This issue of Veterinary Clinics of North America: Small Animal Practice, edited by Bruce W. Christensen, focuses on Small Animal Theriogenology, with topics including: Assisted Reproduction in Male and Female Cats; Population Control in Small Animals; Practitioners considering SA Therio; Evaluation of Canine Sperm and Diagnosis of Semen Disorders; BSE in the Canine Female; Artificial Insemination in Dogs; Estrus Manipulation in Dogs; Endocrine testing in Small Animals; Endocrine Disruptors; Mismating Diagnosis and Protocols; Gestational Aging and Assistant Parturition Date Determination; Small Animal Pyometra; Periparturient Diseases in the Dam; Small Animal Neonatal Health; Herpesvirus; Prostate Disease; and the Future of Biotechnology.