Low platelet count after Moxidectin (ProHeart 6) in dogs

151 reports to the FDA describe low platelet count in dogs given Moxidectin. That is 0.3% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

151Reports

83%Marked serious

6.6%Recovered

21%Died or euthanised

5 daysTypical onset

How soon it started

Same day

36 26%

1–2 days

23 17%

3–7 days

21 15%

1–4 weeks

29 21%

Over a month

29 21%

How the animals did

Recovered

10 6.6%

Still unwell when reported

105 70%

Died

8 5.3%

Euthanised

24 16%

Not known

4 2.6%

Problems reported at the same time

73 48%

71 47%

64 42%

63 42%

61 40%

40 26%

35 23%

35 23%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

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 low platelet count in dogs?: 151 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 5 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).

Low platelet count with similar medicines

Low platelet count after Ivermectin + Pyrantel (Heartgard Plus) 137 reports · 0.1% of its reports
Low platelet count after Milbemycin Oxime + Spinosad (Trifexis) 159 reports · 0.1% of its reports
Low platelet count after Milbemycin Oxime + Praziquantel (Interceptor Plus) 75 reports · 0.2% of its reports
Low platelet count after Ivermectin (Heartgard) 31 reports · 0.3% of its reports

All reported side effects of Moxidectin in dogs · Medicines most reported with low platelet count