Fever after Ivermectin (Heartgard) in horses
The FDA has received 34 reports of fever in horses after Ivermectin. That is 4.9% of all reports for this medicine, compared with 4.8% across reports for all horse medicines.
34Reports
5.9%Marked serious
2.9%Recovered
18%Died or euthanised
–Typical onset
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How the animals did
Problems reported at the same time
Age of the animals
About this medicine
Ivermectin prevents heartworm disease (monthly).
Products with this ingredient include Heartgard. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.
Some herding breeds (for example Collies) carry the MDR1 gene variant and can be more sensitive to this drug class at high doses.
Questions owners ask
- Can Ivermectin cause fever in horses?
- 34 reports link the two, but a report alone does not prove the medicine was the cause: other illnesses, other medicines or coincidence can be involved. Your vet can judge it for your animal.
- What should I do?
- Don't give another dose until you've spoken to your vet, and keep the packaging so you can tell them the product and dose. Your vet can also report it to the FDA (or you can, through the manufacturer or FDA form 1932a).
Fever with similar medicines
- Fever after Ivermectin + Praziquantel 46 reports · 1.7% of its reports
- Fever after Moxidectin (ProHeart 6) 57 reports · 4.2% of its reports
- Fever after Moxidectin + Praziquantel 29 reports · 7.8% of its reports
All reported side effects of Ivermectin in horses · Medicines most reported with fever