Veterinary medicine

• ANATOMY OR SYSTEM AFFECTED: All
• DEFINITION: The healthcare and medical treatment of animals, both domestic (pets and livestock) and wild (native and exotic species), which includes preventive healthcare, sanitary and environmental management, and the treatment of diseases and injuries.

Science and Profession

Animals become sick, get injured, or fail to perform as well as they should, just as humans do. Humans, however, have developed a much more sophisticated medical expertise about themselves than they have about the wide variety of other animals. The basics of this medical knowledge apply to other animals, but the physiological differences of each of the many kinds of animal species preclude the application of human medical care. Much of veterinary knowledge has traditionally been concerned with a few common species, such as cats, dogs, cattle, sheep, goats, swine, horses, and some birds. Other species are receiving increasing attention, however, and their medical needs are becoming more widely acknowledged and better understood.

Most of the medical fields concerned with human health apply to veterinary health practice as well, including anatomy, anesthesiology and pharmacology, biochemistry, cardiovascular medicine, cell biology, dental medicine, dermatology, disease pathology, emergency and critical care, endocrinology, epidemiology, gastroenterology, genetics, geriatric medicine, hematology, immunology, internal medicine, microbiology, nephrology and renal medicine, neurology, obstetrics, oncology, ophthalmology, orthopedics, osteopathic medicine, otorhinolaryngology, physiology, psychiatry, surgery, and urology. There has been much progress in the veterinary applications of these fields. There has also been considerable progress in the application of the expertise, techniques, and equipment used in these fields to an increasingly wide variety of animal species. This development is attributable to both an improved knowledge of and interest in these other species and a growing ethical concern for this wider range of species.

Not only have humans become more knowledgeable about how to care for less common domestic and wild animals, it has also become more acceptable to do so. As a result, veterinarians have become involved with a much wider range of employment opportunities in government, business, universities, and zoological parks, although most are still in private practice and dealing with farm livestock, horses, cats, and dogs. Veterinarians also work in a wider range of locations—clinics, research laboratories, farms, zoological parks, and the wild. There are also more employment opportunities for veterinary technicians, paraprofessionals who assist the veterinarian or who carry out certain veterinary duties when the veterinarian is not available.

Veterinary medicine is both a distinct medical field and an extension of human medical fields. It deals with species quite different from humans, the degree of difference ranging from slight (such as with primates) to great (such as with birds, reptiles, amphibians, and fish). While medical doctors deal with only one species, veterinarians are concerned with a multitude of species. Therefore, medical doctors tend to specialize in a particular field, while veterinarians tend to specialize in particular kinds of animals. There are some similarities and many differences between human medicine and veterinary medicine, with one common ground being zoonoses—those diseases that can be transmitted between humans and other animals. These degrees of similarity and difference among species are a primary concern for the veterinarian and are one of the things that make veterinary medicine such an interesting subject.

Most veterinarians perform routine clinical work, both in the office and in the field, dealing with farm livestock, domestic pets, and racing horses and dogs. However, some are involved in other kinds of work. Veterinarians may work with exotic pets; exotic livestock, such as on ostrich or alligator farms; zoological park and aquarium animals; or laboratory animals. They may maintain healthy game herds and flocks, such as deer and turkeys; translocate wild animals from one area to another; work with teams doing scientific research that involves animals; help with efforts to save endangered species, either in the wild or in captivity; work with beached porpoises, whales, and other sea mammals; or advise government agencies concerned with animal-welfare issues.

In addition to treating sick and injured animals, veterinary medicine involves advising on preventive measures, making routine observations of individual animals or groups of animals, evaluating herd management, assessing environmental and housing conditions, assisting with births, and performing necropsies. Veterinarians working with laboratory animals, zoological park animals, native game species, or endangered species may also provide advice on reducing stress; assisting with propagation strategies, including various artificial propagation techniques; tranquilization; translocation techniques; the gathering of tissue samples; and other animal-welfare matters.

The control of epidemic diseases in farm livestock or native wildlife is also carried out by veterinarians. Diseases that may be introduced by imported animals, particularly exotic species, are of interest as well. For example, parrots imported for the pet trade are capable of transmitting diseases that could affect poultry, as are migrating native bird species. Imported exotic hoofstock can introduce diseases that could affect farm livestock, as could the importation of farm livestock from already infested areas.

For these reasons, species similar to those on farms and ranches, usually birds and hoofstock, are subjected to medical quarantines and other medical restrictions. The transfer of animals or animal products from one country to another by private citizens is strictly controlled. Diseases that can be passed to humans by animals, particularly those sold as pets, are closely monitored. Another problem involving both medical doctors and veterinarians is those diseases that can be passed from native wild animals to humans, either directly or through other host species, such as insects.

Veterinarians working in the field on medical problems involving native wildlife, imported exotic species, or endangered species are often on their own, working at remote sites and frequently carrying their clinics on their backs. Improvisation, creativity, and adventure are typically part of their practice.

In summary, while the application of veterinary medicine involves the same kinds of medical fields as those used in human medicine, the methods, techniques, equipment, medicines, and treatments are different. The degree of difference depends on the species and the area of operation, which ranges from urban clinics to rural farms to the wilds of remote wilderness areas.

Diagnostic and Treatment Techniques

Most medical fields are much better developed for use with humans than with animals because humans know so much more about themselves than they do about other animal species. Humans constitute only one of innumerable species—one that has been studied in depth for quite some time. Unlike human medicine, veterinary medicine is concerned with many animal species, each of which has its own physiological parameters. In addition, different categories of animals—mammals, birds, reptiles, amphibians, or fish—have significantly different body systems. These different categories and species must be treated differently when determining whether an animal is normal and healthy and when prescribing treatment for a sick animal.

The best-understood groups of animals are the ones that have been of concern to the veterinary profession for the longest period of time, namely farm livestock and pets. Other groups have received attention, including animals in zoological parks, laboratory animals, native wildlife, and endangered species. As ethical concerns have extended beyond the human race, more concern has been shown for the health of all animal species. There remains much to learn about the many species that are not dealt with on a regular basis by veterinarians.

The diagnosis and treatment of an illness or injury depend on the kind of animal being examined. Since the animal cannot tell its owner or the veterinarian what is wrong, it is up to the veterinarian to discover this information. The diagnosis is, therefore, particularly important. First, the veterinarian must analyze any abnormality. On a clinical level, this means a general physical examination, a special examination of the suspect system or organ, a special examination of the problem area, and a medical history, as well as laboratory tests and a comparison with peer performance standards. Second, if applicable, the veterinarian must analyze the pattern of occurrence of the abnormality in the herd; this process includes an epidemiological examination and an evaluation of general management, environmental factors, time of year, nutritional status, and genetics. The veterinarian then categorizes and defines the abnormality, prescribes a treatment, follows up on the treatment, and advises the owner on prevention.

The first step in providing care is knowing when an animal is sick. An injury is easier to detect, but it may still be difficult to determine the extent of the injury. Lack of performance may or may not be a medical problem. It is easier to determine when an illness is present in animals with which humans are very familiar, such as pets, horses, or livestock. It becomes more difficult with other mammals and birds, especially with fish, reptiles, and amphibians.

The species of the animal being evaluated must be known, along with the physiological parameters for that species. The medical history of the individual—and, if applicable, the other individuals with which it is associated, such as a herd—is also necessary. A clinical examination is then used to determine the current medical situation, supplemented by a laboratory examination and an epidemiological examination. These examinations include consideration of past diseases and treatments, nutrition, behavior, general appearance, skin condition, voice, eating habits, defecation and urination, posture, and gait; the inspection of specific body regions; a physical examination, including taking the animal's temperature and pulse; consideration of environmental factors, such as housing, source of water supply, sanitation, and chemical contaminants; and laboratory tests on specimen samples from the animal and the environment.

Based on this information, a diagnosis is made, and a treatment is prescribed. The diagnosis should provide information on the disease or injury, the etiology of the disease, and the clinical manifestation—that is, the severity or extensiveness—of the disease. The treatment may involve additional care, surgery, medication, a change in diet, or a change in the animal’s environment.

Follow-up on the treatment may also be necessary, as well as continued monitoring and reexamination. Medicines can have side effects, and multiple medicines can have synergistic effects. Another problem is that animals tend to care for themselves by licking, pulling at bandages, and other behaviors that can undo what the veterinarian has done. Also, animals are not able to say whether they are feeling better, although this can often be determined by observing the animal’s return to normal behavior.

Preventive healthcare is as important for animals as it is for humans. This type of care may involve vaccination shots, pills, proper nutrition, dental care, reduction of stress, exercise, sanitation and proper housing, the quarantine of exotic species, or simply observation of behavior.

Low performance may be a medical problem but it is difficult to detect because the problem tends to be a subclinical disease. The performance of livestock and racing animals may require the attention of veterinarians. The efficient performance of livestock is economically important to the farmer, and an assessment of a herd’s productivity is usually done by comparing its performance with a standard that is based on the known performances of peer herds. Productivity can have several meanings, including reproductive efficiency, the amount of milk or meat produced per animal or per hectare, calf survival rate, longevity, and acceptability or quality of the milk or meat at market. Low performance might be caused by a number of factors, such as inadequate nutrition, poor genetic inheritance, improper housing, stress, lack of herd-management expertise, subclinical diseases, physiological abnormalities, or anatomical problems.

Although some veterinarians specialize in a particular medical field, for the most part, a veterinarian has to be familiar with all medical fields in order to treat an animal. While these fields are basically the same whether one is treating a human or an animal, veterinary medicine is complicated by the fact that each species has different body structures and physiological parameters. Also, different equipment and techniques are necessary for applying these medical fields to animals. For example, the principles of anesthesiology are well understood, but applying anesthesia to a human is not the same as applying it to a dog, a horse, or an elephant. The gases and doses used, the equipment needed, and the procedures performed must be tailored to the particular kind of animal being treated.

Most veterinary work is carried out in the clinic, particularly small-animal practice, which usually involves cats, dogs, and other common pets. Large-animal practice, typically involving farm livestock and horses, is often done at specially designed on-site areas at a farm or ranch. Veterinary schools have both small-animal and large-animal clinics. While small animals are easily handled, large animals need pens, squeeze cages, tilting tables (able to tilt from a vertical position, in which the animal is strapped onto it, to a horizontal position), and other equipment to restrain them during the examination. Large-animal veterinarians working on a farm or ranch also use veterinary vehicles that are stocked with whatever the veterinarian normally needs. In rural areas, the animals requiring care tend to be too far away from the clinic for veterinarians to repeatedly return to the clinic for supplies while making rounds, so their vehicles are specially adapted as mobile clinics, either by the veterinarians themselves or by commercial companies.

Perspective and Prospects

Animal domestication developed around 8000 BCE. With humankind’s increasing dependency on domestic animals, it became necessary to care for their medical needs. The Code of Hammurabi, a legal code from Babylonia that dates to the eighteenth century BCE, mentions payments to animal doctors if they successfully care for an animal and punishment if they are not successful. Papyri from ancient Egypt contain the oldest known veterinary prescriptions (ca. 1900 BCE). The first veterinarian known by name was from India (ca. 1800 BCE). It was also in India that the first known animal hospitals were established, around 250 BCE. The Aztecs of ancient America also had animal doctors for the large royal animal collections. Ancient civilizations treated diseases with herbs and rituals; some surgical procedures were performed, and some injuries were treated. Medical instruments were crude, and care was based on magic and folklore. This was not unusual during a time when medicine, science, and religion were integrated into one limited body of knowledge. The fact that an effort was made to care for animals indicates their importance to these early societies.

While medical knowledge increased in ancient China and Greece, veterinary knowledge did not. In the Roman and medieval periods, practitioners simply compiled and transcribed what had already been done. Nevertheless, the advances made in medical knowledge—for example, the determination that diseases have natural rather than divine causes—would affect veterinary medicine as well.

The Renaissance brought about a renewed interest in many areas of study, including veterinary medicine. In particular, there was concern about farm livestock and horses because of their increasing economic importance to society. In addition, much of the medical research conducted during this time was done with animals. Advances in veterinary medicine at first coincided with those in medicine in general but were eventually made for their own sake. The first short-lived veterinary schools appeared in Spain around 1490, and the first modern ones appeared in Europe during the eighteenth century. It was not until the nineteenth century, however, that methodological observation and examination became the foundation for diagnoses, and veterinary medicine passed from the common practitioner to the academic or professional practitioner.

One significant effect of the growth of veterinary medicine and its acceptance by the general public has been the concept of animal rights, which has increased the provision of medical care to pets, exotic animals, and native wildlife. At the same time, veterinary knowledge has extended to amphibians, reptiles, and fish, as well as to a larger array of birds and mammals.

Bibliography

American Veterinary Medical Association. www.avma.org. Accessed 9 Sept. 2024.

Ballard, Bonnie, and Ryan Cheek, eds. Exotic Animal Medicine for the Veterinary Technician. 3rd ed., Wiley, 2017.

Ford, Richard B., and Elisa M. Mazzaferro. Kirk and Bistner’s Handbook of Veterinary Procedures and Emergency Treatment. 9th ed., Saunders, 2015.

Kahn, Cynthia M., ed. The Merck Veterinary Manual. 11th ed., Merck, 2016.

Latimer, Kenneth S., ed. Duncan and Prasse's Veterinary Laboratory Medicine: Clinical Pathology. 5th ed., Wiley, 2011.

Miller, R. Eric, and Murray E. Fowler, eds. Fowler's Zoo and Wild Animal Medicine: Current Therapy. 10th ed., Saunders, 2023.

Radostits, O. M., Clive C. Gay, Kenneth W. Hinchcliff, and Peter D. Constable. Veterinary Medicine: A Textbook of the Diseases of Cattle, Sheep, Pigs, Goats and Horses. 11th ed., Saunders, 2017.

Wallach, Joel D., and William J. Boever. Diseases of Exotic Animals: Medical and Surgical Management. Saunders, 1983.