Lethargy after Moxidectin (ProHeart 6) in dogs

6,640 reports to the FDA describe lethargy in dogs given Moxidectin. That is 13% of all reports for this medicine, compared with 11% across reports for all dog medicines.

6,640Reports

44%Marked serious

22%Recovered

12%Died or euthanised

Same dayTypical onset

How soon it started

Same day

3,005 63%

1–2 days

809 17%

3–7 days

366 7.7%

1–4 weeks

267 5.6%

Over a month

293 6.2%

How the animals did

Recovered

1,428 22%

Recovered with lasting effects

8 0.1%

Still unwell when reported

2,724 41%

Died

585 8.8%

Euthanised

240 3.6%

Not known

1,655 25%

Problems reported at the same time

3,463 52%

2,180 33%

1,767 27%

1,377 21%

1,019 15%

881 13%

832 13%

767 12%

Age of the animals

Under 1 year

482

1–3 years

2,735

4–7 years

1,914

8–11 years

1,049

12+ years

350

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 lethargy in dogs?: 6,640 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).

Lethargy with similar medicines

Lethargy after Ivermectin + Pyrantel (Heartgard Plus) 7,391 reports · 5.0% of its reports
Lethargy after Milbemycin Oxime + Spinosad (Trifexis) 19,835 reports · 15% of its reports
Lethargy after Milbemycin Oxime + Praziquantel (Interceptor Plus) 2,407 reports · 7.6% of its reports
Lethargy after Milbemycin Oxime (Interceptor) 2,528 reports · 8.5% of its reports
Lethargy after Selamectin (Revolution) 2,964 reports · 10% of its reports
Lethargy after Ivermectin (Heartgard) 1,488 reports · 12% of its reports
Lethargy after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 969 reports · 11% of its reports
Lethargy after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 135 reports · 12% of its reports
Lethargy after Ivermectin + Praziquantel 35 reports · 17% of its reports
Lethargy after Moxidectin + Praziquantel 21 reports · 28% of its reports

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