Serotonin Syndrome In Dogs: Symptoms, Causes, & Treatments

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Serotonin syndrome in dogs is a potentially life-threatening condition caused by an increase of serotonin in the body from exposure to antidepressant medication. Serotonin is an important neurotransmitter in a dog’s brain that regulates heart and lung function, behavior, awareness of pain, appetite, body temperature, and movement. When used appropriately, antidepressants elevate the levels of serotonin in the brain. However, there are several situations where an antidepressant might be mixed with other medications, react with certain foods, or be poorly tolerated by a dog and lead to serotonin syndrome. This can cause illness, altered mental states, and even death if it goes untreated. If your dog is showing signs of serotonin syndrome after taking an antidepressant, consult your veterinarian right away. Treatment must begin quickly, or the condition may be fatal. Here is what you should know about the symptoms, causes, and treatments for serotonin syndrome in dogs.

Symptoms Of Serotonin Syndrome In Dogs

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Serotonin syndrome in dogs can cause symptoms throughout the body because serotonin is so integral in regulating much of the body’s functions. It can affect the cardiovascular system, the nervous system, the gastrointestinal tract, metabolism, and the respiratory system. Symptoms tend to come rapidly, within 10 minutes to 4 hours of taking medication. If you see the following symptoms in your dog after they have been exposed to antidepressant medication, contact your veterinarian immediately.

  • Vomiting
  • Diarrhea
  • Tachycardia (rapid heart rate)
  • Rapid breathing
  • Increased body temperature
  • High blood pressure
  • Trembling
  • Seizures
  • Difficulty walking
  • Rigid muscles
  • Confusion, depression, hyperactivity
  • Lethargy
  • Agitation or aggression
  • Behavioral abnormalities
  • Temporary blindness
  • Coma

Causes of Serotonin Syndrome In Dogs

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Exposure to antidepressant drugs causes serotonin syndrome in some dogs. Some of the most common antidepressants prescribed to dogs are busiprone, fluoxetine, and clomipramine. When used correctly, these medications usually work properly. However, there are some circumstances where the drugs create an excess of serotonin, and serotonin syndrome is the result. Here are some reasons these drugs might result in serotonin syndrome.

  • Dosage is too high
  • Other drugs that affect serotonin are taken (such as amphetamines, fentanyl, or lithium)
  • The dog is particularly sensitive to drugs that affect serotonin
  • Certain foods interact with the medication, such as cheese, turkey, red meat, bananas, peanut butter, or anything containing L-tryptophan)

Treatments For Serotonin Syndrome In Dogs

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Treatment for serotonin syndrome in dogs needs to begin quickly, or the condition may be fatal. If the condition is caught within a half hour, activated charcoal can be ingested to reduce the amount of antidepressant that the dog’s system will absorb. If the drug is still in the stomach, inducing vomiting or stomach pumping may be an option. Sometimes oxygen therapy or intubation may be administered. Medication may be prescribed to control seizures or tremors, and a serotonin antagonist will be given.

Use of the medication that caused the serotonin syndrome should be discontinued, as should consumption of any foods or other drugs that affect serotonin. Once the dog recovers, a veterinarian will determine if prohibited foods can be reintroduced to the diet.

Prevention goes a long way. Follow all instructions from your veterinarian when giving your dog antidepressants, and make sure they are aware of any other medications, even over-the-counter drugs, that your dog is taking.