidifier, and is added to Vegecat pH (Peden, 2004). Ammonium chloride is also a powerful urinary acidifier, but may decrease palatability. In his "5-minute (veterinary) consult drug formulary," Papich (2004) recommends a dosage of 800 mg/cat (approximately 1/3 to 1/4 tsp of crystals) mixed with food daily.
Prevention
Based on his experiences with thousands of vegan cats Gillen (2003) states that 85-90 % of vegetarian cats do not require attention to dietary content; however, for the remaining 10-15%, urinary pH and dietary magnesium concentrations require monitoring. Given that the consequences of urolithiasis can be fatal blockage of the urinary system, particularly for males, to ensure safety, urinary pH levels of both males and females should be checked in the beginning, and at least fortnightly during transition to a vegetarian diet, and every 3 months thereafter, for life - even once diet and pH levels appear to have stabilized. Levels should be checked more frequently during any dietary, environmental or other changes with the potential to result in destabilization. Urine can be collected from cats using non-absorbent plastic cat litter available from veterinarians. pH test strips are also available from veterinarians, although pH meters provide the most accurate results. pH-indicating cat litter is also available, that changes color when exposed to alkaline urine (see Suppliers). However, this should only be used to supplement more accurate monitoring.
Gillen (2003) describes three steps, in increasing order of magnitude, that may be taken to rectify urinary alkalinization, if detected:
1. For minor cases, he states that enzyme supplements which include methionine, vitamin C, and/or cranberry extract will be sufficient. These limit both urinary alkalinization and inflammation. They also aid digestion, and can result in increased vitality.
2. For moderate cases, Gillen states that Vegecat pH, with added sodium bisulfate, may be sufficient.
3. For severe cases Gillen recommends methionine pills.
Opponents sometimes claim vegetarian diets violate cats’ rights to express natural feeding behavior, claiming that commercial meat-based diets represent a greater expression of that behavior. This claim most definitely warrants further scrutiny.
The natural hunting behavior of cats was directed towards a variety of small mammals, birds, and large insects found in the cat’s environment. Kills resulted in gorging of as much of the carcasses as possible to prevent consumption by competitors. These were followed by periods of hunger of uncertain duration.
The feeding patterns of normal domesticated cats are far removed from natural patterns. Cats fed commercial meat-based diets typically receive canned food at regular times once or twice daily, with dry kibble being available ad libitum (always). Commercial meat-based diets contain assorted animal body parts, slaughterhouse wastes, 4-D meat (from dead, dying, disabled or diseased animals), supermarket rejects, styrofoam packaging, large numbers of rendered dogs and cats from animal shelters, complete with detectable levels of euthanizing solution; old restaurant grease complete with high concentrations of dangerous free radicals and trans fatty acids; bacterial, protozoal, fungal, viral, and prion contaminants, along with their assorted endotoxins and mycotoxins; hormone and antibiotic residues; and dangerous preservatives (Knight, 2004).
As veterinarian Dr. David Jagger put it in the Vegepet Gazette, commercial meat-based diets involve:
“1) domesticating cats and preventing them from hunting their own food;
2) killing literally millions of chickens, cattle, sheep, horses, fish, etc., to feed domestic pets. It is hard to see how cats have a right to eat the flesh of animals such as those listed above, when this flesh would never form a part of a feral or wild cat’s diet. Moreover, since this flesh has often been condemned as contaminated or unfit for human consumption, deliberately feeding it to cats threatens their health and is closer to a violation of than a promotion of cats’ rights.”
Fish-based diets are frequently offered, despite their high levels of PCBs, heavy metals and other toxins (Knight, 2004), and despite the fact that fish are not a natural prey animal for cats. As Gillen (2003) aptly puts it, “Try this experiment: skip your cat’s breakfast one morning and bring him or her to the beach instead. Driven by hunger, what natural instincts might kick in? What are the chances that your cat will splash into the water, swim fifty or so miles out into the deep ocean, and there engage a 1200-pound animal (an adult tuna can be as large as a horse) in an underwater battle to the death in order to fulfill the natural feline diet of fish? The idea that fish is a natural food for cats is absurd.”
Saucers of milk are also frequently offered, despite the lactose intolerance of a significant proportion of cats. Other than by gulls and petrels, who drink elephant seal milk, and humans, who drink cow and goat milk, the drinking of milk by adults, much less of another species, is virtually unknown in nature, and is certainly unknown to cats. The obvious enjoyment of many cats of cows’ milk, fish, meat-based kibble, canned commercial diets, vegetarian diets and other foodstuffs naturally unavailable to them is no more a reflection of natural feeding behavior than is a child’s enjoyment of sweets, and, in some cases, no healthier.
In fact, cats prefer commercial cat food brands not because they perceive them as ‘natural,’ but because they have been conditioned by additives such as ‘digest,’ the industry euphemism for partially digested chicken and other entrails, to enjoy them. According to Small Animal Clinical Nutrition, “Digest is probably the most important factor discovered in recent years for enhancing the palatability of dry food for cats and, to a lesser degree, dogs.” (Lewis et al., 1987). In fact, digest is so effective that long-term exposure can result in apparent symptoms of addiction, necessitating considerable patience and persistence when implementing dietary changes.
Companion animal guardians are often also misled by insidious effects of digest. Although digest is usually autolysed chicken entrails, some batches are considered to taste more like beef, fish or turkey, etc., than other batches. It is the type of digest added, rather than the meat content, that determines the flavor designation on the label. Undifferentiated partially-dissolved ‘beefy’ tasting entrails might be labeled ‘Beef Stew,’ while the substitution of ‘fishy’ tasting digest may transform a can into ‘Ocean Whitefish.’
Opponents of vegetarian cat food on the basis that it is ‘unnatural’ usually display a curious inconsistency. They are generally happy to microchip, vaccinate, worm, sterilize, provide warmth, shelter and a regular food and water supply for their cats, all of which are unnatural. As Dick Gregory states in relation to dogs, “It never seems to occur to the pet owner that the dog would prefer to relieve itself on the carpet, and would probably prefer not to roll over and play dead! Pet owners think nothing of housebreaking a dog, or training it to do tricks or to attack unwanted visitors; in short, to do things for the owner’s benefit. But the same owner resists changing a pet’s diet for the pet’s benefit, and training the pet to eat it!” (Peden, 1999). The double standards displayed by otherwise caring animal guardians stem perhaps from a deep-seated personal need to justify the suffering and death involved in past and present dietary choices for themselves and their animals.
Regardless of whether or not a meat-based commercial diet is natural for cats, raising chickens, pigs, sheep or cows in intensive or extensive conditions of confinement, conducting surgical mutilations without anesthesia or analgesia during the normal course of husbandry, and then killing them at a young age in the frightening environment of a modern slaughterhouse, is hardly respectful of what is natural for them. These factors are unquestionably of far greater ethical weight than any discomfort a cat might or might not experience in transitioning to a vegetarian diet.
11. Health benefits of vegetarian diets
Numerous very happy guardians of vegetarian cats have reported their experiences in Peden’s (1999) Vegetarian Cats & Dogs. The health benefits of vegetarian diets appear to include decreased ectoparasites (fleas, ticks, lice and mites), improved coat condition, allergy control, weight control, decreased arthritis, diabetes regression, improved vitality and improved stool odor.
Ectoparasites and coat condition
Carol Arens of Arkansas reported that her cats appear to have less ectoparasites, after using an oat-soy recipe and Vegecat supplement. She states, “… the yeast in the recipe appears to repel fleas and ticks so that they are not a problem, in spite of the fact that we live in the country. Furthermore, Rudy appears to truly relish and anxiously anticipate the taste of her meals.” (Peden, 1999).
The Wall Street Journal reported the experiences of Mary Currier, of New Hampshire, who provides a sanctuary for 13 cats and three dogs. She stated, “Their fur is so much softer. It is so much shinier. I sound like a commercial, but I can’t believe it, I mean that’s how much better off they are. … If only you could just see these animals and feel the texture of their fur. I think you should put that in because it’s very important. Their fur doesn’t fall out like it used to. It’s thicker! It’s summer now, and the cats are in the house. It’s amazing. I can’t say enough about it and I tell everybody. I’m so grateful.” (Hwang, 1993).
Particularly touching is the story of Fletcher, recounted by Jennifer Friedman of Oregon: “[We found] Fletcher a year ago on a subway in New York City. He lived in a small crate that was caked with filth. Two homeless boys, barely able to care for themselves, fed him what they could from time to time. When Ben bought Fletcher off of them for 20 dollars, it did not look like he was going to make it. He was obviously severely dehydrated and malnourished. He had great difficulty walking; it seemed that the muscles in his legs had atrophied from living in the crate. His head was enormous for his small, bloated body and his fur was dry and matted. He was infested with fleas, mites, intestinal worms, and ringworm was spreading on various parts of his body. He also had severe behavioral problems, as would be expected, and had a tendency to attack rather viciously when something scared him. He was such a mess it was overwhelming, but I was afraid that a veterinarian would insist on putting him to sleep. So we decided to do our best on our own. Knowing where to begin was the most difficult part. We bathed him, cleaned out his ears, and used various herbs to treat the mites and ringworm (tea tree oil is excellent for getting rid of fungus) (*). We treated him very specially and with great care so as not to frighten him. We warned visitors not to pet him (we lived in a very tiny one bedroom and couldn’t really isolate him), but not many people wanted to visit us; everyone thought we were crazy! Only a few months earlier I had begun the transition to feeding my two other cats a vegetarian diet. So Fletcher was introduced to my cats’ favorite food at the time — ground chickpeas and brown rice mixed with veggies, oil, tamari, Vegecat, and tons of nutritional yeast. I also encouraged him to drink a lot; he especially loved soy milk (it’s still his favorite today), and to eat liquid vitamin E to help his skin heal. Needless to say, he was by far the easiest convert to a vegetarian diet (I’ve converted four other cats to date). He still eats his food with gusto and maintains a perfect body weight. Two months after we took Fletcher off the subway, we were moving to San Francisco. In order to take him on the plane, we had to get him a health certificate. We took him to a holistic veterinarian. Upon examining Fletcher, the vet commented on what a beautiful and healthy cat he was and what a wonderful disposition he had. I laughed as I told him the condition we found him in only two months earlier. The vet was incredulous.” (Peden, 1999).
(*) Tea tree (melaleuca) oil may cause
toxic signs when applied to, or licked from, the skin of cats and dogs,
particularly at inappropriate high doses, and is not recommended (Villar et
al. 1994).
Allergy control
Possibly assisted by the proliferation of artificial dyes, flavorings, preservatives (especially ethoxyquin), stabilizers and adulterated slaughterhouse products in commercial meat-based pet foods, the prevalence of companion animal allergies is rising. As stated by allergy expert and veterinarian Dr Alfred Plechner, animal products provoke the most allergic reactions, with beef at the top of the list for both cats and dogs. Changing to another commercial meat-based pet food usually does not resolve the problem, because of the similarity in ingredients used (Plechner & Zucker, 1986). Consequently several meatless Hills Canine Prescription Diets (k/d, dry u/d, dry d/d, and dry s/d) have been formulated to address allergies and degenerative medical conditions.
Itchiness is the most common sign of a food allergy for companion animals, although vomiting, coughing or wheezing (feline asthma) can also be present. Cats are more prone to food allergies than dogs, and become increasingly sensitive with age. They may develop skin disorders such as feline miliary dermatitis or eosinophilic granuloma complex.
Canadian Valerie Cline recounted her story of Barney: “I am proud to share my home with five cats, one of which is named Barney. Barney has suffered from allergies since I welcomed him into my home and these allergies are severe. I was told by many vets that he had food allergies, so I tried changing foods, but nothing I found, even the lamb and rice formulas, would work. Cortisone was the miracle “cure” presented to me every time I took him to the vet and without it his entire head would become red, swollen and itchy. Barney would scratch until all of his fur was gone and he drew blood. His ears would fill up with bloody scabs and his eyes would ooze bloody discharge until they became swollen shut and he would begin to wheeze. Barney was prescribed cortisone for two years until he became diabetic. All along I desperately asked many vets for an alternative, namely a diet I could prepare at home, but I was told that cortisone was a common treatment for feline allergies and that he was so severely ill that cortisone was the best route to take. Barney then required insulin injections every day. He went into insulin shock twice until the dosage was regulated. I was told that Barney would be diabetic and insulin dependent for the rest of his life. Only then was it recommended he start a “hypoallergenic diet” recommended by my vet. He was still allergic, but not severely. The food cost me $50 a month and he had to be kept separate from all the other cats because they ate different food and one mouthful of Science Diet and Barney would be in distress without the security of a cortisone injection for a quick fix. Then I found your product and within one month Barney was completely off the insulin and healthier than I had ever seen him. It has now been four months since he started eating Vegecat and he is no longer diabetic. His ears and eyes are clear and he looks fantastic!” (Peden, 1999).
Urogenital disease
Canadian Gwyn Watson describes the beneficial effects on ‘Layla’ of a vegetarian diet: “My cat Layla had a chronic bladder infection. She was on medication from the vet three to four times per year for the last four years. When she was not on medication I managed to keep it under some control with liquid vitamin C. Any stressful situation (i.e., moving) caused a flare-up. Since being on Vegecat she has not had any more trouble. I have not even been giving her the vitamin C. We make the Oat-Soy recipe and add chopped up carrots and sprouts. I found that I had hardly any trouble talking them into this new diet, also.” (Peden, 1999).
Weight control and arthritis
Obesity is an important and growing problem for domestic cats. Potentially serious health problems related to obesity include impaired cardiac function and respiratory disorders. As veterinarian Dr. Gregory MacEwen (1989) states, “Obesity can be one of the major conditions which can adversely affect the longevity of a pet.” Vegetarian diets contain decreased protein and fat levels and increased dietary fiber, all of which are effective in promoting a healthier weight.
Obesity also predisposes to arthritis. Veterinarian Dr. Michael Lemmon (1991) also holds free radicals accountable. He states, “Free radicals are formed during normal cellular metabolism, when cells take in nutrients, assimilate and utilize the nutrients, and then excrete the waste products. Some of these waste products are free radicals. Wherever you find poor quality foods being eaten, you will also find an excess of free radicals. Rancid fats and moldy grains are two leading sources of free radical production in animals. … Fat is an essential ingredient in any diet. Many commercial pet food manufacturers have problems with controlling the rancidity in fats added to the food they produce. They unsuccessfully use chemicals to try to curb this rancidity. American grain is quite often polluted with varying degrees of mold. Pet food manufacturers, for economic reasons, usually use the lower quality grain products in their pet food. Many cases of arthritis will respond effectively and quickly to antioxidant nutrients such as vitamin C, vitamin E, Beta-carotene, and selenium. Another highly effective antioxidant is the enzyme combination of superoxide dismutase (S.O.D.) and catalase.”
Diabetes regression
The excess body weight more commonly encountered on meat-based diets predisposes to obesity, and transitioning to a vegetarian diet can result in regression of diabetes. Alfredo Kuba of Mountain View, California, described an amazing regression of diabetes after transitioning his male rescued stray cat Mussi (castrated at 2 months of age) to a vegan diet (Kuba, 2004):
“I have been feeding my cats vegan food for over 14 years. I can tell you that my experience has been to say the least phenomenal. My cat Mussi who passed away last December was 17 years young. My wife and I rescued him only a couple of weeks old, abandoned. Before he became vegan, we used to feed him the ordinary, commercial "pet food" and he became ill with diabetes at just 3 years of age. I then decided to change his diet. I did some research and started him on Vegecat from Harbingers of a New Age. He loved the food even though it took patience to get him to gradually adjust to his new diet, about 5 to 6 months to be exact.
I noticed once he was eating 100% vegan his diabetes started to regress. Mussi was taking 14 units of insulin a day, 7 units twice a day to normalize his blood sugar before he was vegan. After the diet change to vegan, he rapidly reduced his intake need of insulin to only 2 units a day, and some days, and even weeks passed, when he didn't need the insulin.
Mussi's Diabetes was diagnosed by my vet and also the regression as well. I also checked his blood sugar once a week and when he showed symptoms of thirst and excessive urination. He started regressing when I started him on the vegan diet and it took about 6 to 8 months to get the insulin dosage from 14 units a day to only 2 units a day. Some times we noticed that he would go onto shock from too much insulin even at 2 units a day so we checked his blood and for weeks or months at a time he didn't require insulin, although he remained dependant on it once he got diabetes.
This was a dramatic improvement and quiet astonishing. We just rescued and adopted another stray cat we named him Tommy. We started him immediately with Evolution vegan food and we didn't have to get him to adjust to it, he loved the food from the get go!”
Improved vitality
Peden (1999) suggests the improved vitality seen in some cats after switching to a vegetarian diet may be due to conservation of energy previously used in the production and excretion of animal waste products, such as urea, creatinine, phenols, sulfates, and phosphates, which are much less encountered on a vegetarian diet.
New Zealander Ann Fullerton describes the effect on her Siamese, Melaney: “The good news is the excellent effect Vegecat had on Melaney, our beautiful Siamese. Mel is 10 years old, and was acting her age. But after just two or three weeks of Vegecat supplement, she was literally racing around and behaving as playfully as a kitten. It was wonderful to see her return to her old self. Ossie, our chinchilla, also benefited.…Did I ever tell you Melaney won two first prizes at the local cat show on her vegetarian diet? Alas, her prizes included a complimentary tin of horrible old Jellymeat! (Peden, 1999).
Stool odor
Peden (1999) recounts tales of improved stool odors of animals on vegetarian diets.
Kelp
Kelp is sometimes used in vegetarian animal diets, sourced from factories in the United States, Nova Scotia, Eire, Scotland, France, Denmark, the Netherlands, Norway, and South Africa. Ascophyllum nodosum is the species most commonly used. The meal derived from kelp is claimed to have a food value equal to that of oats, to prevent or cure mineral deficiency diseases, and to result in “better milk, eggs, meat, and fur” in ‘production’ animals (Thorvin, Inc., undated).
Kelp appears beneficial for bone strength. As stated by Zorn (1974) in Seaweed and Vitality, “Studies were made of the blood calcium, phosphorus, iron, and iodine on patients with fractures at different intervals during convalescence. Professor Cavanaugh learned that the healing time of fractures was reduced 20% by giving the patient a daily ration of kelp. Accordingly, it was clearly indicated in the study that kelp raised the level of calcium in the blood.”
The health hazards to cats and dogs (and, of course, to ‘food’ animals) that are inherent in commercial meat-based companion animal diets are extensive, and difficult to avoid (Knight, 2004). Additionally, growing numbers of informed consumers are unwilling to financially support the suffering and death inherent to the meat industry, and the environmental damage it causes (www.VeganOutreach.org provides extensive, thoroughly-referenced information on these issues). Consequently, growing numbers are exploring vegetarian alternatives.
Regardless of the combination of animal, plant, mineral or synthetically-based ingredients used, diets for cats, dogs, or other species should be formulated to meet the palatability, nutritional and bioavailability requirements of the species for which they are intended. Despite widespread prejudice against vegetarian pet food, even amongst (ill-informed) veterinarians and experienced animal carers, there is no scientific reason why a diet comprised only of plant, mineral and synthetically-based ingredients cannot be formulated to meet all of these needs. In fact, several commercially-available vegan (no animal product) diets claim to do so, and have jointly supported a healthy population of thousands of vegan cats, dogs and ferrets (who are also naturally carnivorous) for many years (Weisman, 2004). Regardless of the ingredients used however, sound quality control procedures, including regular laboratory nutritional analysis, should be implemented, to ensure products consistently meet these requirements.
Correct use of a complete and balanced nutritional supplement is essential to ensure the health of vegetarian companion animals, particularly cats. Regular urine pH monitoring is also important to detect and allow prevention of the urinary alkalinization, with its consequent potential for urinary stones, blockages and infections, that may result from a vegetarian diet in a small minority of cats.
· Baker DH, Czarnecki-Maulden GL. Comparative nutrition of dogs and cats. Annu Rev Nutr 1991;11:239-63.
· Belfield, Wendell O, Zucker, Martin. Very Health Cat Book. New York, NY, US: McGraw-Hill Book Company. 1983;153,198.
· Blood DC, Studdert VP. Bailliere’s Comprehensive Veterinary Dictionary. London: Bailliere Tindall. 1988.
· Burns et al. 1982. In National Research Council. Nutrient requirements of cats. Washington, DC: National Academy Press, 1986:12.
· DiBartola SP, Buffington CA, Chew DJ, McLoughlin MA, Sparks RA. Development of chronic renal disease in cats fed a commercial diet. J Am Vet Med Assoc. 1993 Mar 1;202(5):744-751.
· Frank G, Anderson W, Pazak H, et al. Use of a high-protein diet in the management of feline diabetes mellitus. Vet Ther 2001;2:238-246.
· Gillen J. Obligate Carnivore. Seattle, WA: Stein Hoist Books. 2003.
· Gray, Christina M.; Sellon, Rance K.; Freeman, Lisa M. Nutritional Adequacy of Two Vegan Diets for Cats. JAVMA 2004, 225(11):1670-1675.
· Hannah S. Role of dietary protein in weight management. Compend Contin Educ Pract Vet 1999;21:32-33.
· Hegsted et al. 1947. In National Research Council. Nutrient requirements of cats. Washington, DC: National Academy Press, 1986:12.
· Hill’s Pet Nutrition. http://www.hillspet.com/index.jsp, 21 Oct., 2003.
· Hwang, Suein L. The Wall Street Journal. 27 Oct. 1993:1.
· Jagger D. Date unknown. Vegepet Gazette. In Peden J. Vegetarian Cats & Dogs. 3rd Edn. Troy, MT, US: Harbingers of a New Age. 1999.
· James & McCay. 1950. In National Research Council. Nutrient requirements of cats. Washington, DC: National Academy Press, 1986:12.
· Kendall & Holme. 1982. In National Research Council. Nutrient requirements of cats. Washington, DC: National Academy Press, 1986:12.
· Kienzle E. Effects of carbohydrate on digestion in the cat. J Nutr 1994;124:2568S-2571S.
· Kienzle E, Engelhard R. A field study on the nutrition of vegetarian dogs and cats in Europe. Supplement to Compend Contin Educ Pract Vet 2001;23(9A):81.
· Kirk CA, Debraekeleer J, Armstrong PJ. Normal cats. In: Hand MS, Thatcher CD, Remillard RL, et al. Eds. Small animal clinical nutrition. 4th Edn. Philadelphia, PA, US: WB Saunders Co. 2000; 291-351.
· Knight A. Health hazards of commercial meat-based diets for cats and dogs. Unpublished. 2004. www.VegePets.info.
· Kuba, Alfredo. Personal communication to Andrew Knight re: regression of diabetes of his three year old male castrated cat ‘Mussi’ after transitioning from a commercial meat-based to a vegan diet. 17 Aug. 2004.
· Lewis LD, Morris ML, Hand MS Small Animal Clinical Nutrition. 3rd Edn. Topeka, KS, US: Mark Morris Associates, 1987.
· Lemmon, Michael. Arthritis Help. Sandpoint, ID, US: Harbingers of a New Age. 1991:3-5.
· MacDonald ML, Rogers QR, Morris JG. Nutrition of the domestic cat, a mammalian carnivore. Ann. Rev. Nutr. 1984;4:521-562.
· MacEwen, Gregory. Fat cats and dogs. Petfood Industry. 1989 Jul-Aug;31:28-34.
· Moore et al. 1980. In National Research Council. Nutrient requirements of cats. Washington, DC: National Academy Press, 1986:12.
· National Research Council. Nutrient requirements of cats. Washington, DC: National Academy Press, 1986.
· Papich, Mark. 5-minute consult drug formulary. In Tilley, Larry P & Smith, Francis W K. Eds. The 5-Minute Veterinary Consult: Canine and Feline. 3rd Edn. Philadelphia, US: Lippincott Williams & Wilkins. 2004. 1391-1456.
· Palackal T, Moretz R, Wisniewski H, Sturman J. Abnormal visual cortex development in the kitten associated with maternal dietary taurine deprivation. J Neurosci Res. 1986;15(2):223-239.
· Peden J. Vegetarian Cats & Dogs. 3rd Edn. Troy, MT, US: Harbingers of a New Age. 1999.
· Peden J. Personal communication to Andrew Knight re: feline vegetarian diets and Harbingers of a New Age vegan pet food. Feb 24, 2004.
· Pencovic & Morris. 1975. In National Research Council. Nutrient requirements of cats. Washington, DC: National Academy Press. 1986:6.
· Petrey, Stan. Absolutely NO-KILL: maintaining a vegan sanctuary. Animals’ Agenda 1998 Nov-Dec;18(6):30-31.
· Plechner, Alfred J. & Zucker, Martin. Pet Allergies. Inglewood, CA: Very Healthy Enterprises. 1986:20.
· Tennant, Bryn. Editor in chief. BSAVA Small Animal Formulary. 4th Edn. Gloucester, UK: British Small Animal Veterinary Association. 2003.
· Thorvin, Inc. Undated. Uses of kelp. http://www.thorvin.com/uses.htm#feed, 9 Aug. 2004.
· Villar D, Knight MJ, Hansen SR, Buck WB. Toxicity of melaleuca oil and related essential oils applied topically on dogs and cats. Vet Human Toxicol 1994; 36(2): 139-142.
· Westbeau, Georges. Little Tyke. Wheaton, IL, US: Theosophical Publishing House. 1986.
· Weisman E. Personal communication to Andrew Knight re: Evolution Diet vegan pet food. 24 Feb. 2004.
· Zoran D.L. The carnivore connection to nutrition in cats. J Am Vet Med Assoc 2002:1559-1567.
· Zorn, John W. Seaweed and vitality. Popular Library. 1974:85-86.
Appendix I: Nutritionally inadequate vegetarian diet produces malnutrition: A case study
After extensively searching the biomedical literature, I can confirm that one study does indeed exist demonstrating a disease of malnutrition, namely hypokalaemic polymyopathy, in cats fed a vegetarian diet. However, the diet was known prior to the commencement of the study to have been nutritionally inadequate. The study abstract is provided below.
I have been unable to locate any other studies demonstrating diseases of malnutrition in cats or dogs maintained on vegetarian diets. Despite the popular belief that vegetarian diets are inevitably harmful for companion animals, there were no studies demonstrating this using nutritionally complete and balanced vegetarian diets.
Leon A, Bain SA, Levick WR. Hypokalaemic episodic polymyopathy in cats fed a vegetarian diet. Aust Vet J. 1992 Oct;69(10):249-54.
John Curtin School of Medical Research, Australian National University, Canberra.
A previously undocumented hypokalaemic condition with a cyclical
nature, comprising acute bouts of polymyopathy followed by spontaneous
recoveries, is described in the cat. Cats being fed a high protein vegetarian
diet developed recurrent episodes of polymyopathy, characterised by
ventroflexion of the head and neck, stiff forelimb gait, lateral head-resting
and generalised muscle weakness. Plasma potassium concentrations (mean +/-
standard deviation) were reduced from 3.28 +/- 0.33 mmol/l at the beginning of
the experiment to 2.45 +/- 0.24 mmol/l during bouts of myopathy. This
hypokalaemia was associated with increased creatine kinase activities indicative
of muscle damage, and decreased urinary potassium concentrations, and was caused
by insufficient dietary potassium. Cats that received the same diet supplemented
with potassium did not develop hypokalaemic polymyopathy. Spontaneous recoveries
of affected cats were not associated consistently with increases in plasma
potassium concentrations. Plasma taurine concentrations decreased and glutamic
acid increased markedly in all cats fed the experimental diet. There was no
evidence of thiamin deficiency associated with the high glutamic acid intake.
Veterinarians should be aware that hypokalaemic cats, and in particular those on
potassium-deficient diets, may show cyclical disease with episodes of
polymyopathy recurring after periods of spontaneous clinical recovery. This
condition in cats may be a useful animal model for familial hypokalaemic
periodic paralysis in humans.
Appendix II: Inadequate quality control in feed production: A case study
See also associated Media Coverage.
A study by Gray et al. (2004) well illustrates the need for sound quality control procedures during manufacturing. Two commercially available vegetarian cat foods were subjected to blind (labels removed) nutritional analysis by Woodson-Tenent Laboratories. Diet A (Vegecat KibbleMix) was prepared according to company instructions using vegetable oil, flour, tomato paste, and the supplied powdered dietary supplement for adult cats. Diet B (Evolution canned diet for adult cats) required no additional preparation.
The laboratory results were compared to Association of American Feed Control Officials (AAFCO) nutrient profiles for the maintenance of adult cats. The Committee on Animal Nutrition, reporting to the Board of Agriculture within the National Research Council (NRC), has developed nutrient requirement standards for at least fifteen specific species of animals. AAFCO historically used the NRC recommendations, but in 1993 began publishing its own expanded nutrient requirements. These are now widely recognized as the required nutritional standards for animal feeds.
The results of Gray et al.’s study are listed in Table 1.
Table 1: Nutritional content of two vegan feline diets
Nutrient
Diet A
Diet B
AAFCO nutritional requirements
Protein
29.29 %
25.40 %
26 %
Crude Fat
9.17 %
15.33 %
9 %
Tryptophan
0.35 %
0.29 %
0.16 %
Methionine
0.47 %
0.33 %
0.62 %
Threonine
0.90 %
0.84 %
0.73 %
Valine
1.16 %
1.02 %
0.62 %
Isoleucine
1.03 %
0.91 %
0.52 %
Leucine
1.80 %
1.53 %
1.25 %
Phenylalanine
1.33 %
1.09 %
0.42 %
Lysine,total
0.71 %
1.20 %
0.83 %
Histidine
0.52 %
0.47 %
0.31 %
Arginine
0.95 %
1.49 %
1.04 %
Taurine
0.02 %
<0.04 %
0.10 %
Linoleic acid
1.55 %
3.72 %
0.50 %
Arachadonic acid
<0.01 %
<0.02 %
0.02 %
Calcium
0.80 %
0.06 %
0.60 %
Phosphorus
0.54 %
0.28 %
0.50 %
Selenium
7 ppm
0.48 ppm
0.1 ppm
Niacin
75.07 mg/kg
39.97 mg/kg
60 mg/kg
Retinol (Vit A)
618631 IU/kg
<1599 IU/kg
5000 IU/kg
Pyroxidine
3.28 mg/kg
2.91 mg/kg
4 mg/kg
Cobalamin
0.31 mg/kg
0.02 mg/kg
0.02 mg/kg
All values represent dry matter (DM) proportions.
While both brands claimed nutritional completeness on their labels, as Table 1 demonstrates, both were in fact deficient in select amino acid composition, trace minerals, vitamins, and arachidonic acid. Diet B was also deficient in overall protein content.
Protein
Diet B was just barely deficient at 25.4 %, while Diet A was adequate at 29.29 %. The AAFCO requirement was 26 %. The study authors suggest that the AAFCO level may be inadequate (Gray et al., 2004). While unable to substantiate this suggestion, they cited the protein levels of Hill’s Pet Nutrition diets for comparison: 33.5 % protein DM for a feline maintenance diet, and 28.3 % protein DM for cats with renal failure (Hill’s Pet Nutrition, 2003). High protein diets have been used or suggested to control signs of diabetes mellitus (Frank et al., 2001), inflammatory bowel disease (Zoran, 2002) and to reduce obesity (Hannah, 1999). On the other hand, the excessive protein levels found in some meat-based commercial brands predispose to chronic renal disease. DiBartola et al. (1993) demonstrated renal lesions in an alarming 56 % (5/9) of cats exclusively fed a meat-based commercial diet containing 40 % DM protein for two years.
Amino acids
Both brands were deficient in taurine; Diet A contained 0.02 % and Diet B contained less than 0.04 %. The AAFCO requirement was 0.10 %. Both brands were deficient in methionine; Diet A had 0.47 % and Diet B contained 0.33 %. The AAFCO requirement was 0.62 %. Lysine and arginine were deficient in Diet A at 0.71 % and 0.95 %, respectively. The AAFCO requirements were 0.83 % and 1.04 %.
Arachidonic acid
Arachidonic acid was deficient in both diets as well; Diet A contained less than 0.01 % and Diet B contained less than 0.02 %. The AAFCO requirement was 0.02 %. Diet A utilized a species of seaweed, Ascophyllum nodosum, as an arachidonic acid source. The deficiency detected could be due to variations in arachidonic acid concentration between batches of seaweed. Available light and nutrients during seaweed growth and age at harvest may all affect nutrient availability (Peden, 2004).
Vitamins
Diet B was deficient in several B vitamins as well. Niacin was inadequate at 39.97 mg/kg and cobalamin was marginal at 0.02 mg/kg. The AAFCO requirements were 60 mg/kg and 0.02 mg/kg respectively. Both were deficient in pyroxidine; Diet A contained 3.28 mg/kg and Diet B contained 2.91 mg/kg. The AAFCO requirement was 4 mg/kg. Diet B was also deficient in retinol (vitamin A) at less than 1599 IU/kg. The AAFCO requirement was 5000 IU/kg.
Minerals
Diet B was deficient in calcium (0.06%) and phosphorus (0.28%). The AAFCO requirements were 0.60% and 0.50% respectively. The Ca:P ratio was 0.21, as compared to an ideal of 1:1 to 2:1. A low ratio places cats at risk of nutritional secondary hyperparathyroidism and consequent loss of bone density. Interestingly, Diet A selenium levels of 7 ppm greatly exceeded the AAFCO requirement of 0.10 ppm. Selenium toxicosis has not been demonstrated in cats, although levels greater than 5 mg/kg are toxic to many other species (National Research Council, 1986).
Manufacturer response: Evolution Diet
In response to these results, Eric Weisman, Evolution Diet CEO (2004) stated, “We have ten to twenty thousand healthy and long living dogs, cats and ferrets living on the Evolution Diet. … Major animal sanctuaries use our products and stand behind them. These sanctuaries use our products because they have lower rates of illness and mortality when their animals are placed on our foods.”
Given that Gray et al.’s study illustrated that one tested Evolution Diet sample failed to meet the AAFCO nutrient profiles for maintenance of adult cats, one or more of the following possibilities must be true:
· The sample tested was nutritionally inadequate, but the great majority of samples sold and used are adequate. This may have resulted from a formulation error at the factory or from degradation over time of a very old sample. However, it is unlikely that a very old sample would have been retained for testing.
· The laboratory results were significantly in error for several nutrients tested. However, given a professional, accredited laboratory was used, and that the samples were tested blind to prevent bias, this seems very unlikely.
· The AAFCO cat food nutrient profiles for the maintenance of adult cats are highly conservative, and, although Evolution Diet pet food does not meet the AAFCO requirements, it does meet the actual the nutrient requirements for the maintenance of the great majority of adult cats. However, this also seems unlikely. Even if only 10% of cats required the nutrient levels specified by AAFCO, given that “ten to twenty thousand healthy and long living dogs, cats and ferrets [live] on the Evolution Diet” (Weisman, 2004), this would have resulted in a minimum of several hundred cats showing signs of nutritional deficiency following chronic feeding on the Evolution Diet. An affected population this large would most probably be detected, yet it has not been.
Hence the most likely possibility is that the sample tested was nutritionally inadequate, but the great majority of samples sold and used are adequate, and that a formulation error occurred at the factory.
Manufacturer response: Harbingers of a New Age
James Peden, of Harbingers of a New Age (2004), stated in relation to their Vegecat KibbleMix:
Overall
“We were frankly shocked by the analysis of the kibble made from Vegecat KibbleMix. I talked with our mixing personnel about the report and tried to understand how such a situation could have occurred. I’m convinced that this particular batch of Vegecat KibbleMix was made improperly, and have stressed to our personnel the importance of paying attention to the mixing process and if any errors are made to notify me immediately rather than pass on incorrectly mixed product.
…
We will reformulate our products in light of these unsettling facts, and submit to a lab for analysis
…
The fact that we’ve supported so many healthy vegan cats for so many years indicates that this particular batch was an isolated incident. But still, this is very alarming and requires our immediate attention.
…
Probably this was a one-time event, and never happened again.
…
It is so unfortunate that Tina [Tina Gray, study author] analyzed an atypical batch of KibbleMix. … It probably only affected 14 pounds total, since that is the small amount we make per batch by hand!
…
One more thing we plan on doing soon. We have a larger facility that we are moving into for mixing, and it will make it possible to keep our raw ingredients and premixes better isolated and organized.”
Protein
“One note about the protein. In our directions we state that any wheat flour can be used. We will change that to read only whole wheat or bread flour. That adds 1% protein over the results that Tina achieved, since Tina used all purpose flour.”
Taurine and selenium
“We don’t even add selenium to the kibble formulation. The taurine that we obtain is crystalline and assays at 98.5% purity.
…
[The mixing person] brought to my attention what must have happened. He mistakenly picked up the Vegecat Micro-Mix container instead of the Vegecat KibbleMix MACRO. That substitution would have resulted in grossly elevated selenium levels as well as a complete lack of taurine, since only the MACRO contains the taurine, and not the Vegecat Micro-Mix.
It’s a relief to me to know what happened, and why the values are so off. What
I’m going to do is put color coding on the containers that will match color
coding on the wall charts.”
Amino acids and vitamins
”We depend to a large extent upon a food yeast
for vitamins and amino acids. Apparently the nutrient profiles that we have for
that raw material are in error. What we plan to do is add additional methionine,
as well as add lysine, arginine, and pyroxidine (B6) to make up for the
deficiency. We will add a preformed source of arachadonic acid, instead of
depending upon the kelp to meet that requirement.
The excessive amounts of B12 and Vit A are alarming, and again I’ve stressed the
importance of paying attention to the mixing process.”
As with the Evolution Diet, the same three possibilities exist to account for both Gray et al.’s study results, and the large existing population of healthy cats maintained on Vegecat KibbleMix. Once again, the most likely possibility is that the sample tested was nutritionally inadequate, but the great majority of samples sold and used are adequate, and that a formulation error occurred at the factory. This hypothesis was confirmed and the error corrected by the company.
The steps described to rectify the nutritional inadequacies identified by Gray et al. are reassuring. As with Evolution Diet cat food, ultimate confirmation would be provided by repeatable independent laboratory analyses. By August 2004 no such confirmatory results were available.
Conclusions
Gray
et al.’s 2004 study illustrates the need for good quality control during
production to ensure that feed products consistently meet the nutritional
requirements specified by authorities such as AAFCO, and intended by their
manufacturers. It is entirely feasible that repeated independent laboratory
analyses of a range of commercial brands, both vegetarian and meat-based, would
similarly demonstrate nutritional inadequacies, and also inconsistency of
nutritional content over time.
Such findings in no way negate the ability of well formulated vegetarian or meat-based diets to meet all the nutritional requirements of the normal animals for which they are intended; they simply demonstrate the consequences of inadequate quality control, and the need for sound quality control systems during manufacture, including regular laboratory nutritional analyses.