Q For ethical reasons, I am a vegetarian. I am the owner of a cat and two dogs. I feel very guilty feeding them animal products, but I continue to do so for their health. Can I safely make vegetarians out of them.

A; The first time I (Henri Bianucci) gave this matter any thought was during my residency. One afternoon, while conducting a teaching lab, I heard a student mention that she was a vegetarian. I knew this student, and knew that she had cats.

I asked, “Are you a vegetarian for health reasons, or is it out of concern for animal welfare?”

“Animal welfare,” she exclaimed.

“Well, what do you feed your cats?” I asked.

Her response surprised me. She broke into tears and upbraided me for putting her in an uncomfortable position in front of her classmates.

I truly asked only because I was interested in how she handled this dilemma. Clearly this was something she had not quite come to terms with. It was a clash between her moral convictions, and the bare necessities of her cats’ nutrition.

She is not alone. As I mentioned in a recent column, there is a growing awareness in this country that the conditions food animals are subjected to are manifestly cruel. When we consume animal products, we become participants in this. That has driven many to become vegans and vegetarians, and they have extended this practice to their pets’ diets as well. Many more are interested in doing so, but can’t quite make the leap, often due to the belief that dogs and cats are, naturally, pure carnivores.

For cats, this belief is fairly accurate. For example, cats require an amino acid called taurine because their body cannot synthesize (make) it. They can only obtain this from meat sources or supplements. Vitamin B-12, cobalamin, is another nutrient that cats best obtain from meat. Without these vital nutrients cats will develop heart failure, blindness, neurological disease and anemia.

Convincing studies that cats can reliably derive these nutrients from plant-based diets are lacking. For this reason, I could only advise that a vegetarian program for cats be implemented under the supervision and monitoring of a qualified veterinarian or veterinary nutritionist.

Dogs are much better candidates for conversion to a plant-based diet. Dogs belong to the order carnivora. They descended from the wolf 15,000 to 20,000 years ago. So, they are primarily carnivores, but through their association with man, their gastrointestinal tracts have evolved in the direction of the omnivore, and they actually can derive virtually all of their nutritional requirements through a vegetarian diet and supplements.

A 2006 National Research Council report by a team of leading experts in animal nutrition definitively confirmed that a vegetarian diet for dogs is completely healthy as long as it provides adequate protein and vitamin D.

Warren, a black Labrador, was plagued with skin and digestive problems. At the age of 1, he was diagnosed with a high-grade cancer and was given no more than a year to live. His owner knew he had to act. After painstaking research, he came to the conclusion that if his diet wasn’t killing Warren, it certainly wasn’t helping.

He concluded that, aside from ethical concerns about using animals for food, “Commercial dog food is essentially slaughterhouse waste products. It’s disgusting.”

He formulated his own vegetarian diet, primarily made up of lentils, basmati rice, and fresh vegetables. Warren’s skin and intestinal problems resolved almost immediately after implementing the new diet.

Warren, now four years out from a terminal cancer diagnosis, came to me for the removal of a suspicious mass on his spleen. Before I even knew he was a vegetarian, I was immediately struck by his appearance. He was solid, sharp and had a thick, lustrous, black coat. He appeared exceptionally vital, and demonstrated a vertical leap that Michael Jordan would envy.

He underwent surgery to remove his spleen. After four tense days, the diagnosis returned: It was a benign hematoma, essentially a pocket of blood. A huge relief to his owner and a reason to continue to believe in his dietary choice.

It is a widely held sentiment that its just not natural to deprive a dog of meat. It is an understandable belief until one really considers what is allowed into a bag of some dog foods. For example, meat is derived from what is known as “The four D’s,” meaning animals arrive at the slaughterhouse dead, diseased, dying or disabled. In most states, it is legal to use what are otherwise unusable animal parts in pet food. Furthermore, these diets already contain large amounts of plant-based starches from corn and other grains. There is really nothing “natural” about what most dogs consume in commercial foods.

There are commercial vegetarian dog foods, which are nutritionally complete. When selecting these, it is recommended that you select a food that conforms to the standards set by the Association of American Feed Control Officials (AAFCO). Alternatively, you may opt for cooking your own recipe up at home. If so, it is recommended that you consult a credentialed animal nutritionist, or follow a diet that was created by one, to ensure that its nutrients are properly balanced.

If you are not quite ready to make the full plunge into vegetarianism, you could supplement a conventional commercial diet with plant-based meals.

Dr. Henri Bianucci and Dr. Perry Jameson are with Veterinary Specialty Care LLC. Send questions to petdocs@postandcourier.com.