A veterinarian (from Latin veterinae, "draught animals") is an animal doctor, a practitioner of veterinary medicine. Although veterinarians hold doctoral degrees in veterinary medicine, not all veterinarians enter clinical practice. Those that work in clinical settings practice medicine in specific fields, such as companion animal or "pet" medicine, reptile medicine, ratite medicine, livestock medicine, equine medicine (e.g. sports, race track, show, rodeo), or laboratory animal medicine. Other veterinarians research areas of human medicine, veterinary medicine, and pharmacology. Research veterinarians were the first to isolate oncoviruses, Salmonella species, Brucella species, and various other pathogenic agents. They also helped conquer malaria and yellow fever; solved the mystery of botulism; produced an anticoagulant used to treat human heart disease; and developed surgical techniques for humans, such as hip-joint replacement, and limb and organ transplants.

Like all physicians, veterinarians must make serious ethical decisions about their patients' care. There is ongoing debate over the ethics of performing certain controversial procedures, like declawing cats and docking tails, cropping ears, and debarking dogs. In some countries, these procedures are illegal, and therefore their practice is contentious. The Veterinarian's Oath was adopted by the American Veterinary Medical Association's House of Delegates July 1969, and amended by the AVMA Executive Board, November 1999. It goes as follows:
"Being admitted to the profession of veterinary medicine, I solemnly swear to use my scientific knowledge and skills for the benefit of society through the protection of animal health, the relief of animal suffering, the conservation of animal resources, the promotion of public health, and the advancement of medical knowledge.
I will practice my profession conscientiously, with dignity, and in keeping with the principles of veterinary medical ethics.

Some veterinarians work in a field called regulatory medicine ensuring the nation's food safety by working with the USDA FSIS, or work by protecting us from imported exotic animal diseases by working for the USDA APHIS. The emerging field of conservation medicine involves veterinarians even more directly with human health care, providing a multidisciplinary approach to medical research that also involves environmental scientists.

More than 3,800 veterinarians in the USA currently work at veterinary schools where they teach student vets what they need to know to graduate teaching is another career path for a veterinarian.
Veterinary school is a tertiary educational institution, or part of such an institution, which is involved in the education of future veterinary practitioners (veterinarians). The entry criteria, structure, teaching methodology and nature of veterinary programs offered at veterinary schools vary considerably around the world. In the U.S., a doctorate of veterinary medicine degree (D.V.M.) (Or in the Veterinary Medical School at the University of Pennsylvania, a degree of veterinary medical doctor (V.M.D.) is awarded) is a four-year program. The program generally consists of 21?2 to 3 years of mostly traditional classroom coursework followed by the clinical rotations. Currently, unlike human medical school, a subsequent internship and/or residency are not required, but are optional to those who choose to seek further education and possible accreditation. Unsurprisingly, the number of veterinarians pursuing internships and/or residencies will continue to increase as the understanding of veterinary medicine continues to grow greater. A good veterinarian enjoys working with animals and their owners. Admission into veterinary medical school is so competitive that in the United States it is far easier to gain acceptance into either a medical school or a top Law School than to meet the GPA requirements for most veterinary schools. This situation occurs mostly because there are far fewer schools, allowing the schools to be much more selective. According to the US Department of Labor, only 1 in 3 applicants were accepted into a veterinary program in 2002. Prerequisites for admission include the undergraduate studies listed under veterinary medicine and extensive veterinary experience (typically about 500 or more hours) in private practice or other veterinary environment. The average veterinary medical student has an undergraduate GPA of 3.5 and a GRE score of approximately 1800. US graduates are awarded either a Doctor of Veterinary Medicine (DVM) or the less common Veterinary Medical Doctor (VMD) degree, depending upon the traditions of the veterinary school.

Public health medicine is another option for veterinarians. Veterinarians in government and private laboratories provide diagnostic and testing services. Some veterinarians serve as state epidemiologists, directors of environmental health, and directors of state or city public health departments. Veterinarians are also employed by the US Agriculture Research Service, Fish and Wildlife Service, Environmental Protection Agency, National Library of Medicine, and National Institutes of Health. The military also employs veterinarians in a number of capacities caring for pets on military bases, caring for military working animals, and controlling various arthropod-borne diseases or other such things.

Veterinary medicine is the application of medical, diagnostic, and therapeutic principles to companion, domestic, exotic, wildlife, and production animals. Veterinary Science is concerned with the scientific basis of animal production, health and disease. It requires the acquisition and application of scientific knowledge in several disciplines and uses technical skills towards the solution of animal production, health, management and welfare problems.
Veterinary medicine is informally as old as the human/animal bond but in recent years has expanded exponentially because of the availability of advanced diagnostic and therapeutic techniques for most species. Animals nowadays often receive advanced medical, dental, and surgical care including insulin injections, root canals, hip replacements, cataract extractions, and pacemakers.

Veterinarians assist in ensuring the quality, quantity, and security of food supplies by working to maintain the health of livestock and inspecting the meat itself. Veterinary scientists are very important in chemical, biological, and pharmacological research.

In many countries, equine veterinary medicine is also a specialized field. Clinical work with horses involves mainly locomotor and orthopaedic problems, digestive tract conditions (including equine colic, which is a major cause of death among domesticated horses), and respiratory tract infections and disorders.

As in the human medical field, veterinary medicine (in practice) requires a diverse group of individuals to meet the need of patients. In addition to veterinarians, many veterinary hospitals utilize a team of veterinary nurses and veterinary assistants to completely care for healing, critical and well animals. Veterinary nurses are generally registered as "veterinary technicians" in most states and are legally qualified to assist veterinarians in many medical procedures. Veterinary assistants, who are not licensed by most states, but can be well-trained at facilities such as The School for Veterinary Assistants, are also becoming increasingly in-demand in the veterinary industry due to a wide range of treatments and services being offered to meet the higher expectations of pet owners in the United States.