I'm hoping you'll write about this again, Dr. Coates, when the article is published in April's issue of American Naturalist.

As the owner of three large breed dogs, I'm very interested in what they find out!

I have always thought that large dogs had a shorter life span because being large was harder on the heart. Interestingly, the article didn't mention that at all.

Are there any statistics regarding the cause of death for dogs, separated by large vs. small?

I found it interesting that this article puts forth the idea that a large breed dog has a lot more growing to do in roughly the same time span as a small breed, thereby creating a lot more room for error in cell replication (cancer, for example).

Almost 12 years ago, we and our friends each adopted a German Shepherd/Lab-mix puppy from the same litter. Their dog Sammie received the same excellent vet care as our Sheba throughout his life (as our vet makes house calls, many times we would simply have him come to one of our homes and see both dogs in one visit. We each had our pet neutered/spayed in the same month, made sure physicals, vaccinations, heartworm, flea & tick meds were current, etc.

The only difference that I can see is that we started Sheba out on a quality slow-growth large-breed puppy food and kept her on it for about 18 months. Sammie was fed a popular puppy food for about 12 months before switching to an adult formula. Sheba is female and, as such, would be somewhat smaller than Sammie anyway - but as they matured, Sheba remained a rather "petite" shepherd - about 63 lbs. Sammie weighed around 85 lbs.

My friends lost their beloved Sammie a week ago. He was diagnosed with degenerative-myelopathy about three months earlier and got worse quickly. He lost the use of his back legs and developed tumors all over his body. When he started showing signs of discomfort and trouble sleeping, my friends made the heartbreaking decision to have him euthanized.

Sheba shows no signs of the disorder, although the latest research indicates it is genetically transmitted. At almost 12 years old, she has slowed down a bit, but still shows great joy in chasing balls, leaping in the snow, and going for romps. Our vet checked her out last week and gave her a clean bill of health.

Is it possible that slowing the growth of larger breeds can somewhat mitigate the premature aging effects of being a large breed dog and thereby encourage a longer, healthier lifespan?

It is my understanding that DM is a genetic condition.

Within any litter of puppies, it is a crap shoot which ones will inherit the gene and which ones will not.

Genetic testing is available at the OFA website for DM. It's a simple saliva swab.

Personally, I kinda doubt that the food that was fed as puppies made any difference in this case. But, hey, I'm no expert, just someone who's looked into DM a fair amount, since it does occur with fairly low frequency in the breed I'm involved with.