This book is intended to serve as a text book of Physiology for students of Veterinary colleges, schools, veterinary technicians, students seeking information about domestic animals. In all, the aim has been to present a clear and concise account of the functioning of various systems of domestic animals. Where appropriate, examples from human and non-domestic animals such as rat and rabbit have been cited. Physiology has now grown into a vast discipline. The book covers and explains the subject as per the latest syllabus being decided by the Veterinary Council of India for veterinary graduates. Finally, the book also elucidates a comprehensive yet a representative description of a large number of challenges faced by veterinary and animal science students.