In this VETgirl online veterinary continuing education blog, we review ivermectin toxicity in a cat. In this video, a 10-year-old, male neutered, Domestic Long Hair presented to the emergency services for ivermectin toxicity. The owner had given this cat an equine dewormer containing ivermectin 1.87% and praziquantel 14.03%. The equine dewormer syringe contained 120.1 mg ivermectin and 897.6 mg of praziquantel. The owner administered 1/4 teaspoon in cat food to share between all 5 cats; however, it was estimated that this particular cat ingested 40-50% of the food; this made potential ingestion (worst case scenario of the whole amount ingested) of approximately 3 mg/kg of ivermectin. Previously, the owner had dewormed her cats this way in the past without any complications. This was dosed earlier in the day, and the cat developed ataxia and an inappropriate mentation with several hours. The ASPCA Animal Poison Control Center was consulted for life-saving advice.

While the active ingredient, praziquantel, was not of concern, the ivermectin dose was consistent with the development of clinical signs of ivermectin toxicosis. While most cats handle high-dose ivermectin well, clinical signs can be seen in normal healthy cats above 2.5 mg/kg. Clinical signs of ataxia, mydriasis, and vomiting can be seen, while at higher doses > 5 mg/kg, tremors, blindness, seizures, respiratory failure, and coma can be seen.

On presentation, the cat was obtunded, recumbent, had intermittent muscle tremors, and lacked a menace bilaterally. A normal direct and consensual pupillary light response was present bilaterally. Upon IV catheter placement, the cat became agitated, so butorphanol (at 0.3 mg/kg IV) was administered.

As ivermectin is considered lipophilic, a trial of intravenous lipid emulsion (ILE) was administered to create a “lipid sink.” A 20% ILE solution was dosed at 1.5 mL/kg over 3 minutes, then at 0.5mL/kg/hr ILE for 30 minutes. As there was no signs of clinical improvement, an additional dose of ILE was repeated several hours later. While ILE isn’t meant to be the end-all, be-all antidote for fat-soluble toxins, it can often be effective in treating patients with ivermectin toxicosis. Unfortunately, no dramatic improvement in clinical signs was seen with the ILE; however, with supportive care, the cat was discharged 72 hours-post ingestion with mild persistent ataxia.

When in doubt, call the ASPCA Animal Poison Control Center for life-saving advice 24/7 with any poisoning situation. For more life-saving advice, check out VETgirl’s other videos.

  1. Hello, vetgirl
    Injected my 4months cat with ivemectin 1% 2mls and after it started working but it goes on falling down and this is the 3rd day
    Now was it over dose if so what should l do to correct the problem?
    Kind regards
    Moses Uganda (East Africa)

    • Sounds like a significant overdose, as most 4 month old cats are 4 pounds (1.8 kgs), and it sounds like you gave 1% (10 mg/ml) X 2 mls = 20 mg. 20 mg/1.8 kgs = an 11 mg/kg overdose. I’d get to a veterinarian as there’s nothing you can do at home – I would stop administering it asap.

  2. Qual seria a dosagem indicada de ivermectina veterinária para um gato de adulto de 5.800kg com sarna ? Comprei ivermectina de 1mg cada comprimido a bula manda dar 1 cp por semana, será que essa dosagem fará mal?

  3. My one and a half year old cat (weighing 4.5-5kg) was suffering from a huge maggot wound in the leg. There’s no veterinary service in locality so we were unable to get him any professional help. We gave him a 10 mg tablet of Ivermectin with food. Unfortunately, after 4 hrs he was unstable while walking, and then was found lying at our backyard with heart beat going on, it’s been an hour since he’s like this, can anyone please help me with the situation and let me know if recovery is possible or not?

    • He sounds really sick and ill and needs medical attention. He could be weak from sepsis/infection in the leg versus the ivermectin. He needs the wound flushed, fluids to hydrate him, deworming, antibiotics, nursing care and more. Please try to find a veterinarian or medical attention if possible.

  4. Le puse a mi dos gatas nopucid, ivermectina al 0.5 % pesan 4.5 y 3.8 cada una dos años tienen. Le puse a cada en su pelaje 2.5 ml le dejé 10
    Minutos y las bañé pero solo con agua al otro día la más delgada empezó con síntomas de q chocaba todo y pupilas dilatadas la lleve al veterinario mediodía para la noche no mejoraba y ahora quedaron Internadas las dos. La más flaquita estaba muy mal y la otra no tanto pero igual la interné. Ayuda necesito saber si se va a salvar

  5. Hi. This is my experience with my 4-month-old kitten. If your cat or kitten has ivermectin overdose, take them to the vet IMMEDIATELY if you can. It CAN BE TREATED regardless of what some of the articles you see online say. If you cannot reach a vet, here’s what I did. I managed to call a vet after making countless calls and he told me to feed my cat 100 plus ACTIVE (or normal 100 plus but SHAKE THE BOTTLE AND GET ALL THE GAS OUT) (if you don’t have that where you are, call a local vet and ask what you can get; maybe an isotonic drink, shake all the gas out and maybe dilute it with water) (or coconut water); this helps to flush out the medicine – we gave around 2-5 ml every hour. If you are trying this, make sure not to overfeed and monitor closely the amount you’re feeding. There was improvement. We did have to force feed sometimes as she wouldn’t just drink it but it was so worth it (fed her while she was in an upright position so she wouldn’t choke – use a small syringe if you have one). We also fed her some water. She peed a lot after about an hour or so and that was a good sign. We continued feeding her the 100 plus overnight till we could go to the vet. In the morning, took her immediately to the vet (pls state to your vet that it is an emergency and your cat had an overdose or toxicosis so they will attend to it as soon as possible even if there are other patients – very important to see the vet QUICKLY). Our vet examined her and said it was possible to recover and asked us to give her coconut water (about 2 ml every hour) and prescribed some other meds to give her energy. Within a few days to a week, she was doing much better. With God’s grace, she is a healthy cat now, no symptoms and back to normal. She even regained her sight. So glad that the vet that night picked up and told me what to do. So glad the vet the next morning did what she could to save my cat. She had bad symptoms a few hours after taking the medicine. Blindness, wobbly when walking, bumping into furniture, she was scared of us too. We had to calm her down slowly and let her know it was us as she couldn’t see. It was a very scary experience but I’m so grateful that she’s okay now. I hope this helps someone and don’t lose faith. That’s what we named her. Love and light

    Pls see the vet ASAP and if you have any questions, feel free to comment here. Do not take this as an experts’ advice or replacement to see the vet. This is only my experience and is in no way meant to replace professional consultation and advice.

Leave a Reply

Your email address will not be published.