by Armaiti May, D.V.M, C.V.A. • Dr. May’s Veterinary House Calls
For both ethical and health reasons, many vegetarians and vegans choose to feed their companion dogs vegetarian or vegan diets. Up to 50 % of commercial pet food brands are comprised of “meat meal” and “byproducts,” which include various body parts (such as beaks, brain, spinal cord tissue, bones, lungs, intestinal tracts) slaughterhouse wastes, 4-D meat (from dead, dying, diseased or disabled animals), supermarket rejects, as well as rendered dogs and cats from animal shelters. Other contaminants which have been found in commercial pet foods include old restaurant grease containing high concentrations of dangerous free radicals and trans fatty acids; PCBs, heavy metals and other toxins, particularly from fish; bacterial, protozoal, fungal, viral, and prion contaminants, along with their associated endotoxins and mycotoxins; hormone and antibiotic residues; and dangerous preservatives. Many speculate that the increase in incidences of cancers, kidney failure, and other degenerative diseases in our companion animals recently may be due to the harmful ingredients in many commercial meat-based pet foods. This has led people to feed alternative diets.
Dogs can be healthy and in fact, thrive on a vegetarian or vegan diet, as long as all necessary nutrient requirements are met. Dogs are biologically omnivorous, but can adapt well to a plant-based diet which meets all their nutritional needs. It’s important that the food be digested easily as well as have good palatability. The transition to a plant-based diet should be a gradual change (mixing the 2 foods in different proportions until the new food is given exclusively) to minimize the occurrence of gastrointestinal disturbances (such as diarrhea and sometimes vomiting).
In my clinical practice treating dogs, one of the most common ailments I diagnose and treat in dogs is skin allergies. Recurrent skin allergies (itching, scratching, biting, licking, leading to recurrent inflammation and infection of the skin) are usually due to one of the following (and sometimes a combination of these factors): (1) flea allergy dermatitis (the most commonly diagnosed); (2) food allergy (occurs in about 10-20% of cases); and (3) atopy, which is an allergy to something in the environment, such as house dust mites, pollen, grass, etc. Atopy is relatively uncommon. Most of the time a dog has a food allergy it is to a meat protein such as beef, chicken, or one of the other common meat sources. Vegetarian diets may bring these food allergic dogs relief from their skin allergies. A smaller percentage of dogs are allergic to soy, which may limit choices of commercially available vegetarian diets. In that case, if a caretaker wishes to feed a vegan diet, a homemade diet may be the next best option, but even more care must be taken to insure appropriate nutrient balance and supplements may need to be added to the diet.
Although dry kibble is generally better for dental health, if the dog is predisposed to urinary problems such as urinary crystals, canned (moist) food would be a better choice because the higher water intake helps to dilute out the urine and reduce the incidence of crystal and stone formation. One of the potential but unlikely risks associated with vegetarian diets in dogs is the occurrence of struvite crystals, which are more likely to occur if the urine pH becomes too alkaline. (This problem affects certain breeds of dog more commonly; the affected breeds include shih tzus, miniature schnauzers, bichon frises, miniature poodles, cocker spaniels, and Lhasa apsos.) Adding water to the dry food or encouraging the dog to drink water would be another way to address the issue of urine concentration which is related to crystal formation (the more dilute the urine, the less likely crystals are to form). To avoid any problems associated with urinary alkalinization secondary to the dog being on a vegetarian diet, I recommend that 2-3 weeks after switching the dog from a meat-based to a plant-based diet that he/she be brought to a veterinarian to have a urinalysis performed. This simple test will show what the urine pH is, as well as whether any crystals are present, therefore heading off any problems before they start. If the urine pH is too high (too alkaline) and/or struvite crystals are present, various acidifying agents can be used.
Although diet-related problems are unlikely to occur for dogs on a nutritionally complete and balanced diet, certain dog breeds are predisposed to DCM (dilated cardiomyopathy), a form of heart disease which may be influenced by lack of sufficient intake of taurine and/or carnitine (amino acids which are naturally occurring in flesh foods but can be added to the diet via synthetic supplements which are readily available. Doberman pinschers, boxers, “giant breeds” (Scottish deerhounds, Irish wolfhounds, Great Danes, Saint Bernards, Afghan hounds), and cocker spaniels are the dog breeds predisposed to DCM. The role of carnitine and taurine in the therapy of DCM remains controversial. American cocker spaniels with dilated cardiomyopathy generally respond favorably to taurine supplementation. Those not responding to taurine will often respond to the addition of L-carnitine. This http://www.carnitine-taurine.com/index.htm contains info on ordering supplements of taurine and carnitine for affected dogs. If someone has one of the predisposed breeds, it may be beneficial to supplement with taurine and/or carnitine if not already present in the vegetarian diet, in conjunction with consulting one’s veterinarian.