The chaos of compulsion
Doberman pinschers: highly intelligent, energetic, sweet and affectionate. Not many would believe that owning this friendly breed of dog could become a nightmare—that is, until the animal develops canine compulsive disorder (CCD). This condition includes behaviors like spinning, tail chasing, fly biting, licking, hoarding, biting or sucking, and it usually results in self-inflicted pain for the dog.
Now researchers, human doctors and veterinary professionals are helping animals afflicted with these problems thanks to a new field of research dedicated to compulsive disorders. All it takes is a close eye and the patience to find answers.
For Nicholas Dodman, BVMS, DVA, DACVA, DACVB, professor emeritus at Tufts University and the Cummings School of Veterinary Medicine, it started in the 1980s while he was researching cribbing, or compulsive biting, in horses. He quickly came to learn that using an opioid blocker—for example, he initially used naloxone—would help horses completely stop the behavior. “That was a pretty epic find,” Dr. Dodman tells dvm360.
After publication of The Boy Who Couldn’t Stop Washing, which popularized the research of Judith Rapaport, MD, on obsessive compulsive disorder (OCD) in humans, Dr. Dodman turned his attention to other species in need of help with their compulsions—namely, things like acral lick granuloma in dogs.
“Dr. Rapaport treated acral licking as you would treat human OCD and found that these dogs responded as humans did,” Dr. Dodman explains. “So the research had face validity and predictive validity, though the construct between humans and dogs wasn’t quite there. But still, that opened the veterinary field to start considering these tics that weren’t researched or looked into as compulsive disorders.”
Canine compulsive disorder cannot be called “obsessive,” Dr. Dodman says, because there’s no scientific evidence proving that animals obsess like humans. Still, Dr. Dodman and those researching with him went as far as they could by doing an imaging study. “We took a bunch of Doberman pinschers, half with acral lick and half without, and MRI-scanned them with the help of the head of MRI at McLean Hospital, an affiliate of Harvard Medical School.”
What Dr. Dodman found changed the game. “When we scanned the Dobermans with acral licking, we found they had sophisticated, minute details in the brain that are also found in humans suffering from OCD,” he says. “The changes were, if not identical, compellingly similar.”
Along with MRI tests, Dr. Dodman also looked at genetics. “Again,” Dr. Dodman says, “we chose Doberman pinschers and found a gene called CDH2, otherwise known as neural cadherin (NCAD), expressed most significantly in dogs with the compulsive problem.” His research was confirmed in peer-reviewed medical journals. And later, psychiatrists in South Africa discovered that the same deformation of CDH2 was found in humans with OCD.
“Older generations typically believe what they were taught,” Dr. Dodman explains. “And they were taught that dogs just lick a lot—that it’s just a thing dogs do. And then they’re told to put them on steroids and antibiotics and hope it stops. But it doesn’t stop.”
— Dr. Nicholas Dodman
These findings are still widely discussed and debated, however. According to Dr. Dodman, that’s because OCD and CCD look different to most observers. “Dogs would never count compulsively like a human with OCD might,” Dr. Dodman says. “But dogs do hoard, and both conditions are linked to anxiety. Anyone that knows the literature knows that it’s the same—humans have OCD, dogs have CCD, cats have feline compulsive disorder (FCD). We’re looking at feline genetics as we speak, and horses sometime in the future when we have more to go off of.”
If many of the signs and symptoms are the same for humans and canines, is the treatment the same as well? Dr. Dodman gives a resounding yes. “When tested in mice, blocking glutamate worked,” he says. “It worked in dogs and horses as well. That’s when we went to Harvard and requested permission from Dr. Michael Jenike, the founder of the Obsessive Compulsive Disorder Institute, to test it out on human patients using memantine.”
The result? Dr. Dodman says it was “miraculous”—or, at least, the human patients tested used the very word. “Talking to Dr. Jenike today, he says hundreds of his patients are still on that treatment plan,” Dr. Dodman says. “He was very skeptical at first, but by the end he knew that our veterinary science was onto something big.”
Even after winning the belief of human doctors, though, Dr. Dodman is aware that skepticism still brews in the world of veterinary medicine. “Older generations typically believe what they were taught,” Dr. Dodman explains. “And they were taught that dogs just lick a lot—that it’s just a thing dogs do. And then they’re told to put them on steroids and antibiotics and hope it stops. But it doesn’t stop.”
Dr. Dodman acknowledges that there are distinctions between CCD and other licking-related problems. “Not all licking is compulsive,” he says. “You have to differentiate. If they’re licking between their toes it could be pyoderma. If they’re licking their limb, the location can be pretty conclusive of CCD. The difference is that CCD is a problem that starts in the head, not on the skin.”
And Dr. Dodman’s advice for veterinary professionals when it comes to compulsive disorders? “The moment it dawns on you that it could be CCD, start treatment rather than wait for it to get worse,” he says. “I’ve treated sores that veterinarians have looked over, and even when the animal is better after treatment there are still scars and other injuries.”
Dr. Dodman also emphasizes the value of a second opinion. “If whatever you’re doing doesn’t seem to be helping, get a second opinion,” he says. “Teaching hospitals are really helpful for this sort of thing, as are board-certified dermatologists.”
With new strides being made in research every day, animals, pet owners and humans suffering from compulsive disorders can rest a bit easier knowing that there’s hope for their problems as the veterinary world breaks barriers in scientific research.