Tachycardia after Moxidectin (ProHeart 6) in dogs

The FDA has received 628 reports of tachycardia in dogs after Moxidectin. That is 1.2% of all reports for this medicine, compared with 0.5% across reports for all dog medicines, so it is reported unusually often with this medicine.

628Reports

70%Marked serious

33%Recovered

12%Died or euthanised

Same dayTypical onset

How soon it started

Same day

449 86%

1–2 days

24 4.6%

3–7 days

13 2.5%

1–4 weeks

13 2.5%

Over a month

22 4.2%

How the animals did

Recovered

207 33%

Recovered with lasting effects

1 0.2%

Still unwell when reported

250 40%

Died

53 8.4%

Euthanised

23 3.7%

Not known

94 15%

Problems reported at the same time

448 71%

398 63%

231 37%

197 31%

183 29%

163 26%

160 25%

133 21%

Age of the animals

Under 1 year

1–3 years

335

4–7 years

143

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 tachycardia in dogs?: 628 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).

Tachycardia with similar medicines

Tachycardia after Ivermectin + Pyrantel (Heartgard Plus) 204 reports · 0.1% of its reports
Tachycardia after Milbemycin Oxime + Spinosad (Trifexis) 209 reports · 0.2% of its reports
Tachycardia after Milbemycin Oxime + Praziquantel (Interceptor Plus) 55 reports · 0.2% of its reports
Tachycardia after Milbemycin Oxime (Interceptor) 78 reports · 0.3% of its reports
Tachycardia after Selamectin (Revolution) 86 reports · 0.3% of its reports
Tachycardia after Ivermectin (Heartgard) 82 reports · 0.7% of its reports
Tachycardia after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 32 reports · 0.4% of its reports

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