UF veterinarians save dog that ingested horse medicine

A dog that barely survived after treatment at the University of Florida Small Animal Hospital for acute ivermectin toxicity went home with his owner recently, prompting UF veterinarians to warn pet owners to take stock of all their pets’ medications, particularly how and when they are administered, especially around other animals in the household.

“Many people already know to be aware of medications in their homes, and to be careful how those drugs are stored so that pets and children can’t get access to them,” said Dr. Carsten Bandt, an emergency and critical care specialist and chief of the hospital’s emergency service. “However, people may not think about environments other than houses, such as barns or farms, where different types of animals frequently mingle and medications may be given outside.”

Sandra Johnson, who has a farm in Archer, gave her four horses their deworming medication on May 17 but didn’t see her 2.5-year-old Australian shepherd, Charly, creep through the barn. When she did see him a few minutes later, Charly’s head was down, and soon after, he was crawling. Johnson knew immediately that her dog’s situation was an emergency, but didn’t realize what had happened until a veterinarian asked if Charly had consumed ivermectin.

It turned out the medication she had given her horses, unlike the type she usually purchased, had been flavored, and Charly had eaten what one of the horses spit out. Flavoring in medications may make dosing easier, but it also makes lost doses more enticing to animals not suited for the treatment.

“It’s when you deviate from your routine that things start to fall apart,” Johnson said. “If something smells good, a dog is going to eat it.”

Ivermectin is routinely used to prevent heartworm and to treat ear mites in many pets. The drug is also used as a general dewormer in horses.

”In most cases and in most breeds of pets, side effects are not a concern with conventional doses,” Bandt said. “However, in Charly’s case, not only did he consume an extremely powerful dose, since the medication he ate was intended for a horse, but on top of that, Australian shepherds have a genetic sensitivity to ivermectin that allows the drug to enter the central nervous system.”

Acute ivermectin toxicity paralyzed Charly, who was first treated with lipid infusion and had to be placed on a ventilator to help him breathe. On May 26, UF veterinarians disconnected the ventilator and Charly went home with his owner on June 1.

He returned to UF because of a small skin infection, but continues to do well, veterinarians said.

“His infection was a side effect of laying down for such a long time, but otherwise he is doing great,” Bandt said. “He is running around at home, playing with his littermate and trying to chase the horses.”