Bipolar Disorder in a Dog

By Rebecca Bragg

The question of whether dogs have human-like emotions and suffer from many of the same mental illnesses is no longer controversial in mainstream veterinary medicine. Now, vets agree that they do and often prescribe the same kinds of drugs for troubled dogs that doctors prescribe for human patients to ease similar symptoms. As of 2014, no diagnostic term equivalent to bipolar disorder in humans exists for dogs -- but that might soon change. Researchers in an ongoing European study into the genetics of major neuropsychiatric illness strongly suspect that this complex human disorder affects dogs too.

Bipolar vs. Other Mental Disorders

Research has established that dogs suffer from emotional and mental disorders similar to those that bedevil people, including anxiety, phobias and the canine equivalent of obsessive-compulsive disorder. Whereas people with OCD may, for instance, wash their hands obsessively, dogs display symptoms such as repetitive tail-chasing and flank-chewing. In both species, the same types of drugs help to relieve symptoms. Human bipolar disorder, on the other hand, is a much subtler and more complex condition believed to involve interplay among genes, environmental influences and brain chemicals. In people with bipolar disorder, characterized by extreme mood swings between euphoria and despair, the nature of thought patterns and processes plays an important diagnostic role. But the obstacle to clear parallels in dogs is that no matter how well we believe we know our furry friends, they can't tell us what they're thinking.

The Conundrum of "Cocker Rage"

A bizarre -- and fortunately, uncommon -- phenomenon that seems mainly to affect English cocker and springer spaniels is playing a key role in determining whether dogs can suffer from bipolar disorder. Dogs may display inappropriate aggression for many reasons not immediately obvious to humans. When that happens, their owners need expert help to find out what's bothering their pets and fix the problem before somebody gets hurt. But "cocker rage" leaves the experts scratching their heads. Without warning or provocation, otherwise friendly dogs fly into fits of rage so uncontrollable that they often attack and bite their owners. After these episodes pass, the dogs, appearing to be ashamed of what they've done, return to being their normal, friendly selves. A survey of Norwegian vets revealed that because of this, English cockers were 10 times more likely to be euthanized for aggression than other breeds.

The Lupa Project: An International Collaboration

The number of studies exploring dog genetics in an effort to cast light on human disorders exploded after scientists finished decoding the canine genome in 2005. In January 2008, the Lupa initiative, a collaborative project encompassing 20 schools of veterinary medicine from 12 European countries, began its research. Lupa's mandate is to study dogs afflicted with confirmed or suspected human-like disorders in hopes of identifying genetic markers shared by people. Purebred dogs are easier to study because their genomes are more uniform and thus simpler to compare than those of humans, Lupa explains. Methodology involves collecting DNA samples from dogs with various afflictions and comparing these with the DNA of healthy dogs of the same breed.

Bipolar Disorder and Cocker Rage

A Lupa study into the genetic profiles of canine disorders that appear to have counterparts in human neuropsychiatric disorders, including schizophrenia and bipolar disorder, is being led by the Norwegian School of Veterinary Sciences in Oslo. Since inappropriate aggression is a feature often seen in people with these conditions, the Norwegian researchers believe that the phenomenon of cocker rage might hold the key to fitting pieces of the puzzle together. To that end, they're comparing the genetic composition of even-tempered and enraged English cockers to identify the location of the defective genes that researchers feel certain must be there. The specificity of cocker rage, not only to that breed but also to family clusters within it, "leaves no doubt about the strong inherited component underlying this trait,” the Norwegian investigators say.