Low platelet count after Milbemycin Oxime + Praziquantel (Interceptor Plus) in dogs

The FDA has received 75 reports of low platelet count in dogs after Milbemycin Oxime + Praziquantel. That is 0.2% of all reports for this medicine, compared with 0.2% across reports for all dog medicines.

75Reports

73%Marked serious

6.7%Recovered

11%Died or euthanised

23 daysTypical onset

How soon it started

Same day

7 18%

1–2 days

3 7.5%

3–7 days

3 7.5%

1–4 weeks

8 20%

Over a month

19 48%

How the animals did

Recovered

5 6.7%

Still unwell when reported

34 45%

Died

4 5.3%

Euthanised

4 5.3%

Not known

28 37%

Problems reported at the same time

28 37%

23 31%

21 28%

21 28%

17 23%

17 23%

14 19%

14 19%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Milbemycin Oxime prevents heartworm and controls some intestinal worms (monthly). Praziquantel treats tapeworms.

Products with this combination include Interceptor 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 Milbemycin Oxime + Praziquantel cause low platelet count in dogs?: 75 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 23 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).

Low platelet count with similar medicines

Low platelet count after Ivermectin + Pyrantel (Heartgard Plus) 137 reports · 0.1% of its reports
Low platelet count after Milbemycin Oxime + Spinosad (Trifexis) 159 reports · 0.1% of its reports
Low platelet count after Moxidectin (ProHeart 6) 151 reports · 0.3% of its reports
Low platelet count after Ivermectin (Heartgard) 31 reports · 0.3% of its reports

All reported side effects of Milbemycin Oxime + Praziquantel in dogs · Medicines most reported with low platelet count