Exercise intolerance after Moxidectin (ProHeart 6) in dogs

The FDA has received 31 reports of exercise intolerance in dogs after Moxidectin. That is 0.1% of all reports for this medicine, compared with 0.0% across reports for all dog medicines, so it is reported unusually often with this medicine.

31Reports
19%Marked serious
3.2%Recovered
9.7%Died or euthanised
37 daysTypical onset
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How soon it started

Same day
3 30%
1–2 days
1 10%
3–7 days
1 10%
1–4 weeks
0 0.0%
Over a month
5 50%

How the animals did

Recovered
1 3.2%
Still unwell when reported
6 19%
Died
2 6.5%
Euthanised
1 3.2%
Not known
21 68%

Problems reported at the same time

Age of the animals

Under 1 year
1
1–3 years
14
4–7 years
7
8–11 years
8
12+ years
0

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 exercise intolerance in dogs?
31 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.
How soon after a dose was it reported?
In half of the reports with dates, it started within 37 days of the first dose.
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).

Exercise intolerance with similar medicines

All reported side effects of Moxidectin in dogs · Medicines most reported with exercise intolerance