A number of agricultural species have been used for research into various types of tumors. Cattle and horses have limited use as models because their size makes housing difficult in a biomedical facility. Horses are used as models for asthma and for exercise and reproductive physiology. The alimentary function of the rumen and the dependence on the products of microbial digestion give rise to specialized metabolic functions in ruminants. Consequently, ruminants usually are not used as metabolic models for the human. Calves have been used for specialized cardiovascular surgical studies, e.g., development of artificial hearts. Sheep are of a size manageable in most biomedical facilities. Sheep have been used as models for a number of disease states, but perhaps the greatest use has been to study metabolism during pregnancy. Sheep have one or two fetuses and are large enough that catheters may be placed in veins and arteries to sample blood traversing to and from the fetus, the placenta, and the dam. Metabolic observations must, of course, be tempered by the fact that the sheep is a ruminant and the anatomy of the placenta is different from the human's. The possibility of Q-fever in sheep precludes its use in some biomedical facilities.
Was this article helpful?
If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.