This week's stories from New Scientist available online. Veterinary scientists say thin sow syndrome, as the illness is known, is an emerging animal welfare problem. But studying the illness could speed up the search for drugs to treat human eating disorders.
Farmers use selective breeding to produce animals that are muscular and lean.
John Owen of the University of Wales in Bangor says these programmes can produce pigs prone to symptoms that resemble anorexia nervosa in people. The pigs affected are usually young females. They don't eat enough to maintain their body weight, are hyperactive and may not go on heat. It seems that the pigs have mutations in a gene for the ryanodine receptor, which regulates the flow of calcium ions across cell membranes. These mutations are linked to leanness and susceptibility to stress.