One argument could state that veterinarians study multiple fields of the health and disease of mammals, amphibians, birds, reptiles, and fish whereas physicians only study the human body, therefore making it unnecessary for physicians and veterinarians to collaborate since the variation is far too large between a human and the long list of organisms a veterinarian has to study. Variation in brain activity results in a variety of treatments. Another argument regarding location would state. Animals living in the jungle versus a domesticated pet will have variations that ultimately affect the similarities between animals and humans. Although humans are animals, the differences outweigh the similarities between a human and, let's say a frog or even a lion. The location of the animal will affect nearly everything about their brain activity, different diseases they may be exposed to, treatments that are available, etc. Don't get me wrong, I think physicians can learn a lot from veterinarians, but this was for an assignment, so I had to come up with something. This is the best I got. Feel free to tweak it though, I'm sure there are other reasons as to why they don't need to collaborate.
