Didn't work as expected after Moxidectin (ProHeart 6) in dogs

2,005 reports to the FDA describe didn't work as expected in dogs given Moxidectin. That is 4.0% of all reports for this medicine, compared with 13% across reports for all dog medicines, so it is reported less often than average with this medicine.

2,005Reports

37%Marked serious

3.7%Recovered

1.6%Died or euthanised

164 daysTypical onset

How soon it started

Same day

82 7.4%

1–2 days

45 4.1%

3–7 days

30 2.7%

1–4 weeks

97 8.7%

Over a month

857 77%

How the animals did

Recovered

74 3.7%

Still unwell when reported

1,736 87%

Died

15 0.7%

Euthanised

18 0.9%

Not known

162 8.1%

Problems reported at the same time

Didn't prevent heartworm

813 41%

241 12%

139 6.9%

89 4.4%

81 4.0%

80 4.0%

46 2.3%

41 2.0%

Age of the animals

Under 1 year

1–3 years

954

4–7 years

574

8–11 years

276

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 didn't work as expected in dogs?: 2,005 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 164 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).

Didn't work as expected with similar medicines

Didn't work as expected after Ivermectin + Pyrantel (Heartgard Plus) 27,781 reports · 19% of its reports
Didn't work as expected after Milbemycin Oxime + Spinosad (Trifexis) 13,050 reports · 10% of its reports
Didn't work as expected after Milbemycin Oxime + Praziquantel (Interceptor Plus) 3,979 reports · 13% of its reports
Didn't work as expected after Milbemycin Oxime (Interceptor) 3,131 reports · 11% of its reports
Didn't work as expected after Selamectin (Revolution) 2,253 reports · 7.7% of its reports
Didn't work as expected after Ivermectin (Heartgard) 741 reports · 6.2% of its reports
Didn't work as expected after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 1,337 reports · 16% of its reports
Didn't work as expected after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 123 reports · 11% of its reports

All reported side effects of Moxidectin in dogs · Medicines most reported with didn't work as expected