Haemoconcentration after Moxidectin (ProHeart 6) in dogs

The FDA has received 37 reports of haemoconcentration 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.

37Reports
81%Marked serious
27%Recovered
11%Died or euthanised
Same dayTypical onset
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How soon it started

Same day
21 57%
1–2 days
8 22%
3–7 days
6 16%
1–4 weeks
0 0.0%
Over a month
2 5.4%

How the animals did

Recovered
10 27%
Still unwell when reported
22 59%
Died
2 5.4%
Euthanised
2 5.4%
Not known
1 2.7%

Problems reported at the same time

Age of the animals

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

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 haemoconcentration in dogs?
37 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 the same day 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).

Haemoconcentration with similar medicines

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