A domestic animal has been artificially selected by humans for certain characteristics such as temperament or appearance. Since they have been bred for characteristics attractive or useful to humans, they are very different from wild animals. Our extensive experience with domestication of animals is bringing up many aspects which seem to better our understanding of animal health.

• Most domestic animals share with us, both the food and diseases of industrialized society. They are prone to allergies (horses allergic to grass), obesity, dementia, neurosis and even show signs of psychological illnesses. They also lose the instinct of avoiding poisons.
• Farm animals selectively bred for “productivity” are reared to add muscle even before their circulation and heart have developed. Chicken thus especially suffer circulatory problems, heart failure and weak bones and are in extreme poor health. Because they are fed with antibiotics, they colonize dreadful resistant forms of bacteria and hence such animals are a potential threat to humans who eat them. However, health of animals meant to be sold as food is of no concern to the breeder. They need to be alive till they are taken for slaughter.
• Wild animals born into captive environments such as zoos are nutritionally compromised. Though they may live longer, they are in poor health suffering from anaemia, fertility problems and eating disorders. They are susceptible to many diseases and usually die of cardiovascular disease.
• In addition to being precluded from hunting, foraging and other forms diet selection avenues, captive wild animals are restricted from social interaction and are thus denied the needed physical exertion that is critical for good health.
• Most intensely reared farm animals such as cattle, sheep and pigs are depressed and hence are prone to many pathologic conditions. Captive parrots and macaws are well known for self-abuse. These social birds used to living in flocks show signs of psychological illness in captivity due to confinement.