This textbook explores the fundamental qualitative and quantitative aspects of veterinary physiology. It presents the morphological description of the organs, tissues, and cells involved in the physiological system with species variation. The book provide the most up-to-date information and in depth knowledge in animal physiology. The book addresses a broad range of topics, including the physiology of digestion in, monogastric animals, ruminants, and birds, and cardio vascular and respiratory system in different animals. The chapters contain a wealth of information on the areas related to the endocrine system, excretory system, body fluid homeostasis, hematology, male and female reproductive systems, coordination of body functions, and regulation of brain functions and sense organs. Further, this book acquaints students with advanced topics like immune system, assisted reproductive technology, ovarian dynamics, environmental physiology and thermoregulation, and behavioral physiology.