Study: Canine Compulsive Disorder Brings OCD Into Focus

Earlier this week we learned that Toxoplasmosis, the cat-transmitted parasite that many of us have, is connected to suicidality. Today, tail-chasing hounds offer insight into understanding origins and treatments for obsessive-compulsive disorder in people.


PROBLEM: Obsessive-compulsive disorder is, it turns out, a cross-species problem. The analogous version in dogs is called canine compulsive disorder and includes "excessive tail chasing (TC), light/shadow chasing, and flank-sucking." Basically, it's hand-scrubbing and nail-biting for quadrupeds. Ergo, scientists at the University of Helsinki in Finland devised a study to explore some provocative genetic and environmental influences for this behavior using a cohort that has a particular advantage over humans: For dogs, owners are omnipresent and tend to keep their pets honest when it comes to data reporting.

METHODOLOGY: The researchers collected surveys on one specific symptom -- tail-chasing -- from the owners of 368 dogs, representing four different breeds. This last bit is important: the authors wanted to figure out as much as they could about what might be genetic (things that, say, a Bull Terrier is known to do) versus environmental (your German Shepherd is acting strangely). Questions revolved around frequency of behavior, as well as other factors including nutrition, when the dogs were neutered, and, yes, their relationship with their mothers. In addition, 181 DNA samples were gathered to further examine genetic components.

RESULTS: Dog lovers might be relieved to know that factors such as amount of exercise, time spent alone at home, and various iterations of relationship-with-owner didn't seem to influence CCD. The maternal bond, on the other hand, turned out to live up to its mighty reputation. Canines who were separated early from their mothers or neglected by them were more likely to have CCD.

Lending heft to the influence of genes, CCD prevalence varied by breed. It did not, however, vary by gender. Males and females were equally afflicted, with one exception: Dogs who had been neutered tended to have less CCD overall, and that effect was most marked among females.

Living with children or other species of pets seemed to mitigate the problem as did, surprisingly, nutrition. Dogs who received dietary supplements were less likely to have CCD, and even among the ones who did have the disorder, those who were getting the extra nutrients exhibited the behavior less often.

CONCLUSION: Both genetic and environmental factors appear to affect dogs' tail-chasing behavior. Among the latter, early trauma, hormone levels, and nutrition play noteworthy roles.

IMPLICATIONS: Not only do canines and humans have plenty of genes in common (75% of those we've identified, so the prospects of sharing certain genetic traits are good), but they also tend to inhabit the same kinds physical and psychosocial spaces (we live with dogs; hey, we all love to play fetch). In other words, there's a certain logic to reading these results with an eye toward human behavior, which is exactly what these researchers did.

It's likely that nobody needed to tell you that childhood trauma can lead to adult anxiety. The American Psychological Association and a host of existing research have that one covered. More novel, though, is the possible connection between hormones -- specifically fluctuations in estrogen and progesterone -- and OCD in females. This area, as the authors note, is ripe for future study.

Also worth attention is the discussion of which vitamins and nutrients were found to be effective in influencing the compulsive behaviors. The findings echoed those from earlier human studies. Researchers were able to rule out Omega-3 and 6 (important, since they're believed to have other mood benefits), and narrow the source of the benefit to magnesium, B5, B6, B12, and C, with C and especially B6 showing the most robust results. Vitamin B6, the researchers point out, is responsible for the metabolism of a number of mood-related neurotransmitters, including dopamine, serotonin, and GABA. B6 can be found in fortified breads and cereals, fish, and bananas, among other foods.

SOURCE: The full study, "Environmental Effects on Compulsive Tail Chasing in Dogs," is published in the journal PLoS One.