Rabbit Genetics EssayThe similarity between the physiology of rabbits and humans makes the rabbit a good model for research into human disease. The most prevalent types of rabbits are cottontails and European rabbits. Domestic rabbits are tame assortments of European rabbits. The Californian, Florida White, and New Zealand White are the most common breeds used in research.
Until 1912 rabbits were classified as rodents. Scientists discovered that the two types of animals differed in several distinct anatomical ways. Rabbits, for instance, have a second pair of upper incisors, known as “peg teeth,” that are found behind the two main visible incisors in the upper jaw. Rabbits have elongated hind legs adapted for moving at high speeds over open areas. Rabbits generally move in a hopping motion. They also have webbed toes to keep them from spreading as they hop.
Rabbits have flexible necks, which allow them to turn their heads more than rodents. Their spines are long and fragile and susceptible to fractures if the animal is held improperly. ResearchThe ability to produce tumors in rabbits makes them useful models to study chemo/immunotherapy, as well as immunoprevention of certain cancers. Cholesterol studies: Rabbits have been used to test Probucol, a drug that lowers blood cholesterol and retards the development of hardening of the arteries. Eye ear and skin studies: Rabbits are used to study middle and inner ear infections, which affect millions of infants and children each year.
Rabbits are also used to study Entropion, a condition in which the eyelashes are turned inward, as well as Glaucoma, which often results in blindness. Rabbits are used in eye and skin irritation tests to develop appropriate procedures for handling certain chemicals and to predict the toxicity of accidental exposure. More than 10,000 blind or visually impaired people have benefited from corneal transplants, possible only because of hundreds of trials on rabbits. Drug metabolism: Rabbits have been used to study the effects of marijuana on the central nervous system.
Pregnacy TestPresently a woman who wants to find out if she’s pregnant need only make a quick trip to the local drug, grocery, or convenience store; purchase an over-the-counter home pregnancy test kit; perform a simple test; and she’ll know the results within a matter of minutes. Not so long ago, however, it was not nearly as quick or easy: Awomawho thought she might be with child had to schedule an appointment with her doctor, make a trip to his office, give a urine sample, go home, then spend an anxious couple of days waiting for the office to telephone with the test results. In the movies and television, a positive result was usually revealed by having a character burst into a scene and announce dramatically, “The rabbit died “. But why a rabbit? And why did it die if the woman was pregnant? The origins of the “rabbit test” lie with the discovery in the 1920s that a woman starts producing a hormone known as human chorionic gonadotropin (hCG) shortly after a fertilized egg implants itself in the uterine wall. It was later discovered that the presence of hCG causes the placenta to produce progesterone after implantation.
Production of that chemical was necessary to prevent rejection of the developing embryo. In 1927, medical researchers found that not only is hCG present in the urine of pregnant women, but that female rabbits injected with urine containing hCG would, within a few days, display distinct ovarian changes. Thus the “rabbit test” was born, and with it the misconception that the rabbit’s death was an indicator of a positive result. In those early tests, the rabbit always died, because the animal had to be killed before its ovaries could be examined. Later refinements to the test enabled researchers to inspect the ovaries without having to kill the rabbits first.
Modern pregnancy tests are still based on measuring the amount of hCG present in urine, but they do so directly, without the need of an animal intermediary to serve as a test subject. Blood can also be tested for hCG; in fact, this type of test is more accurate and can be performed earlier in the pregnancy, but urine tests are still used in home pregnancy kits because they’re much easier .
