Considering Vegetarian Diets
for Carnivorous Companion Animals
Lorelei A. Wakefield
Despite warnings from veterinarians, some animal caregivers are choosing to feed their pets vegetarian food for ethical reasons. Aside from nutritional health concerns, some veterinarians think it is inhumane to the animal not to feed a 'natural' diet. So why do these caregivers feel that vegetarian diets for their carnivorous companion animals are actually more humane? Most are vegans or vegetarians themselves who believe in animal rights and do not wish to contribute to the suffering of farm animals. They are considering the overall consequences of providing a flesh-based diet, not simply the consequences for their companion animals alone.
While this writing is not intended to serve as a justification for the animal rights philosophy or vegan lifestyle, an introduction to the theories contained therein will provide a background for the present argument. The moral equality theories posed by Peter Singer and Tom Regan provide the basis of the case for animal rights.
Peter Singer builds upon the utilitarian system of ethics created by Jeremy Bentham. The fundamental principles of utilitarianism are that (1): "The interests of every being affected by an action are to be taken into account and given the same weight as the like interests of any other being" and (2) choices should be made so to maximize pleasure and minimize suffering for the greatest number of affected beings. Beings are only afforded consideration when they have interests, meaning that they are sentient and thus possess the capacity for suffering and enjoyment. Utilitarianism encompasses egalitarianism. Singer poses that "No matter what the nature of the being, the principle of equality requires that its suffering be counted equally with the like suffering – in so far as rough comparisons can be made – of any other being." He also states that equality is a moral ideal, independent of "intelligence, moral capacity, physical strength, or similar matters of fact." The application here to animals is that their interests should be considered similarly to human interests when weighing the consequences of a decision. This is why many humans have chosen to avoid supporting the factory farm and slaughter industries by becoming vegetarian or vegan. More specifically to the case of vegetarian diets for companion animals, the interests (pleasures) of one's companion animal should be afforded equal weight to the interests (suffering) of farm animals. Since many farm animals must suffer and die to feed a single companion animal, though that single dog or cat receives gustatory pleasure and possible health benefits from the consumption of the farm animals, it follows that a vegetarian diet is the most ethical diet to feed to our companion animals. The application of utilitarianism to animal rights is perhaps best encapsulated in Bentham's famous quote: "The question is not, Can they reason? nor Can they talk? but Can they suffer?" 
Tom Regan proposes a rights view that assigns inherent value to individuals. This inherent value belongs to any subject of a life. Regan states that "all who have inherent value have it equally, whether they be human animals or not" and that "reason compels us to recognize the equal inherent value of these animals and, with this, their equal right to be treated with respect." Treating any animal without respect violates his or her individual rights. Regan's rights view is uncompromising. His position on commercial animal agriculture (as with any disrespectful use of animals) is abolitionist. That is, nothing other than the complete dissolution of the animal agriculture industry will satisfy the individual rights of animals that are currently routinely violated. 
The issue of feeding a vegetarian diet to carnivorous companion animals is highly controversial. Even vegans and animal rights activists diverge on the topic of feeding meat to companion animals. The essence of the argument against vegetarian food for dogs and cats is outlined below:
In his book Obligate Carnivore, Jed Gillen writes about the difficult decision caregivers are forced to make where essentially they are choosing between animals. He speaks of his newly adopted kitten: "Nature may have evolved her to be a carnivore, but it most certainly did not evolve me to go into the grocery store and buy dead animal parts to feed to her. Those same laws of nature that designed her to eat flesh did not tie my hands at all. If I chose to sustain this one life at the expense of many 'food animals,' on what would this decision be based? The fact that she was adorable and lived in my house, while they were just nameless and faceless statistics?" That sort of thinking is defined by Peter Singer as speciesism, which is arbitrary discrimination based on species.
From a utilitarian point of view, the reduced quantity of farm animal suffering and sacrificed lives far outweighs the possible health detriments and taste preferences of a single companion animal. Gillen explains further using Regan's principle of inherent value: "If I were killing chickens to feed a cat, what message would I be sending other than I value cats more than I value chickens, and it is perfectly valid to create a hierarchy of inherent worth based on species?" One could pose that caregivers feeding cats vegetarian food are forcing their morality on them. The counter to this argument is to ask if it is truly justifiable to force our immorality on countless other animals such that they will live and die in distress on factory farms.  It is important to recognize that animals do not have morals of their own – this is a human attribute. Does it cause any innate harm for humans to force beliefs on beings who lack a belief system to begin with (assuming of course that this will not cause them to suffer)?
Should these caregivers be forbidden from having pets? As a matter of fact, many vegetarians choose to avoid keeping companion animals so they can avoid this ethical dilemma. This is not an easy task though. Bryanna Clark Grogan points out that "because most of us love animals, when a stray presents itself at our door, we often find ourselves the reluctant (at first, anyway) caretakers of cats and/or dogs."  The alternative, of course, is that those animals would not have homes. More companion animals without homes essentially equates to more of them being euthanized in shelters. This is not an acceptable option.
Some dogs and especially cats may find vegetarian food unpalatable. Dogs exhibit the evolutionary advantage of marked flexibility in their catalog of acceptable food items based on availability and quality. Early experience dictates future food preferences in dogs. For instance, puppies raised on a mixed vegetarian diet for the first six months of their life will refuse to eat animal protein. The vast majority of dogs have more variety in their early diet, which leads them to be food neophilic (preference of novel flavors) later in life.  This helps ease the transition of older dogs onto a new vegetarian diet. Anecdotally, dogs adapt quickly and willingly to vegetarianism.  Cats, on the other hand, are notoriously finicky and will refuse to eat for days when offered food that they dislike. This behavior can lead to the development of hepatic lipidosis (fatty liver) if caregivers aren't quick to provide more appetizing food. Since the author is not aware of any first bite or volume consumed palatability tests on cat or dog vegetarian food, the suggestion that it is less palatable is mere speculation.
For the sake of argument, let's assume that vegetarian food is less palatable and denies companion animals the otherwise pleasurable experiences and gustatory satisfaction of meat consumption. Mylan Engel explains: "It would only be an impoverished life in a meaningful sense if there were no other pleasures comparable to the pleasures of eating meat and animal products that you could provide for your dogs [or cats]. With a little effort, you could provide your dogs with vegetarian foods that they would love."  Even if a vegetarian diet disagrees with a cat's taste preferences, it is unethical (and speciesist) to hold the taste preferences of one species above the grave misery and death of many animals belonging to other species. The companion animal will survive while the farm animals face imminent death. Another important consideration according to Gopi Sundaram is that "the 'rules' of domestication include getting fed what the master eats."  This historical perspective on the diet of our companion animals suggests that vegans who feed their pets vegan food are acting in a humane manner because diet sharing is an expected result of the human-domestic animal relationship.
Both dogs and cats belong to the order Carnivora due to certain anatomical similarities. Belonging to this order however does not implicitly mean an animal is a meat eater. Members of the order Carnivora such as bears and raccoons are omnivores, and the panda is primarily vegetarian.  Most veterinary nutritionists will agree that it is acceptable to feed dogs vegetarian food since they are nutritionally omnivores and with a little effort can thrive on a vegetarian diet. In fact, at least one dog food, Nature's Recipe¨ Vegetarian Canine Formula, has proven through feeding trials that it provides complete and balanced nutrition for adult maintenance according to AAFCO (Association of American Feed Control Officials).  As a result, the majority of vegans and animal rights activists feel that it is fine (if not preferable) to feed canine companions a vegetarian diet. Cats however are obligate carnivores, meaning that flesh is considered an essential part of their diet.
Most veterinarians strongly recommend against feeding cats a vegetarian diet. While vegetarian cat food can be supplemented and formulated to meet AAFCO standards, there is a paucity of scientific data regarding bioavailability of essential nutrients and long-term health effects. The bioavailability of synthetic taurine in these foods, for example, is unknown. However, the majority of commercial cat foods add synthetic taurine because the natural taurine is denatured during high-heat processing. So there is a huge sample of cats lacking any signs of deficiency during a lifetime of consuming and utilizing synthetic taurine. Still, the bioavailability of many supplemented nutrients remains unknown.
Anecdotally, the thousands or tens of thousands of cats currently on vegetarian diets are in adequate to excellent health.3 Veterinarians such as Beth Johnson, DVM, have remarked on the apparent health of these animals, "The Home at Last [absolutely no-kill vegan sanctuary] 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."6 To date, there have been no scientific studies demonstrating nutritional adequacy of fully supplemented vegan cat food in vivo. Part of the problem is that those who would feed vegan cat food are generally against animal testing, including food trials with cats in cages. So, study design is a limiting factor in itself. Recently, the two commercially available US vegan cat foods were evaluated and both were shown to be nutritionally inadequate.  Unfortunately, the investigators were only able to evaluate one sample of each brand, which leaves a lot of room for sampling error, lab error, and variation in batches or quality control issues. Should those foods be truly lacking in several essential nutrients, we still don't know that this would be detrimental to feline health without examining the cats eating those foods. One paper and a single case report found deficiencies in vegetarian cats, but none of those cats were on the fully supplemented commercial diets available today, so those findings are essentially irrelevant.  ,  Even if we assume the worst, that vegan cats may be slightly less healthy or have slightly shorter life-spans compared to their meat-consuming counterparts, that does not justify the suffering and slaughter of numerous farm animals.
Conventional flesh-based cat food presents its own dangers. Pet foods often contain by-products of the human food industry. This includes U.S. Department of Agriculture grade 4-D meat, which stands for dead, dying, disabled and diseased. This meat contains cancerous material from the reject pile of slaughterhouses.  Also included are farm animal heads, intestines, hooves and ligaments.  Brain material in the heads can contain prions, the infectious organisms that cause diseases such as Mad Cow Disease (Bovine Spongiform Encephalopathy, or BSE) and Chronic Wasting Disease. While dogs appear resistant, cats are susceptible to BSE. Approximately 90 cases of BSE in domestic cats have been reported in the UK.  There have even been instances where euthanized cats and dogs (complete with sodium pentobarbital euthanasia solution) have ended up in the US and Canadian pet food supply.  Vegetarian pet foods at least avoid the use of all these hazardous ingredients.
The fact that pet food contains by-products of the meat industry intended for humans cannot justify its purchase. By buying these pet foods, caregivers are financially supporting the meat industry that slaughters farm animals. Also, high quality pet foods often recommended by veterinarians do not contain by-products at all. In such cases, animals are slaughtered for the specific purpose of being incorporated into cat and dog food.
A major source of contention in the debate over vegetarian food for companion animals is that it is not a natural diet for them. As previously described, dogs are omnivorous just as humans are, so a vegetarian diet is not wholly unnatural for them. Cats though, are obligate carnivores. So, let us examine the conventional cat food diet. Would you ever come across a cat hunting a cow, pig or turkey in nature? How about a cat suckling milk off a cow's teat? Cats certainly are not fishers by nature. The true natural feline diet consists primarily of live rodents, birds and insects – little of which you will find in any conventional meat-based cat food. Caregivers could theoretically let their cats outside to procure a proper diet for themselves, but even this opposes the natural order of the ecosystem. European settlers artificially incorporated cats into the North American bionetwork a few hundred years ago. Thus small mammals and birds are forced to contend with an unnatural predator. As a result, outdoor and feral cats cause a great number of species endangerment and extinction.3
The entire domesticated animal situation can be considered unnatural. These companion animals are fed food out of a bag or can by humans rather than hunting or otherwise procuring it themselves. Besides, the characteristic of being natural in no way implies being moral or ethical. Gillen points out that "our whole animal rights movement is not based on what is natural but on what is ethical; what should be rather than what has historically been."3
Though no official vegan position exists on the subject of vegetarian cat diets, some animal rights organizations have taken sides on the issue. For instance, People for the Ethical Treatment of Animals advocate feeding dogs and cats vegetarian diets and provide educational information on their website. As more light is shed on this subject and as more veterinarians consider the possibility that pets can be healthy on vegetarian diets, chances are that more vegetarian caregivers will make the ethical choice to feed vegetarian food to their dogs and cats. In doing so, they will theoretically reduce the amount of suffering and slaughter of millions of farm animals. When caregivers feed their pets vegetarian food, they do so with good reason.
 Peter Singer. "All Animals are Equal" in Animal Rights and Human Obligations, 2nd edition, eds. Regan and Singer (Englewood Cliffs, NJ: Prentice Hall, 1989), pp. 73-86.
Tom Regan. The Case for Animal Rights
(Berkeley and Los Angeles: University of California Press, 1983) pp. 13-26.
Tom Regan. The Case for Animal Rights (Berkeley and Los Angeles: University of California Press, 1983) pp. 13-26.
 Jed Gillen. Obligate Carnivore. Seattle, WA: SteinHoist Books, 2003.
 Bryanna Clark Grogan. "Vegetarian Cats and Dogs" from Soybean Diaries, 1996. Reprinted by EarthSave Canada.
 Chris Thorne, "Feeding Behaviour of Domestic Dogs and the Role of Experience," in James Serpell (ed.), The Domestic Dog: Its Evolution, Behavior, and Interactions with people (Cambridge University Press, 1995), p 103-113.
 Stan Petrey. "Absolutely No-Kill: Maintaining a vegan sanctuary." The Animal's Agenda, 1999. Baltimore, MD.
 Mylan Engel. Letter in response to Confusions and Fallacies About Animals, Part 19 by Keith Burgess-Jackson, 2004. http://animalethics.blogspot.com/2004_11_01_animalethics_archive.html
 Gopi Sundaram. Letter in response to Confusions and Fallacies About Animals, Part 19 by Keith Burgess-Jackson, 2004. http://animalethics.blogspot.com/2004_11_01_animalethics_archive.html
 Myers, P. 2000. "Carnivora" (On-line), Animal Diversity Web. Accessed April 29, 2005 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carnivora.html
 Nature's Recipe¨ Vegetarian Canine Formula, Del Monte Foods.
 Gray, Christina M.; Sellon, Rance K.; Freeman, Lisa M. Nutritional Adequacy of Two Vegan Diets for Cats. JAVMA 2004, 225(11):1670-1675.
 Kienzle E, Engelhard R. A field study on the nutrition of vegetarian dogs and cats in Europe (abstr.). Compend Contin Educ Pract Vet Suppl 2001;23:81.
 Leon A, Bain SA, Levick WR. Hypokalemic episodic polymyopathy in cats fed a vegetarian diet. Australian Veterinary Journal. 69(10):249-54, 1992 Oct.
 Peden J. Vegetarian Cats & Dogs. 3rd Edn. Troy, MT, US: Harbingers of a New Age. 1999.
 Weisman, E. "The Actual Ingredients Meat Based Pet Food Companies Use in Dry and Canned Foods." 2002. Saint Paul, Minn.
 Linda Bren. Agencies Work to Corral Mad Cow Disease. FDA Consumer Magazine, May-June 2004 issue.
 Ann N. Martin. Food Pets Die For. Troutdale, OR NewSage Press, 1997.
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