An article from the LA Times;

How dogs can help unravel genetic diseases in people

By Rosie Mestel Los Angeles Times

August 15, 2012, 3:14 p.m.

Dog lovers may be interested in an article published this week in the New England Journal of Medicine: It highlights the discoveries scientists are making about diseases that various dog breeds are prone to -- and how those findings can benefit human health as well as that of canines.

It’s written by longtime dog genetics researcher Elaine Ostrander of the National Human Genome Research Institute.

The discoveries are possible because of several things: First off, both the human genome and dog genomes have been sequenced. (The breeds chosen for the first round of dog DNA sequencing were a standard poodle and boxer, should you be curious.)  

Secondly, dogs have been intensively bred into distinct breeds, and in the case of purebreds (though not my black mutt Nightshade; who knows where she came from?) their pedigrees are very well known. Often, the breeds are descended from just a few animals, so they can be very inbred as well.

The intensive selection over the decades and/or centuries for traits of body shape or hair color has also inadvertently selected for genes that foster diseases. And so Bedlington terriers are prone to copper storage diseases, Doberman pinschers are prone to narcolepsy, and so on.

Here is where some lemonade gets made out of that sad lemon: It’s far easier in many cases for scientists to track down genes associated with, say, a cancer or vision disorder in dogs than it is in human beings, Ostrander writes.

That’s especially true when a disease could stem from one of several genetic defects. If you study a bunch of people with the disease, the underlying genes involved will probably be a mix and the results will be too cloudy for scientists to make sense of. But in an inbred dog strain prone to a disorder, the underlying cause is far more likely to be rooted in one specific gene.
And that means scientists can find it. Once they’ve found it, they can then go back and see if the same holds true for some human beings.
Some examples Ostrander cites of gene-influenced disorders in dogs shedding light on diseases in human beings:

--A syndrome called RCND that causes kidney cancer and skin growths in German shepherds was pinpointed to versions of a gene called folliculin. That same gene, it turns out, is involved in a human disease called Birt-Hogg-Dube syndrome.

“The single, large dog pedigree was collected and genotyped in a fraction of the time it took to collect and characterize the many necessary human pedigrees,” Ostrander notes.

--Epilepsy crops up in a lot of different dog breeds, and scientists have found a different underlying genetic cause for miniature wire-haired dachshunds versus Lagotto Romagnolo dogs. Extending the study to other breeds of dogs could expand the list of genes that can be involved in epilepsy, allowing scientists to get a better handle on all the different ways that it can crop up in people.

-- And here's a gene therapy example. Leber’s congenital amaurosis type 2 is a progressive retinal atrophy in dogs that leads to blindness. It results when a gene called RPE65 is nonfunctional. The disorder was successfully treated by introducing a functional version of the gene to a dog, carried on a virus. The same genetic disease occurs in people, and “humans with Leber’s congenital amaurosis are now being successfully treated for the disorder,” Ostrander writes.

I see many dogs with epilepsy. In almost all cases we never understand what causes the seizures to start. Sometimes we can "control" the pets seizures with medications. But I always warn my clients that for as much as we are hoping that the medications control the seizures, in the end, if the seizures are minimized the drugs wreak utter havoc on the internal organs (most noteably the liver), and if these pets don't die from their seizures they will die of liver failure. Epilepsy can be a difficult, frustrating, devastating, and an expensive disease to just "control."

Every vet knows, (and most breeders) that there are certain disease's that we see over represented in some breeds. Dobies with heart diease, neurological diseases, Westies with skin, urinary stones, Dachshunds with back problems, white bulldogs and Boxers with skin disease, beagles and cockers with ears, the entire brachycephalic cascade of facial deformities, King Charles with heart disease, German Shepherds with allergies, hips, immune diseases, the list goes on, and on.

Maybe in an effort to unravel the mysteries of why human's get some of these diseases we can also figure out how to cure or prevent them from affecting our pets.

Until then my best piece of advice is to mutt-up those breeds. I know I am causing heart palpitations in the Westminster-wanna-be crowd, but it's true. I am not treating 1 mutt with epilepsy right now, BUT I am treating about 10 other pure breds.

For a good text book on this subject I recommend;

http://www.amazon.com/Breed-Predispositions-Disease-Dogs-Cats/dp/1405180781/ref=sr_1_1?ie=UTF8&qid=1345309165&sr=8-1&keywords=pet+breed+disease

Available through Amazon. To look at this book follow the link and then take a tour of the book.

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