Abstract
This chapter explores the use of drugs for veterinary mental health care and behavior modification. It focuses on neuropeptides. Neuropeptides have major roles in regulating the activity of neuronal signaling between brain regions, and expression of neuropeptides and their receptors has served as an important genetic substrate on which evolutionary forces have optimized behaviors. The chapter presents a summary of the receptor selectivities and efficacies of opioid drugs. The neurohypophyseal hormone oxytocin (OT) regulates biological functions in both peripheral tissues and the central nervous system. OT is a critical mediator for two of the fundamental defining reproductive characteristics in mammals, namely, placental birth and lactation. The G protein-coupled receptor can be linked to different G proteins leading to different functional effects. It has accordingly been proposed that OT may be evolutionarily linked to social coping strategies.