After the death of his long-time companion, Maxwell fell into a dark place. He no longer seem to take joy in life, refused to eat much, and lost a dangerous amount of weight—so much that his liver faltered. Following a stay in intensive care to stabilize him, Max was given antidepressants and this, combined with changes in the home environment, eventually drew him out of his deep depression.
Max is a cat. He’s also one of the many patients who appear in the pages of Pets on the Couch, the newest book by Nicholas Dodman, author of The Dog Who Loved Too Much. Dodman, founder of the Animal Behavior Clinic at Tufts University, shares the stories of a variety of animals (horses, parrots, cats, dogs) and argues that many of their psychiatric disorders have human analogues. Our pets have human qualities, he says, and recognizing this will allow us to help them better—and learn about ourselves. He answered questions from Mind Matters editor Gareth Cook.
How did you become interested in the psychological problems of animals?
In an earlier part of my career, some 40 years ago, I was a specialist veterinary anesthesiologist. Before anesthesia I could see that most patients were stressed (sometimes by the strange setting and whole process) and some were in pain. Ditto regarding the recovery period. I set about making the process less psychologically distressing for them, inventing (via appropriate medications) what I referred to as “the magic carpet ride.” With the aid of various cocktails of anti-anxiety drugs and analgesics, I arranged for our surgical patients to practically float into the induction room without a care in the world and recover similarly unphased. It was a rewarding experience to make animals feel so much more comfortable during a stressful time.
The event that brought about my conversion from anesthesiologist to behaviorist was one of those fortunate eureka moments while conducting a trial of morphine in horses along with my erudite side kick, Dr Louis Shuster, a pharmacologist. A happenstance observation of horses so treated was that they engaged in repetitive behaviors referred to as stereotypies. I knew that similar behaviors were exhibited by stalled horses that had not been given morphine. That led to a bright idea: how about giving a morphine antagonist to horses with the naturally-occurring stereotypies, know to equestrians as “stall vices.” Perhaps these behaviors were fueled by nature’s one morphine-like substances, endorphins. If so, a morphine antagonist, like naloxone (Narcan) should stop them in their tracks.
Long story short, it did and we were all converts into the brain-behavior connection. In my book I tell the story of the first horse we ever treated this way – a palomino called Pokers Queen Bee. A compulsive “stereotyper” who constantly anchored her large incisor teeth onto the stall door and leaned back, grunting as she went, Poker’s behavior stopped as soon as the Narcan was injected. That experiment made three converts: the horse owner quit her job as highly paid executive in Boston to do a PhD in biochemistry and Loyola University in Chicago; Dr. Shuster changed his research focus from studying drugs of addiction to behaviors of addiction; and I switched from anesthesiologist to a person consumed by an interest in behavior (in what makes animals tick).
What is the evidence that animals suffer the same kinds of psychological problems as humans? Why do you think this is a useful analogy?
Veterinary behaviorists acknowledge a plethora of behavior problems that plague animals. They treat aggression, anxiety-based conditions, excessive fears and phobias, compulsive behaviors (like Poker’s stall biting), and more recently even post-traumatic stress. Reference to the Diagnostic and Statistical Manual of Psychiatry (DSM) – the diagnostic bible for psychiatrists – confirms that humans suffer from similar conditions. In fact, there is much we veterinary behaviorists see that does not have a compelling counterpart in the DSM.
Some argue that the “mental” (behavioral) conditions animals suffer from may look like the human conditions but that’s where the similarity ends. But in my book, I discuss the fact that isn’t where the similarity ends. We have found a gene that predisposes a dog breed – Doberman pinscher—to a canine form of compulsive behavior (Blanket and flank sucking). Glitches in that gene have subsequently been confirmed to be involved in conferring susceptibility to obsessive-compulsive behavior (OCD) in humans. Sophisticated imaging studies have confirmed that the brains of affected Dobermans show changes that are similar to those found in people with OCD. We also came up with a novel treatment for compulsive behavior in animals and found that the same treatment works well in human sufferers.
That treatment was with drugs that block the excitatory neurotransmitter glutamate at NMDA receptors (which our newly discovered gene is instrumental in forming). We made that discovery because certain “right handed” (dextrorotary) versions of opioid blockers that shouldn’t block opioid systems reduced the frequency of repetitive behaviors in animals. That didn’t make sense to us. So where were these drugs acting? “On NMDA receptors” was the only solution we could come up with because all varieties of opioid blockers work there. So we tried right-handed versions of opioid agonists (d-methadone) and antagonists (d-naloxone) as well as ketamine, a known NMDA antagonist in an equine model. All of the drugs worked. This led to a Tufts patent that, to this day, has yet to garner the interest big Pharma. But that did not stop us from publishing a study showing that human OCD sufferers benefit from a glutamate blocking drug, memantine. Memantine is still in use today – off label – to treat OCD in humans and animals.
Tell me about your experiences with “war dogs.”
I identified post-traumatic behavioral changes in dogs years ago. My first subject, described in the book, was a dog that had been shot by a Boston policeman. Following this ns ear death event, the dog became hypervigilant, terrified of anything to do with the police (police cars, sirens, men in police uniform) and would shake and shiver and avoid them like the plague. He was brought to me because of his nighttime issues, difficulty sleeping and nightmarish acting out at night.
Fast forward to Gina, a dog whose job it was to enter terrorist strongholds after a “flash bang” grenade had been tossed in. Imagine the blinding flash, the noise, the shouting and confusion. On coming home, Gina showed signs and of PTSD and her story made it to the national press. I have seen many cases of PTSD in my clinical practice – not the trauma of war but other terrifying and traumatic experiences. Slowly but surely, the army came round to recognizing PTSD in dogs of war. It is now called Canine PTSD or cPTSD. Not all dogs of war are susceptible to it, only about 5-10 percent. Yet not all soldiers are susceptible to PTSD. Our treatment of cPTSD is with mood stabilizers, like Prozac, and drugs that block the action of adrenaline-type neurotransmitters, like clonidine, and some dogs show acceptable or even good improvement. Some veterans with PTSD are treated along the same lines, using mood stabilizers and anti-adrenaline drugs.
How do you see OCD at work in animals?
All veterinary behaviorists see compulsive behaviors in their caseload on a regular basis. Purist decline to call it “obsessive” because you can’t access animal’s thoughts so obsessions are difficult if not impossible to verify. So canine versions are referred to a Canine Compulsive Disorder (CCD); the feline version is FCD, and so on across the species. A classical canine compulsive disorder is acral lick, which I describe in detail in the book. Not only does it look like a human OCD (handwashing) but it responds to treatment with medications in the same way and over the same time course as the human condition. Now that the genetics underlying compulsive disorders in humans and animals (dogs at least) are falling into place and brain imaging studies take the parallels even further, it is getting harder to stick to the “human exceptionalism” explanation for psychiatric disease—and easier to accept the fact that we are all mammals on this planet together. It’s hardly surprising that we are so similar given the fact that we share virtually the same DNA and have more than half of our genes in common. More and more, the “One Medicine” approach to treating biological systems, human or animal is paying off in the things we can learn about animals from studying humans, and vice versa.
What are the questions in animal psychiatry that you are most excited to explore next?
The next steps in animal psychiatry are to identify genes and pathways involved in a plethora of humanesque behavioral issues. For example, I have just read about the discovery of canine genes involved in anxiety and stress. I assume human researchers will jump right on this to check if the same genes are involved in anxiety disorders in people. Once the genes are known, the downstream pathways can be identified and new points of therapeutic intervention can be devised. This way, each and every human psychiatric condition with an animal equivalent can be studied in spontaneously occurring veterinary equivalents. It is a win-win for animals and people to proceed in this way and is much it is a much more productive way to search for genes in, say, dog breeds, which are closed populations, than in the outbred human population. The needle is the same size but the haystack is smaller.