Here's a special guest post by Pamela King, a Northeastern University journalism student interning with NOVA's web team this semester. To read more of Pamela's work, visit her portfolio blog!

What can dogs do for us? Apart from companionship and the tasks of the occasional watchdog or service dog, canines seem to be the sole evolutionary beneficiaries of their relationship with their best friend, man. Stephen Budiansky even goes so far as to describe dogs as social parasites in his book, The Truth About Dogs, an excerpt of which appears on the companion web site for NOVA's Dogs and More Dogs.

But a recent study published in Molecular Psychiatry indicates canines might serve a purpose beyond being our cute, cuddly friends - dogs could provide insight into human mental health.
Researchers watched as 92 Doberman pinchers exhibited compulsive behavior much like that of humans who suffer from obsessive-compulsive disorder, or OCD. Whereas OCD behaviors in humans might range from excessive hand washing to self-mutilation, canine compulsive disorder, or CCD, manifests as excessive sucking, pacing and grooming to the point that the behaviors affect the dogs' ability to function.

A surprising discovery followed an analysis of the dogs' DNA. The conductors of the study found the occurrence of CCD in the Dobermans was associated with the appearance of a protein known as CDH2 on canine chromosome 7. The study is the first to identify a genetic indicator for animal compulsive behavior. The implications of this finding are that CDH2 and other proteins might be associated with human obsessive-compulsive disorder.

Concerns that dogs experience these behaviors because of their relationship with humans do exist. A 2002 study conducted at the University of Pennsylvania concluded that CCD does not seem to be a result of social confinement or a lack of training and household stimulation. However, most of the dogs affected with CCD had some characteristics in common. Most had been obtained from breeders, lived in households with two or more humans and had some formal training, indicating that something about the relationship between human and dog could cause genetically-predisposed canines to exhibit symptoms of CCD. But a definitive link between human interaction and CCD remains unclear.

The type of protein identified in the study has already been linked to autism-spectrum disorders, which often involve compulsive behaviors, and such an indicator for OCD could be a catalyst for a better understanding of the disease as well as improved prevention and treatment methods for at-risk humans and dogs. Researchers are now conducting studies to find out whether the same protein indicates risk of OCD in humans. According to an article
by Elinor Karlsson and Kerstin Lindblad-Toh, humans share many other diseases with dogs, including cancer, diabetes and epilepsy. Gene mapping in canines could provide us with insight on these diseases as well.

Perhaps the close companionship between dogs and humans Budiansky describes could in fact be scientifically beneficial. Our close connection with a genetically similar species provides us an opportunity to study the diseases we have in common.

User Comments:

Very interesting. I am definitely passing this on to some of the dog-lovers that I know.

I was expecting to the study to be about how companionship of dogs benefit human mental health, and was pleasantly surprised to see a more unexpected topic of research.

Thanks!

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