Hyperphosphataemia after Ivermectin (Heartgard) in dogs

The FDA has received 44 reports of hyperphosphataemia in dogs after Ivermectin. That is 0.4% 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.

44Reports

80%Marked serious

14%Recovered

36%Died or euthanised

64 daysTypical onset

How soon it started

Same day

3 11%

1–2 days

2 7.4%

3–7 days

2 7.4%

1–4 weeks

3 11%

Over a month

17 63%

How the animals did

Recovered

5 11%

Recovered with lasting effects

1 2.3%

Still unwell when reported

15 34%

Died

5 11%

Euthanised

11 25%

Not known

7 16%

Problems reported at the same time

30 68%

25 57%

24 55%

22 50%

22 50%

17 39%

16 36%

14 32%

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).

Products with this ingredient include Heartgard. 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 cause hyperphosphataemia in dogs?: 44 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 64 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 Ivermectin + Pyrantel (Heartgard Plus) 164 reports · 0.1% of its reports
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

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