As someone with a dog in my life, I couldn’t ignore that heading in the Science news alert that hits my in-tray each Friday. Of course, it couldn’t possibly apply to my little Ben :-)
OCD = Obsessive-Compulsive Disorder - an anxiety disorder; according to the Nationaal Institutes of Health website I linked to here, people suffering from it typically have recurring, unwanted, anxiety-generating thoughts (the ‘obsessive’ part of the syndrome) &/or repetitive behaviours that may reduce the anxiety (the ‘compulsive’ aspect). Now, I know that in captivity some animals can exhibit quite pronounced obsessive behaviours – pacing, licking, chewing inappropriate objects – so I was interested to read the article itself. It’s a profile of a vet, Nicholas Dodman, who does a lot of work with dogs who demonstrate a range of behavioural problems, at least some of which could be described as obsessive or compulsive.
For example, Holden & Travis mention him visiting a Doberman pinscher which compulsively licks the stump of an amputated leg; a very agressive ‘Australian shepherd’ (a kelpie?) who’s on prozac to settle her down, & a golden retriever that whines whenever his owner goes out of sight (which sounds a bit like separation anxiety). And you get cats that clean themselves compulsively, birds that pluck their own feathers, & so on. Instinctive behaviour gone awry. (Apparently some humans are into compulsive hair plucking, which carries the name trichotillomania – where tricho- means ‘hair’. I must confess to a sneaking fondness to words like this…)
Now, you could argue that some of this might be due to dogs being left alone while the owner’s at work, reflecting the fact that dogs really aren’t solitary animals. (Which is why Ben goes to doggy day care several days a week, & comes back happy, very well socialised, & usually wet from playing in the paddling pool.) But whatever the cause, the dogs & their owners are obviously in need of help & advice on ways to improve their lives. In many cases this may be something like enrichment (one of those hollow balls with edible nibbles in them, which fall out occasionally through strategically-placed holes, will keep Ben happily entertained for ages) or a change in routine, or gradual behavioural changes. But interestingly, in some instances Dodson treats his canine clients with drugs like prozac, & also – in the case of the Doberman mentioned here – a drug that’s been approved for treating human Alzheimers patients. Which seems to do the trick for this particular patient.
This recourse to pharmaceuticals isn’t a trial-&-error thing. Dodman originally got interested in this area after working with horses: apparently these animals can show a range of stereotyped behaviour that includes chewing on their stalls. Dodman & pharmacologist Louis Shuster hypothesised that this behaviour increased the production of endorphins in the horses’ brains – they could have been getting a natural pleasurable high. This hypothesis led to the obvious prediction – that treating the horses with drugs that block opioids would also stop the behaviour patterns, as the horses would no longer get that ‘high’ out of it. And treatment with opioid antagonists did indeed stop the chewing & other ‘stall vices’.
The opioid antagonists also block receptors for the neurotransmitter glutamate, which is involved in transmitting nerve impulses from one cell to the next & is the most common neurtransmitter in the brain. This led Dodman & Shuster to try other known glutamate receptor blockers on their compulsive animal patients, including the Alzheimers drug. This, combined with prozac, seemed to work on mice & dogs.
There’s a lot of serendipity in science. The animal results caught the attention of psychiatrists working with human OCD patients, given that some researchers think that glutamate signalling is involved in OCD. The same drug combination – albeit in a small trial of 44 patients (22 on standard treatment & 22 on the new combo) led to an improvement in those on the experimental treatment. So – there’s a piece of intellectual cross-fertilisation for you :-) (Mind you, the jury is still out on whether the underlying causes of OCD in humans & OCD-like behaviour in other animals is the same.)
Now that I come to think about it, Ben does have a thing about socks…
C.Holden & J.Travis (2010) Can dogs behaving badly suggest a new way to treat OCD? Science 329: 386-387