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Can a Dog Really Suffer From Depression?

Dogs and humans share similar psychological problems and treatments.

angela n photo-Creative Commons License
Source: angela n photo-Creative Commons License

Max seemed to be having a bad time over the past couple of weeks. He had lost his appetite, was not eating or drinking the way that he normally did and thus was losing weight quickly. He seemed to be lethargic, and spent a lot more time than usual sleeping. When he was awake he seemed nervous, edgy and common events seemed to worry him. None of the usual activities that normally made him happy seemed to interest him. Any psychologist seeing a person with Max’s symptoms would conclude that he was probably suffering from depression. The problem is that Max is not a person but is a German Shepherd Dog.

It was the late 1980s when Nicholas Dodman of the School of Veterinary Medicine at Tufts University was standing next to a colleague looking at a dog that had been brought into the Animal Behavior Clinic. The dog was showing symptoms similar to Max. Dr. Dodman received his veterinary training at the Veterinary School at Glasgow University in Scotland. His training was in veterinary surgery and anesthesiology. He was remarkably talented in the general field of veterinary medicine and at the age of 26, he became the youngest veterinary faculty member in Britain. He immigrated to the United States in 1981 and when he had settled in as a faculty member at Tufts University his interests began to change. He now began a specialization in the fields of animal behavior and behavioral pharmacology. He even went so far as to obtain an additional board certification in animal behavior from the American College of Veterinary Behaviorists. As he was learning more about behavior he began to see some of similarities between human psychological states and those which could be observed in dogs. Extrapolating from what he knew about human behavioral symptoms Dodman concluded that the dog he was examining that day was depressed and anxious. For a human with these symptoms the diagnosis would have been clinical depression, and so it seemed to him that this was also a reasonable diagnosis to suggest for the dog. His colleague shook his head warned him about the dangers of treating dogs as if they had such human-like feelings. His colleague argued “Dogs don’t experience the same mental states and emotions that people do.”

Dodman’s colleague was really restating one of the beliefs that many scientists have held since the 1600’s. It began with René Descartes, a French philosopher, mathematician and biologist who claimed that only humans have feelings and conscious mental processes. Animals were thought to be simply the equivalent of biological machines with no psychological processes worth mentioning. Two hundred years later Charles Darwin, whose theory of evolution changed our view of the biological world, reached a different conclusion. He suggested that the emotional experiences of animals are quite similar to those of humans. Over the past several decades research has been accumulating suggesting that Darwin was correct (click here for more on that).

Dodman was clearly siding with Darwin when he answered his colleague saying something on the order of “Look, the dog's brain is structurally similar to that of a human being. The biochemistry of a dog's nervous system works exactly the same as it does in humans. We now know that depression in humans is accompanied by chemical and hormonal changes. Here we have a dog who is showing the same kinds of symptoms which we might observe in a depressed person. Let me propose an experimental treatment. Let’s give the dog an antidepressant drug, the same kind that we use in people, and see what happens.”

What happened made history since the dog’s behavior improved dramatically.

Today most veterinarians are trained to accept that animals have emotions and can suffer from some of the same emotional problems that people do. This includes not only depression, but also anxiety, irrational fears and phobias, obsessive and compulsive behaviors and a broad range of neurotic and stress related problems. Currently there is a growing field of research called Animal Behavioral Pharmacology which has established that deficits in serotonin, a hormone that serves as a neurotransmitter in the brain, seem to play an important role in the control of depression in canines much the way that it does in humans. Because of this most veterinarians now use psychologically active drugs to control serotonin levels as well as other aspects of canine neurochemistry. Drugs for pets has become big business and the Pfizer Drug Company has established a companion animal division which brought in over a billion dollars last year.

How widespread such emotional conditions are in pets is difficult to determine. However Sainsbury’s Pet Insurance in the UK has been collecting some information. They suggest that depression and anxiety are widespread in the British canine population; the report indicated that 623,000 dogs and cats in the UK had suffered mentally in the previous year, while more than 900,000 suffered loss of appetite because of stress or emotional problems.

There is now a good deal of evidence which shows that the loss of a dog's owner or a companion dog can produce behavioral changes and symptoms which we would identify as that form of depression that we call "grief" if we saw it in a person (click here for more about that). Dogs are also sensitive to environmental conditions and changes, and the same way that moving to a new home in a new location can cause depression in children it appears that this can also affect dogs. Other things that can cause symptoms of depression include trauma from injury, disease, or abuse, being tied out on a tether or being socially isolated for long periods. Typical symptoms include a loss of interest in things that used to excite the dog, reduced activity, oversleeping, moping around and acting insecure, loss of appetite and sometimes changes in behavior such as increased irritability or more frequent household "accidents".

Taking the cue from Dodman's early work, when faced with depression in dogs veterinarians turned to the drugs designed for people. Just as Dodman had predicted, Prozac in various forms successfully controlled the depression and anxiety related problems in dogs. This prompted Eli Lilly, the pharmaceutical company that introduced Prozac, to create a chewable beef flavored version of the medication specifically designed for use by dogs.

However there are other solutions for depression in dogs that do not require the administration of pharmacological agents. Certain behavioral treatments (often modeled after treatments that are given to humans) can also combat depression. Increased exercise, which helps depressed people, also helps depressed dogs. Increased social interaction and play, and perhaps the addition of another dog to the family to provide continued or renewed social support and companionship can often improve the dog’s condition dramatically.

However you can also often avoid depression in your dog by taking care of yourself. Dogs have been bred to be empathic and responsive to human moods, and they may become depressed if their master is showing signs of melancholy (click here for more about that). Your dog is watching you — so if you are acting anxious and distressed the dog will interpret the state of the world based upon your behavior and conclude that there are things to worry about. That means that it is important to deal with your own low spirits first, and often the resulting change in your behavior may be enough to take care of your dog’s moodiness and depression.

Stanley Coren is the author of many books including: Gods, Ghosts and Black Dogs; The Wisdom of Dogs; Do Dogs Dream? Born to Bark; The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; Why We Love the Dogs We Do; What Do Dogs Know? The Intelligence of Dogs; Why Does My Dog Act That Way? Understanding Dogs for Dummies; Sleep Thieves; The Left-hander Syndrome

Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission

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