Why do mixed breed dogs tend to have less health problems?

Answer 1

A mixed breed dog may not have less health problems than a pure breed. It is less likely to have a known problem, and it is less likely to have been inbred or line bred. Inbreeding or line breeding practiced by some dog breeders reduces the possible number of genes available and therefore weaknesses carried by recessive genes are more likely.

"Hybrid vigour" refers to the fact that if a dog is bred from a mix of breeds it may be less likely to have problems caused by a recessive gene that may prevail in one breed. For this to be likely, any mix of breeds will not do: the breeds must be selected from those that do not have similar prevalent problems. Also, with a mixed breed or mongrel of unknown ancestry, there is no indicator of potential faults that may show up in offspring.

Hybrid vigour may also apply in comparison to breeds that have been inbred. This happens when populations are isolated or small and/or become fashionable. Sadly, fashionable breeds and crossbreeds go through a sudden population growth and are exploited by people who do not look at potential genetic issues when selecting parents. The dogs are also less likely to be carefully selected as a suitable breed by the owners.

Answer 2

One advantage of owning a mongrel rather than a purebred dog is that mongrels are less likely to suffer from inherited medical problems that generally plague a certain breed, such as respiratory issues for Pugs or hip issues for Great Danes. Another advantage of mongrel dogs is that oftentimes one can adopt one for free or for a nominal fee as opposed to the hundreds, or possibly thousands, of dollars that a purebred dog generally costs.