Knight A. The author responds. J. Amer. Vet. Medical. Assoc. 1 Apr. 2005; Vol. 226 No. 7 pp. 1047-1048.

 

[The following ended a debate sparked by Gray CM, Sellon RK & Freeman LM: Nutritional Adequacy of Two Vegan Diets for Cats. J Amer Vet Med Assoc 2004, 225(11):1670-1675 (see www.vegepets.info, Vegetarian Feline Diets, Appendix II), in which two commercially-available vegan cat foods were found to be deficient in a range of essential nutrients. J. Amer. Vet. Med. Assoc. is the world’s leading veterinary journal.]

 

I thank Dr. Fox for raising the important concept of faith during his discussion of vegetarian cat and dog diets. To the believer, faith provides the justification for a belief held in defiance of logical reasoning or evidence to the contrary. Exactly such a belief is held by those opposed to nutritionally sound vegetarian companion animal diets without first critically reviewing the evidence.

 

I recently spent several months examining that evidence. After extensively searching the biomedical literature, I can confirm that one study (1) does report development of malnutrition, namely hypokalemic 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 predictability of the outcome in such a case raises questions about whether the study might have been conducted for political reasons, rather than to answer genuine scientific questions about the viability of vegetarian diets.

 

Despite the belief of many veterinarians that vegetarian diets are inevitably harmful for companion animals, there were no studies demonstrating this popular “fact,” using nutritionally complete and balanced vegetarian diets. Interestingly, though, numerous studies do exist demonstrating increased risks of degenerative diseases such as kidney failure (2); liver, musculoskeletal, and neurologic diseases (3); birth defects (4); and bleeding disorders (5), following chronic maintenance on commercial meat-based diets.

 

Until studies examining the long-term health status of cats and dogs fed nutritionally sound vegetarian diets are published, our evidence will remain limited to case reports. Fortunately, a large number of these are described on Web sites and in books. (6) They commonly illustrate substantial benefits for dogs and cats after transitioning to a vegetarian diet, including decreased ectoparasites and food allergy reactions, improved coat condition, obesity reduction, regression in signs of arthritis, diabetes, cataracts, and urogenital disease, and improved vitality. I have observed some of these effects in my vegetarian feline patients, and enjoy receiving glowing accounts from their owners.

 

To be fair, there are also accounts of animals that have been harmed by nutritionally inadequate vegetarian (and meat-based) diets. However, these are of little scientific relevance to an examination of the viability of nutritionally sound vegetarian diets. All they establish is the necessity of education about the importance of using a complete and balanced vegetarian diet or nutritional supplement.

 

Regular urine pH monitoring is also important to detect and allow prevention of the urinary alkalinization that may occur in a small percentage of vegetarian cats, with consequent increased risks of urinary calculi, blockages, and infections.

 

Whether we like it or not, ever increasing numbers of clients concerned about vegetarianism, health, and ethics are going to attempt to maintain their cats and dogs on vegetarian diets. It is our responsibility as scientists, veterinarians, and animal welfare advocates to put aside any faith-based opposition to vegetarian diets for companion animals we may have had and instead learn about them so that we may best assist our clients to maintain the health and well-being of their pets.

 

Andrew Knight, BVMS

Director, Animal Consultants International

 

1. Leon A, Bain SA, Levick WR. Hypokalaemic episodic polymyopathy in cats fed a vegetarian diet. Aust Vet J. 1992;69:249-254.  

2. DiBartola SP, Buffington CA, Chew DJ, et al. Development of chronic renal disease in cats fed a commercial diet. J Am Vet Med Assoc. 1993;202:744-751.  

3. Dow SW, Fettman MJ, Curtis CR, et al. Hypokalemia in cats: 186 cases (1984-1987). J Am Vet Med Assoc. 1989;194:1604-1608.  

4. Freytag TL, Liu SM, Rogers QR, et al. Teratogenic effects of chronic ingestion of high levels of vitamin A in cats. J Anim Physiol Anim Nutr (Berl). 2003;87:42-51.  

5. Strieker MJ, Morris JG, Feldman BF, et al. Vitamin K deficiency in cats fed commercial fish-based diets. J Small Anim Pract. 1996;37:322-326.  

6. Peden J. Vegetarian Cats & Dogs. 3rd Ed. Troy, Mont: Harbingers of a New Age. 1999.

 

Veterinarian Andrew Knight BSc., BVMS, CertAW, MRCVS, is the Founder, Director and web designer of Animal Consultants International. He is an expert on humane alternatives to harmful animal use in education, animal experimentation, and vegetarian companion animal diets. An active animal advocate since 1995, he has extensive public speaking, media, research and writing experience.