Hyperphosphataemia after Ivermectin + Pyrantel (Heartgard Plus) in dogs

The FDA has received 164 reports of hyperphosphataemia in dogs after Ivermectin + Pyrantel. That is 0.1% of all reports for this medicine, compared with 0.6% across reports for all dog medicines, so it is reported less often than average with this medicine.

164Reports

66%Marked serious

18%Recovered

29%Died or euthanised

3 daysTypical onset

How soon it started

Same day

24 23%

1–2 days

26 25%

3–7 days

12 12%

1–4 weeks

14 13%

Over a month

28 27%

How the animals did

Recovered

26 16%

Recovered with lasting effects

3 1.8%

Still unwell when reported

28 17%

Died

22 13%

Euthanised

25 15%

Not known

60 37%

Problems reported at the same time

95 58%

90 55%

88 54%

71 43%

60 37%

47 29%

46 28%

45 27%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Ivermectin prevents heartworm disease (monthly). Pyrantel treats roundworms and hookworms.

Products with this combination include Heartgard Plus, Tri-Heart Plus, Iverhart Plus. 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 Ivermectin + Pyrantel cause hyperphosphataemia in dogs?: 164 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 3 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).

Hyperphosphataemia with similar medicines

Hyperphosphataemia after Milbemycin Oxime + Spinosad (Trifexis) 236 reports · 0.2% of its reports
Hyperphosphataemia after Moxidectin (ProHeart 6) 219 reports · 0.4% of its reports
Hyperphosphataemia after Milbemycin Oxime + Praziquantel (Interceptor Plus) 56 reports · 0.2% of its reports
Hyperphosphataemia after Milbemycin Oxime (Interceptor) 59 reports · 0.2% of its reports
Hyperphosphataemia after Selamectin (Revolution) 57 reports · 0.2% of its reports
Hyperphosphataemia after Ivermectin (Heartgard) 44 reports · 0.4% of its reports

All reported side effects of Ivermectin + Pyrantel in dogs · Medicines most reported with hyperphosphataemia