Tropical birds require a different climate as well as different foods than say a Malamute sled dog. It is more holistic to give them what they want and need. It takes at least 2-3 generations to remove the bad effects of inbreeding or weak traits. Start healthy if you can. Many animals with an unhealthy past can become healthy, it just takes more work.
Animals are very sensitive to our stress and tension.
In general, try to make your own recipes rather than using a cooked and processed commercial food. When exercising outdoors it is obviously important to protect pets from automobiles, vicious animals and other hazards. Humans can get boring sometimes. The closer animals are to a functional form, the healthier they will be. Animals that have been taking long-term medications usually have secondary conditions from the drugs that may be harder to reverse than the original condition.