Dogs and Serotonin


Depression, once a disease deemed too rare to merit study, has become so common that it is now a booming business. More and more people are asking: “When we stop at the pharmacy to pick up our Prozac, are we simply buying a drug? Or are we buying into a disease as well?” In the last 20 years depression numbers have rocketed and according to the World Health Organisation, more than 300 million people of all ages are suffering globally.

And it seems to be spreading to pets.

An article last week caught my attention — “Serotonin Syndrome in Dogs: Symptoms, Causes, & Treatment.” The article warns of the dangers of antidepressant-induced Serotonin Syndrome (SS), a condition that if left untreated, can result in “illness, altered mental states, and even death.” Considering I’ve seen first-hand the effects that antidepressants can have on humans, particularly depersonalization, aggression and suicidality, I have always wondered whether similar effects can be seen in canines. What might the growing practice of drugging our pets lead to?

An increased risk of antidepressant-induced ‘suicidality’ may be impossible to detect in animals, but it seems the deleterious effects of the drugs on us are similar in our canine companions. Symptoms of SS include confusion, depression, hyperactivity, lethargy, agitation, aggression and behavioral abnormalities. Bizarrely, it seems that vets are far more clued-in to the pharmacological effects on man’s best friend than doctors are.

Given the unashamed push to medicate the masses, whether sick or healthy (as illustrated by the widespread use of statins), the progression to animals is hardly surprising. With the human market arguably close to saturation, dogs are increasingly being diagnosed with many psychiatric disorders, such as anxiety, depression and ‘separation anxiety’. While some of this is down to neurotic owners, the pharmaceutical industry also has clear motives in targeting the pet market — the market is an extremely lucrative one, with a recent report by the Federal Trade Commission estimating that U.S. retail sales of pet medications are expected to grow to $10.2 billion by 2018.


Undoubtedly, dog owners do not set out to harm their beloved pets, yet when giving them psychotropic drugs, it is a distinct possibility. For instance, while benzodiazepines and tricyclic antidepressants are often prescribed to an ‘anxious’ canine, it seems far more likely that a vet will recommend an SSRI antidepressant (Selective Serotonin Reuptake Inhibitor).

Lilly’s SSRI fluoxetine (more widely known as Prozac) was approved for canine use by the FDA and repackaged for your doggie or moggy as ‘Reconcile’ for separation anxiety. Two other SSRIs, Paroxetine and Sertraline, although not approved for use in animals, are also prescribed by veterinarians for your dog’s woes. In the case of Reconcile, separation anxiety (dogs being left alone for lengthy periods) was the most common reason for prescribing in dogs, and in cats, inappropriate elimination (of urine).

Lilly’s own literature1 reports the following adverse reactions with dogs taking Reconcile/Prozac:

  • Calm/Lethargy/Depression – 32.9%
  • Shaking/Shivering/Tremor – 11.1%
  • Restlessness –  7.4%
  • Aggression –    4.2%

So, almost one in three dogs became depressed on Reconcile and an estimated 4 in 100 became aggressive. Furthermore, the reaction coded as ‘restlessness’ (at 7.4%) might sound innocuous but seems likely to be an indication of akathisia, a severe emotional state that often precipitates suicide in humans (see Dolin v GSK).

Considering that little Fido cannot verbalise a drug-induced effect, it seems bizarre that the American and European drug regulators (FDA & EMA) felt that the benefits outweighed the risks for dogs taking an SSRI. If we consider that so many humans have died or indeed, been maimed by SSRIs, is drugging your dog really the best option?

Would leaving a child at home alone for many hours justify prescribing them an antidepressant?

There are many mothers, fathers, siblings and spouses who are left bereaved because of an SSRI prescription — who now know what psychotropic drugs can do to the human psyche. It gives a whole new meaning to “I wouldn’t give this to my dog.”

Being Irish, though, one more thought occurs to me. The IRA would probably have had the English out of Ireland long ago if they bombed Crufts Dog Fair… perhaps Pharma are making a bigger mistake agitating our pets than they are agitating us.

Show 1 footnote

  1. Lilly. Reconcile PIL. In: FDA, editor. Online2007.


Mad in America hosts blogs by a diverse group of writers. These posts are designed to serve as a public forum for a discussion—broadly speaking—of psychiatry and its treatments. The opinions expressed are the writers’ own.


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  1. Oh dear…and if dogs become aggressive as a result of SSRIs (as many humans do), after attacking and maiming people, other animals, etc they will be labelled vicious and killed.

    Sad that we would be encouraged to do this to our beloved furry companions.

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  2. Well, dogs got protection from abuse before children – maybe if dog owners start getting upset about their doggie friends being screwed up by SSRIs, the idea will eventually translate into protecting children, and maybe someday even adults!

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  3. I was drugged at the time, it’s my only excuse.

    I had a half-feral kitten, and wanted to have a home where the kitties get along. But it wasn’t possible with this fearful cat. All the natural methods – catnip, Feliway, toys, feeding routines – didn’t work.

    Additionally, the other cat, a fairly well adjusted male, couldn’t figure out what the little cat was so afraid of, so he became a behaviour problem, too – spraying and dominating to compensate.

    So we put both of them on amitryptaline.

    It didn’t do much to the big fella, except make our life hell when we wanted to give him a pill. The little cat took the pills just fine – but she was only 6 months old – the time of her life when her brain is forming. She took the drugs for 6 months, which was when the big cat went to a new home (nobody would have this freaky little cat)

    She became apathetic, would not play (she was afraid to play before the drugs, so – at least she was calm about it now), was disengaged an non-interactive. She never got properly socialised.

    I don’t know how to measure IQ on cats, but I’ve had some pretty smart cats over the years. This cat isn’t quite “dumb as a box of rocks” – but she’s nowhere near a smart cat, either. Now that she’s 11 years old, she is more interactive and communicative than ever before – but I look at her, and see what the drugs have done to her, and regret regret regret it.

    It was part of what made me look at my own psych drugs, and wonder what happened to me. It made me angry at the people who put children and adolescents on these drugs, because those formative years are so important.

    My cat is still a stress-kitty, and will jump at her own shadow. But she’s undrugged now, and I am too. The vet was just trying to help what was an untenable situation. We changed the situation, and the drugs were no longer “needed.”

    It’s hard to apply this lesson to people – but maybe we should.

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    • We are too wimpy and afraid of ordinary pain now. If we don’t have permanent smiley faces 100% of the time we have a “disease.” Hurry up and break out the Zoloft!

      “Life is pain, Princess. Anyone who tells you otherwise is trying to sell you something.” ~The Princess Bride

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  4. Tranquilizers were always used in pets, not to treat an illness- vets are more honest than psychiatrists- they use them to tranquilize and they call them tranquilizers and not marketing names like anti psychotic, anti anxiety and anti depression meds.
    The use of ssri and psychiatric drugs to treat pets mental illness is concerning. Though I’m not sure how much the vets are buying into this. I’ve first heard about ssri for pets more than a decade ago, and most ppl still haven’t heard about it and find the idea hard to believe and ridiculous. So hopefully it’s not common practice and only a few misguided vets use these drugs on pets.

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  5. it is very popular here in Australia for cats and dogs – cat psychologists abound and behaviorists who will analyze your pet and prescribe. Cesar Milan with medication in his bag!!
    Outdoor cats its high risk as they become dopey and dull in their natural instincts .

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