Why 'hybrid vigour' in dogs is a joke  

Any litter of dogs, whether they be purebred or mutt is just a roll of the dice. Responsible breeders take the time to compare the pros and cons of the sire and dam to try to ensure that the puppies will be as close to the standard for that breed and as healthy as they possibly can be. They also do a plethora of health testing, from x-raying hips and elbows to rule out dysplasia, having their dog's eyes cleared to rule out progressive retinal atrophy and other eye defects, blood tests for Von Willebrands and ultrasounds for heart defects.

Mrs. Smith, with Fifi, the malti-poo down the street that got bred by Rex, the terrier cross next door, probably didn't even deworm the puppies before they went to their new homes. Because neither the sire nor dam has ever been checked or cleared for any of the above diseases, their chance of producing affected offspring is much greater than any other mating that has been checked.

Because most pet owners don't check their young adult mutts for these diseases, again, we have a series of puzzled pet owners wondering why their beloved dog passed away at 6 while catching a frisbee (heart defect), or why their 8 year old dog has suddenly developed a painful looking limp that they can't seem to shake (hip dysplasia). Yet, we still have people maintaining that their dog was a hybrid, therefore it had 'hybrid vigour' simply because someone said so and completely ignoring the fact that their dog passed away before it's time without any insight as to why this might be?

That's not to say that ALL pet owners don't do their dog's health clearances, but from the statistics available, the information isn't any more reassuring to those still clinging to the belief that because their dog is a mutt, it is healther.

If you look at the standing for at-risk breeds on the Orthopedic Foundation for Animals website ( http://www.offa.com/hipstatbreed.html ) you'll see that 'Hybrids' are #30 on the list of 148 Popular breeds for hip dysplasia. They are #45 for elbow dysplasia. #47 for patellar luxation. #1 for congenital cardiac disease.

Popular genetics may say that hybrid vigour has worked very well in humans (unintentional), in corn (intentional with years of study and genetic research on the topic), but quite frankly, breeding Dog Breed A to Dog Breed B to attempt to get a puppy with superior genetics is not only a crapshoot, it's about as unscientific as it gets.

In fact, since hybrid vigour can only really be proven for the first generation (but not always, at that), it means generations bred down from the results of that first generation will be just as riddled with genetic defects and diseases as any other dog.

Even then, it doesn't always happen this way. They might not even get to see those puppies grow up. If a dam was bred without being tested for STDs (Yes, dogs get them, too, I'll bet most pet owners didn't know that) the owner of the female might get to experience the joy (sarcasm, here) of watching an entire litter of puppies gasp, and slowly die over a period of days from Canine Herpesvirus. Or perhaps they lose the entire litter in utero from brucellosis. Even hybrids can contract an STD.

Purebred dogs aren't perfect, but purebred dog breeders can accurately assess size, temperament and appearance of their dogs. Too bad Mrs. Smith can't say the same thing.