Pig

Pigs, or swine, are increasingly appreciated as excellent models for medical research. Among their advantages as research models are their short reproductive cycle, ease of breeding, large litter size, diversity of gene pool and early maturity. In addition, pigs and humans are similar in many aspects of both infant and adult anatomy, physiology, biochemistry, pathology and pharmacology. Because there is no placental transfer of antibodies to the developing pig fetus, newborn piglets lack maternal antibodies, making them good for studies of the mechanisms of immunity.

The hairless, abdominal skin of the pig has an almost human texture, permeability and thickness, affording researchers an excellent model for dermal research. Pigs were used, for example, to develop and test the patches which travelers wear on the skin to prevent motion sickness.

Many treatments and drugs for skin diseases, including therapy for severe burns, have been developed in pigs. Research into how wounds heal has also benefited from the contributions of swine, making them invaluable tools for researchers in plastic and reconstructive surgery, as well as other areas.

Swine have been used extensively in nutrition studies. Because they can suffer from gastric ulcers, they are widely used in ulcer research.

Pigs are also useful to medical researchers studying cardiovascular problems. In general, the cardiovascular and integumentary systems of miniature swine are more biologically similar to humans than those of any other animal. This similarity is most marked in the anatomy and physiology of the heart, and pigs have been useful in models of cardiac surgery, including heart transplantation and pacemaker studies.

Their role in the testing of cardiovascular drug treatments is well documented, and they can be good models for studies of stress and its relation to such disorders as hypertension. Pigs have shed light on the relationship between exercise and coronary physiology and health.

As early as 1775, pigs were shown to develop atherosclerosis as a natural part of aging. Normal, healthy swine are known to develop spontaneous atherosclerotic plaque similar to that seen in humans. This disorder develops more rapidly in pigs than in humans and can be increased with feed containing high levels of fat and cholesterol.

This makes them a model of choice for studying the role of diet in development of atherosclerosis. It is studies like these that have taught Americans of all ages to reconsider their dietary habits in order to prevent heart disease.