Interesting discussion. However, as pointed out by this very site, actual scientific evidence, vs anecdotal evidence, points to the fact that the entire Canidae and Felidae families are both physically and biologically carnivorous.
/canine-nutrition/dogs-carnivores-omnivores/
https://www.waltham.com/dyn/_assets/_pdfs/winss/WINSS2010Proceedings.pdf
https://www.nap.edu/read/10668/chapter/1
People like to pick and choose supportive statements from the famous Knight and Leitsberger study “Vegetarian versus Meat-Based Diets for Companion Animals” which supports their claims for the undisputed nutritional value of vegan living for dogs and cats. Unfortunately the study itself does not validate those claims and even questions the results of the “famous” PETA study in 1994 with “The precise diets used, and their level of nutritional adequacy, are unknown.” They also state of the studies they reviewed (including PETA) “The standard of evidence offered by these studies and case reports varies significantly, and very few, if any, meet the standards of well-designed RCTs that are considered the cornerstone of Evidence-Based Medicine.” While Knight and Leitsberger concur that a significant and growing body of population studies and cases suggest that cats and dogs may be successfully maintained on nutritionally sound vegetarian diets long-term, and indeed, may thrive, they also state, “cats and dogs maintained on these diets also experience health problems, and occasionally die.”
It’s a very well done study, but it does challenge the claims and assertions of both camps, and calls for more research to be done. http://www.mdpi.com/2076-2615/6/9/57/htm
The fact remains that while some dogs and cats may “thrive on vegan diets”; their physical biology is that of their carnivore families. Their “tearing” back teeth, shorter intestinal lengths, higher stomach acid levels and faster digestion, and lack of production of the enzyme amylase in their salivary glands all clearly and uniquely identify them as being biologically carnivores. They simply do not have the “grinding” molars of herbivores or omnivores. They do not have the slower digestive tracts and associated longer intestines that both herbivores and omnivores have. In addition, they do not produce amylase in their salivary glands, a hallmark difference between carnivores and herbivore/omnivores. Dogs and cats may have “adapted” to living with us, but they are certainly biologically and physically carnivores like their relatives. Any diet, vegan or classical, has to meet the needs of their carnivorous biology.
