Our pet causes
Owning a pet may have a variety of health benefits, but beloved animals also bring the threat of some illnesses into our lives.
The research associating pet ownership with health benefits goes back to the early 1980s. Without too much trouble, you can find study results linking lower blood pressure, improved recovery from cardiac disease, and even reduced rates of asthma and allergy in children to having a Fido or a Frisky in the house. Cats and dogs dominate the pets-for-health literature. Data on the benefits of consorting with other sorts of creatures are sparse to nonexistent.
Many of these studies have been cross-sectional snapshots, or retrospective, so it's hard to know whether animal companionship truly makes people healthier, or if people who are healthier to begin with are more likely to take on the responsibility of having a pet. It's a problem that bedevils a lot of health research: how to separate the effect of a behavior from the qualities of the sorts of people who have it.