DaySleepers gave some good information.
The age of the sire is just one piece of the longevity puzzle. You also have to take health into consideration. Since I'm most familiar with Dobermans, I'll start there. As a breed, dogs have a more than 60% chance of developing Dilated Cardiomyopathy. It's a very serious heart condition that can cause either congestive heart failure or sudden death due to arrhythmia. There are currently two genetic tests for known markers. The test results can be clear (-/-), affected (+/+), or carrier (+/-). Sounds cut and dried, right? Breed clear dogs to clear or carriers, and DCM goes away... except that it doesn't. There are dogs who are genetically clear for both mutations that develop DCM. There are dogs that are genetically affected that never develop it, and live into their teens. It gets even more complicated... Dogs who have died young of DCM have produced long-lived offspring. Dogs who lived into their teens without developing it have produced offspring that died young from it.
And like DaySleepers said, narrowing your criteria to only one thing dramatically reduces genetic diversity in your breeding stock, which leads to other problems. There are some breeds that are severely lacking in genetic diversity, which makes some health problems very hard to get rid of because of closed stud books and unwillingness to outcross or open the studbooks to bring in new lines. LUA Dalmatians are a good example. Their main health problem was isolated to one gene. A single outcross to another breed (Pointer) created dogs that were incapable of having that problem, because they all had a normal gene. The puppies from that litter were crossed back with Dalmatians for several generations to the point that, other than not carrying the defective gene, were genetically considered purebred Dalmatians. Yet the AKC parent club fought tooth and nail to prevent them from being registered as Dalmatians. After thirty years, they finally allowed them to be registered, but only with a LUA marker in their registration number. Contrast that with Basenjis, who also had a serious health issue caused by a single gene. A group of breeders went to Africa, and imported dogs straight from the Congo bush. The club voted to not only open the studbook for direct imports, but even changed the breed standard to allow the "new" color that came with the imported dogs.
The age of the sire is just one piece of the longevity puzzle. You also have to take health into consideration. Since I'm most familiar with Dobermans, I'll start there. As a breed, dogs have a more than 60% chance of developing Dilated Cardiomyopathy. It's a very serious heart condition that can cause either congestive heart failure or sudden death due to arrhythmia. There are currently two genetic tests for known markers. The test results can be clear (-/-), affected (+/+), or carrier (+/-). Sounds cut and dried, right? Breed clear dogs to clear or carriers, and DCM goes away... except that it doesn't. There are dogs who are genetically clear for both mutations that develop DCM. There are dogs that are genetically affected that never develop it, and live into their teens. It gets even more complicated... Dogs who have died young of DCM have produced long-lived offspring. Dogs who lived into their teens without developing it have produced offspring that died young from it.
And like DaySleepers said, narrowing your criteria to only one thing dramatically reduces genetic diversity in your breeding stock, which leads to other problems. There are some breeds that are severely lacking in genetic diversity, which makes some health problems very hard to get rid of because of closed stud books and unwillingness to outcross or open the studbooks to bring in new lines. LUA Dalmatians are a good example. Their main health problem was isolated to one gene. A single outcross to another breed (Pointer) created dogs that were incapable of having that problem, because they all had a normal gene. The puppies from that litter were crossed back with Dalmatians for several generations to the point that, other than not carrying the defective gene, were genetically considered purebred Dalmatians. Yet the AKC parent club fought tooth and nail to prevent them from being registered as Dalmatians. After thirty years, they finally allowed them to be registered, but only with a LUA marker in their registration number. Contrast that with Basenjis, who also had a serious health issue caused by a single gene. A group of breeders went to Africa, and imported dogs straight from the Congo bush. The club voted to not only open the studbook for direct imports, but even changed the breed standard to allow the "new" color that came with the imported dogs.
