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Labrador Retriever survives rare serotonin syndrome


Mav, a nine-year-old Labrador Retriever, was diagnosed with serotonin syndrome after ingesting up to 600 dietary sleep supplement pills.

Mav (Image courtesy of Pet Poison Hotline)

Mav (Image courtesy of Pet Poison Hotline)

Mike Axthlem of Minneapolis, Minnesota, arrived home one day to find his dog Mav acting guilty and he defecated in the house, which was unlike him, according to Axthelm. Once Mav began foaming at the mouth and the family discovered an empty dietary sleep supplement pill bottle, they immediately rushed him to the emergency room.

After Axthelm called the veterinary hospital ahead of time, Amy Stockton, DVM, instructed him to call the toxicology experts at Pet Poison Helpline who determined Mav ingested a severely toxic volume of 5-HTP. 5-HTP is a compound that helps raise serotonin levels in the brain, and too much can cause GI signs, CNS stimulation, and serotonin syndrome.

By the time they arrived at the hospital, Mav was blind, unconscious, and had been having seizures for 15 minutes. His pupils were dilated and unresponsive, frothy foam was coming out of his nostrils, and fetid stool was running out of his rectum.

The hospital staff learned that Mav ingested around 600 dietary sleep supplements. This led his veterinarian to witness her first case of serotonin syndrome, a rare and potentially deadly condition.

“This was my first case of serotonin syndrome in my 25 years of practice,” Amy Stockton, DVM, explained in an organizational release. “We started with injectable Keppra, which did absolutely nothing for him, so we gave him an additional dose.”

“Still shaking, he received my entire supply of methocarbamol IV. That didn’t help much, so we crushed up tablets and gave [them] rectally. We then administered phenobarbital and crushed up his cyproheptadine dose and administered that rectally," she continued.

Mav’s temperature when he arrived at the hospital was 105.5 °F, which veterinary professionals reduced with cold fluids, and his blood pressure remained normal. Clinicians administered 3 doses of cyproheptadine 4 hours apart to manage the serotonin syndrome. His pupils became less dilated and more responsive to light within 4 hours, and by 8 hours, he was conscious and responsive. Twelve hours after the ordeal began, he was still weak but able to go outside.

With the help of Pet Poison Helpline, Dr Stockon and her team successfully treated Mav, who has made a full recovery.


Probing Pooch Treated for Serotonin Syndrome After Eating 600 Sleep Supplements. News release. Pet Poison Helpline. January 17, 2022.

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