No sign after Ivermectin (Heartgard) in horses

47 reports to the FDA describe no sign in horses given Ivermectin. That is 6.8% of all reports for this medicine, compared with 2.8% across reports for all horse medicines, so it is reported unusually often with this medicine.

47Reports

0.0%Marked serious

11%Recovered

0.0%Died or euthanised

–Typical onset

How the animals did

Recovered

5 11%

Still unwell when reported

1 2.1%

Not known

41 87%

Problems reported at the same time

Accidental exposure

22 47%

Locking mechanism abnormal

9 19%

Overdose

6 13%

Dispenser, abnormal

1 2.1%

Swelling

1 2.1%

Lethargy

1 2.1%

Lameness

1 2.1%

Walking difficulty

1 2.1%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

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 no sign in horses?: 47 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).

No sign with similar medicines

No sign after Moxidectin (ProHeart 6) 204 reports · 15% of its reports

All reported side effects of Ivermectin in horses · Medicines most reported with no sign