Canine DNA Testing

DNA testing  is being used to tell an individual dog's breed.

Some genetics companies say they can tell mutt owners which breeds their dogs come from, for a fee of $60 to $125. The results, say the companies, can satisfy simple curiosity, provide clues to a dog's behavioral quirks, and even help identify breed-specific health problems.  Does it work?

DNA tests offered by four companies were used on one dog revealing that DNA isn't conclusive—all four labs came back with different results. "DNA is inherited randomly from each parent which makes every dog unique. This is why a dog's appearance may look different than the breeds detected in the DNA test."

The big difference is the number of breeds in each laboratory's database.  Among the breeds  some have and others don't is the American Staffordshire terrier/American pit bull terrier.

Dog DNA testing is a relatively new field so canine genetics is an inexact science. To locate the genetic markers that might differentiate a breed—markers that control for size, for example -- companies take samples from purebreds with established pedigrees. Depending on how common the breed, they might sample anywhere from a handful of dogs to hundreds ...estimates given say it costs a minimum of $20,000 to get a new breed into the database.

But geneticists say the DNA of dogs even within a given breed can vary widely depending on the country they are from. In addition, breeds within the same group -- such as terrier -- can be very similar genetically. Also, a single dog has billions of bases, building blocks of the genome, and these DNA labs only look at a few hundred. What's more, there are thought to be as many as 400 dog breeds world-wide -- roughly 160 of which are recognized by the American Kennel Club -- and it would be impossible to know for sure that a breed has a unique genetic sequence unless every one of the breeds was analyzed.

Breeds that show up as contributing to a large part of your dog's DNA are likely to "accurately reflect a dog's composition," says Urs Giger, a clinical geneticist at the University of Pennsylvania School of Veterinary Medicine. But of the breeds that come back in amounts of less than 10%, he says, "you can't be sure" that your dog's makeup actually contains that breed.

One Vet, says the list of breeds it screens for includes the most-common ones, but adds dog owners should check the list before buying the service, in case the breeds they suspect their dog has isn't on it.

When one lab scanned the subject mutt's DNA, no one breed emerged as dominant, so the software looked for the closest matches. The fact that it came back with Boston terrier was telling, since that breed is in the same family as the American Staffordshire terrier, which is not in the database.

Nearly $400 later, the breed of  the subject dog is remained uncertain.

Likely Bella and Lizzy are American Staffordshire Terriers as described by their Vet but only God knows for sure.

*source : PAULA SZUCHMAN, WSJ