Ivermectin Poisoning in Cats

Although frightening, Ivermectin poisoning is definitely treatable and some cases are preventable. Toxicity stemming from sensitivity is impossible to predict in cats, but some cases stem from overdosing, which is prevented by double-checking the dose of home medication with the vet, and rigidly following directions. If your cat displays any symptoms of illness following an Ivermectin dose, she needs to see a vet immediately. The "wait and see" approach will only reduce the cat's chance of survival.

  1. Causes

    • Ivermectin poisoning occurs when the drug is administered either in too high of a dose or to a cat that has a predisposition toward sensitivity to the drug. Ivermectin is a popular anti-parasitic drug commonly used to treat heartworm infestations in dogs, but may also be used to treat ear mite infestations in cats. Occasionally, Ivermectin is applied topically into the ear canal to treat the mites directly, but is most often injected either subcutaneously or intramuscularly.

    Symptoms

    • Symptoms include tremors, vomiting or drooling, loss of appetite, inability to stand, blindness, seizure, or even death. Most of the time, symptoms occur within four to 12 hours of the dose, although it can sometimes take up to 96 hours for the first symptom to appear. Ivermectin reactions don't always happen with the first dose -- if the cat is on a daily treatment schedule, the reaction can happen at any time between the first and last dose.

    Treatment

    • When a cat is diagnosed with Ivermectin toxicity, the veterinarian will administer intravenous fluids with added electrolytes to help keep the body systems balanced, and to assist the elimination of the drug from the system. If the cat refuses to eat, tube feeding may be necessary, as it is important for cats to continue eating when critically ill to avoid putting additional stress on the liver. If the cat is having seizures, additional medications may be administered.

    Home Care

    • When the cat comes home from the vet, she will accompanied by any special instructions regarding her care for the remainder of her recovery period. Generally speaking, vets prefer that the cat remain somewhat confined for about a week, with rest encouraged and no strenuous activity. Sometimes a special bland diet is recommended, and feeding is done more frequently and in smaller quantities, especially if the cat has been tube fed.

    Frequency

    • Ivermectin sensitivity is very rare in cats, and most cases of toxicity arise from overdosing. When it is applied topically, Ivermectin does not enter the bloodstream, so poisoning is impossible, although localized reactions can occur. Toxicity occurs when the medication is injected into the cat, which is why vets may prefer the topical application for cats in delicate health, even though it may require a longer treatment period. Topical Ivermectin use is considered off-label.