For a "solid text" covering the intersection of animal behavior and veterinary science, the following resources are widely considered foundational for students and practitioners. Core Textbooks
Veterinary science dictates that Bloodwork, urinalysis, and imaging must precede a referral to a trainer.
: Behavior is often the first indicator of physical illness. A cat that stops jumping onto counters may not just be "lazy"; it may be suffering from osteoarthritis. A dog that suddenly becomes aggressive might be reacting to chronic pain.