Picking a dog is a huge decision. Since you'll be spending the next decade or more with him, you need as close to a perfect fit as you can get. So much has been written about the energy and temperament aspects of this decision, but the question I'm most often asked is, "What is the healthiest breed?" And my answer to that question is always the same: It isn't a breed at all but simply a 30-pound brown mutt.
Mixed breeds are generally healthier
Because of what's known as "hybrid vigor," the midsize mixed breed is, on average, the healthiest dog. Hybrid vigor derives from the idea that the more breeds in a dog's genetic mix, the less likely it is that the genetic problems of purebreds will manifest themselves. Of course, I see very healthy purebreds and very unhealthy mixes, but if you want to go with the odds, pick the mix every time.
Expensive designer breeds
Attempts to bridge the gap between purebred looks, predictability, and mutt health--and come up with something completely new--have resulted in "designer breeds." These are the Puggles, Labradoodles, Maltipoos, and the like. They're intentionally created mixes that, while not purebred, can still maintain some of the expected traits we look for in a purebred and have some of the advantages of hybrid vigor as well. These dogs, as a rule, do seem to me to be healthier than some of the pure breeds, but they can be expensive, especially when compared with a mixed breed from a rescue or a shelter.
You get the dog you need
As much as I love mutts, a mixed-breed dog isn't for everyone. I just helped my mother buy an English springer spaniel puppy. Springers tend toward a range of genetic problems, from joint disease and rage syndrome to horrible allergies, but with the right leadership they're wonderful dogs, and this was the right choice for her.