Lymphopenia after Moxidectin (ProHeart 6) in dogs

139 reports to the FDA describe lymphopenia in dogs given Moxidectin. That is 0.3% of all reports for this medicine, compared with 0.3% across reports for all dog medicines.

139Reports

58%Marked serious

6.5%Recovered

35%Died or euthanised

2 daysTypical onset

How soon it started

Same day

23 24%

1–2 days

28 30%

3–7 days

18 19%

1–4 weeks

10 11%

Over a month

15 16%

How the animals did

Recovered

9 6.5%

Still unwell when reported

58 42%

Died

27 19%

Euthanised

21 15%

Not known

24 17%

Problems reported at the same time

84 60%

78 56%

75 54%

69 50%

50 36%

49 35%

45 32%

39 28%

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 lymphopenia in dogs?: 139 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).

Lymphopenia with similar medicines

Lymphopenia after Ivermectin + Pyrantel (Heartgard Plus) 146 reports · 0.1% of its reports
Lymphopenia after Milbemycin Oxime + Spinosad (Trifexis) 179 reports · 0.1% of its reports
Lymphopenia after Milbemycin Oxime + Praziquantel (Interceptor Plus) 48 reports · 0.2% of its reports
Lymphopenia after Milbemycin Oxime (Interceptor) 35 reports · 0.1% of its reports
Lymphopenia after Selamectin (Revolution) 26 reports · 0.1% of its reports
Lymphopenia after Ivermectin (Heartgard) 36 reports · 0.3% of its reports

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