Improvements in the rabbits' health through better nutrition and sanitation has made the raising and maintenance of rabbit populations easier, making them increasingly useful as a research tool. These improvements to the way that we keep rabbits are largely due to the knowledge of rabbit physiology gained through medical research.
The general physiology of rabbits is similar to that of humans, and like mice and rats, rabbits suffer from many diseases with human equivalents. Young rabbits often die from a disease called mucoid enteritis, which resembles cystic fibrosis and cholera. Rabbits are therefore used as models which can contribute to our understanding of these illnesses. Historically, Louis Pasteur used rabbits to develop his rabies vaccine and the rabbit has been important in the study of cardiovascular disease, particularly hypertension and atherosclerosis.
Studies in rabbits are key to many aspects of medical research, including cancer, glaucoma, ear infections, eye infections, skin conditions, diabetes and emphysema.
One of the most common uses of rabbits in the laboratory is for the production of antibodies, used to detect the presence or absence of disease and for research into infectious diseases and immunology. Antibodies are a key component of the adaptive immune system – the branch of the immune system which specifically recognises a foreign organism. They are complex molecules which can only be produced by the immune system of a living animal, and which recognise and bind to very specific protein sequences.
To produce antibodies the rabbit is injected with a protein sequence taken from the disease-causing organism to be studied. New Zealand white rabbits are generally used, as their large size ensures that plenty of antiserum is produced. Antibody is produced by the rabbit’s immune system, and the progress of antibody production is monitored by taking small samples of blood at regular intervals. Once a sufficient level of antibody has been produced, blood is then taken from the rabbit under anaesthetic. The antiserum from a single rabbit keeps for a long time, and produces a large amount of antibody, which is often used for several years. There are currently no alternatives to using animals for antibody production, but there is ongoing research into developing a suitable method.
The rabbit has provided an excellent model system to simulate the response of human tissue to the radiation produced by surgical lasers. Examples of laser advancements made possible by research on rabbits include eye surgery and the dissolving of plaque build-up on the walls of arteries.
The genetic condition familial hypercholesterolemia causes blood-cholesterol levels three to seven times higher than normal in humans. High cholesterol causes atherosclerosis – a build up of fatty deposits in the arteries which greatly restrict blood flow, and those born with this condition usually die of heart attacks in childhood.
The Watanabe rabbit suffers from fatally high blood-cholesterol levels due to a genetic defect, which mirrors the fatal human condition and they suffer heart attacks by the age of two. These rabbits are used as a model to provide better treatments for children with this disease, and for general research into high cholesterol. Research using these rabbits has included the development of an artificial liver to remove excess cholesterol from the blood of children suffering from hypercholesterolemia.