Leucopenia after Moxidectin (ProHeart 6) in dogs

The FDA has received 198 reports of leucopenia in dogs after Moxidectin. That is 0.4% of all reports for this medicine, compared with 0.3% across reports for all dog medicines.

198Reports

47%Marked serious

7.6%Recovered

25%Died or euthanised

2 daysTypical onset

How soon it started

Same day

42 35%

1–2 days

22 18%

3–7 days

24 20%

1–4 weeks

21 17%

Over a month

12 9.9%

How the animals did

Recovered

15 7.6%

Still unwell when reported

89 45%

Died

36 18%

Euthanised

14 7.1%

Not known

44 22%

Problems reported at the same time

119 60%

90 45%

86 43%

82 41%

82 41%

56 28%

51 26%

48 24%

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 leucopenia in dogs?: 198 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 2 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).

Leucopenia with similar medicines

Leucopenia after Ivermectin + Pyrantel (Heartgard Plus) 100 reports · 0.1% of its reports
Leucopenia after Milbemycin Oxime + Spinosad (Trifexis) 109 reports · 0.1% of its reports
Leucopenia after Milbemycin Oxime + Praziquantel (Interceptor Plus) 25 reports · 0.1% of its reports
Leucopenia after Milbemycin Oxime (Interceptor) 40 reports · 0.1% of its reports
Leucopenia after Selamectin (Revolution) 47 reports · 0.2% of its reports
Leucopenia after Ivermectin (Heartgard) 35 reports · 0.3% of its reports

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