Chihuahua (dog breed)

Around half an hour of exercise a day is enough, the lowest need on this list, and many live well into their teens. A Chihuahua is bold and loyal and can learn to accept time alone, but it often bonds hard with one person and barks at noises, so socialise it early with neighbours and other dogs. Health is where to be choosy. Dental disease is very common in such a small mouth, kneecaps can slip, and the Royal Kennel Club has added the breed to its breathing-test scheme, so look for parents with longer muzzles and avoid merle colouring, which carries hearing and sight risks.