Dogs, our sunny, selfless shadows, crave little more than a daily walk, a treat or two, and their human’s happiness. But increasingly, their own happiness is the topic of concern in veterinarian offices, dog parks, and internet forums. Prozac prescriptions for dogs are on the rise, veterinarians across the country acknowledge, along with a myriad of cheaper generic mood stabilizers sold for humans but applied to pets’ separation anxiety, socialization fears, biting habits, or other problematic behavior. That increase, experts told STAT, says more about the human mental health crisis in America — and the ready availability of inexpensive generic...