Excessive hand washing, counting, clearing throat or blinking eyes. These behaviors, sometimes diagnosed as symptoms of obsessive-compulsive disorder (OCD) in humans, can also be found in dogs and other animals. Of course, a dog can’t wash their hands repeatedly, but they can lick their paws over and over again or suck on their flanks until they are raw.
For 20 years, veterinary behaviorist Nicholas Dodman and neurologist Edward Ginns have worked to prove a link between repetitive dog behaviors and compulsive human behaviors. They have since discovered the genetic pathways that determine the severity of canine compulsive disorder and believe their research on dogs will help humans with OCD as well.
According to the National Institute of Mental Health, OCD affects more than 2 million adults in the United States, or approximately 1.2 percent. And the World Health Organization ranks OCD among the 20 most disabling diseases for humans. Despite this, there is currently no cure for the disorder, and therapies – including cognitive behavioral therapy and medications – only benefit approximately. half of the patients looking for help.
In the genes
The research of Dodman and Ginns, published in the International Journal of Applied Research in Veterinary Medicine in 2016, is based on a decade of study of purebred Doberman Pinschers. They determined that “four genes – CDH2, a neural cadherin and three serotonin genes – modify the severity [of OCD]Says Dodman, professor emeritus at the Cummings School of Veterinary Medicine at Tufts University. Additionally, they found that structural brain abnormalities in dogs with canine compulsive disorder (CCD) were similar to those in humans with OCD.
This year, researchers in China reproduces their findings. Using different compulsions and a different race, Dodman says investigators “confirmed the involvement of the CDH2 gene” in the Belgian Malinois, which functions repetitively in a geometric pattern. But for Dodman, the icing on the cake is when a group of researchers in South Africa “Searched for the CDH2 gene in human OCD and found it to be involved. “
Dodman and Ginns believe that further research into CCD is the way forward to find a cure for human OCD. This is because dogs come naturally through their affliction (unlike laboratory animals, which are inflicted with disease for the sake of research). And their lack of genetic diversity within breeds allows a small study group of 100 bull terriers, for example, to obtain meaningful data, says Dodman. Similar studies on humans would require 10 to 20,000 people and cost millions of dollars, he adds.
Nature versus culture
But they don’t believe OCD can be explained by genetics alone. According to Ginns, professor of psychiatry at the University of Massachusetts School of Medicine, OCD is a complex trait clearly identified as being both genetically and environmentally influenced. Stress, in particular, “can affect cognitive and other brain functions. And we’re just starting to really appreciate that impact, ”he says.
On the one hand, OCD is not present in all human populations; New Guinea natives, for example, “don’t have compulsive anxiety disorders and fears for personal safety other than those they actually live with,” says Dodman. It is found, however, in millions of people in the “concrete jungle,” he adds, where there are flickering artificial lights, computer screens, lack of exercise and plenty of television. .
Read more: Is city life bad for your health?
Likewise, OCD is not found in the wild, but is rampant in zoos – from giraffes and elephants “weaving” or shaking their heads from side to side, to sea lions and polar bears “walking around. cycling in the water, ”says Dodman. “Anxiety stems from the fact that it arises from behaviors typical of their natural species. In other words, their coping mechanisms have gone awry.
Outside of zoos, horses, which spend 60 to 70 percent of their time in the wild pasture, will exhibit mouth-related compulsions when they cannot move freely. “[They] chewing on things, because they are not naturally nourished. They don’t graze all day. They put their food in the bag twice a day, ”says Dodman. “And they can’t walk anywhere because they’re in a 12- by 15-[foot] paralyze. ”Instead, they circle around, also known as stall.
Each dog has its own day
” When we are in a hurry, [these behaviors] get out of Pandora’s box under these conditions now defined by psychiatry. So each species does exactly what you want it to do, ”Dodman explains.
Dog compulsions run along breed lines. “These little groups, called breeds, are really helpful in finding genetics, pathways, to provide new treatments to people,” says Dodman. Long-haired dogs can demonstrate compulsive licking because they have to take care of their coat in real life, he adds. Likewise, bull terriers are hunters – they tend to circle around, chase items, and develop an obsession with items.
It took decades of research for the two researchers to convince the world that dogs and other animals also suffer from some form of OCD. “When we started talking about OCD and animals, there were disbelievers,” Dodman says. But now even those who had the most doubts are changing their minds. Dodman has now heard from colleagues who confessed to him that they “were starting to understand this story of animal OCD … It only took 20 years.”