ANIMAL MAGIC

HOW animals are used in medicine: Cow tissue is used to make new heart valves CERTAIN types of animal tissue have been used for many years to replace defective human parts. For instance, a cow’s pericardium — the ‘bag’ in which its heart sits — is often used to make replacement heart valves for patients whose own valves are diseased or malfunctioning, putting them at risk of heart failure.

The pericardium is ideal for the job because it is tough, durable and can be stripped of all bovine DNA, using the chemical glutaraldehyde. Pericardial tissue is also relatively cheap and readily available. Pig tissue is also used.

Animal-based replacement valves have become more popular as they’re less likely to lead to blood clots than manmade metal versions — which the body treats as a foreign material, triggering an immune system attack and inflammation around the implant.