Bradycardia after Moxidectin (ProHeart 6) in dogs

267 reports to the FDA describe bradycardia in dogs given Moxidectin. That is 0.5% of all reports for this medicine, compared with 0.3% across reports for all dog medicines, so it is reported unusually often with this medicine.

267Reports

72%Marked serious

40%Recovered

7.5%Died or euthanised

Same dayTypical onset

How soon it started

Same day

192 89%

1–2 days

7 3.3%

3–7 days

4 1.9%

1–4 weeks

6 2.8%

Over a month

6 2.8%

How the animals did

Recovered

107 40%

Still unwell when reported

89 33%

Died

14 5.2%

Euthanised

6 2.2%

Not known

51 19%

Problems reported at the same time

200 75%

152 57%

130 49%

95 36%

73 27%

47 18%

47 18%

43 16%

Age of the animals

Under 1 year

1–3 years

159

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 bradycardia in dogs?: 267 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).

Bradycardia with similar medicines

Bradycardia after Ivermectin + Pyrantel (Heartgard Plus) 77 reports · 0.1% of its reports
Bradycardia after Milbemycin Oxime + Spinosad (Trifexis) 122 reports · 0.1% of its reports
Bradycardia after Milbemycin Oxime (Interceptor) 31 reports · 0.1% of its reports
Bradycardia after Selamectin (Revolution) 32 reports · 0.1% of its reports
Bradycardia after Ivermectin (Heartgard) 49 reports · 0.4% of its reports

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