Repetitive behaviors, often seen in human neuropsychiatric disorders such as autism and obsessive compulsive disorder (OCD), have not been studied extensively, even though such compulsive behaviors occur in multiple species including dogs. Several similarities have been found between compulsive behavior in dogs and humans, suggesting that they may share a neurobiological basis.

Many dog breeds exhibit spontaneous compulsive behaviors, often diagnosed as canine compulsive disorder, which can include repetitive pacing, tail-chasing, chasing shadows or lights, freezing and staring. Researchers led by Hannes Lohi of University of Helsinki in Finland looked for possible associations between tail-chasing and environmental factors and personality. The team conducted a questionnaire study of the owners of nearly 400 bull terriers, miniature bull terriers, German shepherds and Staffordshire bull terriers, breeds in which compulsive tail-chasing is most common (PLoS One 7, e41684; 2012).

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Tail chasers were more likely to suffer from other compulsive behaviors, including freezing or trance-like behavior, than the non–tail chasers. The team hypothesized that the trance-like “staring episodes” seen in these dogs could be analogous to similar behaviors in humans with autism spectrum disorders. The frequency of tail-chasing behavior showed a large variation in the dog populations, similar to OCD, in which symptoms and co-occurrence of compulsive behaviors vary greatly.

Early separation from the mother and poor maternal care of the puppy were found to predispose dogs to tail-chasing. Childhood trauma or stress has been associated with OCD, suggesting that both dog and human compulsive behaviors have similar environmental causes. The scientists also found an association between tail-chasing and personality, particularly in the male dogs they studied. Tail chasers were generally shyer and less aggressive towards humans than non–tail chasers. Shyness in dogs shares characteristics with behavioral inhibition, a human temperament style involving restraint, withdrawal and avoidance of new things, that is characteristic of many OCD patients.

Tail-chasing behavior was found to be connected with the dogs' nutrient intake: dogs that received dietary vitamin and mineral supplements had less tail-chasing compared to the dogs not receiving any nutrients. “Interestingly, similar preliminary results have been observed in human OCD,” said Katriina Tiira, first author of the study, in a press release. Vitamin B6 in particular was found to be beneficial to the dogs.

The study suggests that dogs with canine compulsive disorder offer an excellent animal model for studying the genetic background and environmental factors associated with the human compulsive behaviors seen in autism and OCD.