Swelling after Moxidectin (ProHeart 6) in horses

The FDA has received 83 reports of swelling in horses after Moxidectin. That is 6.1% of all reports for this medicine, compared with 19% across reports for all horse medicines, so it is reported less often than average with this medicine.

83Reports
3.6%Marked serious
2.4%Recovered
9.6%Died or euthanised
–Typical onset
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How the animals did

Recovered
2 2.4%
Still unwell when reported
3 3.6%
Died
7 8.4%
Euthanised
1 1.2%
Not known
70 84%

Problems reported at the same time

Age of the animals

Under 1 year
10
1–3 years
15
4–7 years
16
8–11 years
15
12+ years
12

About this medicine

Moxidectin prevents heartworm disease (monthly topical, or a 6- or 12-month injection for dogs).

Products with this ingredient include ProHeart 6, ProHeart 12. 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 Moxidectin cause swelling in horses?
83 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).

Swelling with similar medicines

All reported side effects of Moxidectin in horses · Medicines most reported with swelling