Leucocytosis after Milbemycin Oxime + Praziquantel (Interceptor Plus) in dogs

The FDA has received 136 reports of leucocytosis in dogs after Milbemycin Oxime + Praziquantel. That is 0.4% of all reports for this medicine, compared with 1.0% across reports for all dog medicines, so it is reported less often than average with this medicine.

136Reports

66%Marked serious

15%Recovered

14%Died or euthanised

30 daysTypical onset

How soon it started

Same day

9 10%

1–2 days

12 13%

3–7 days

8 9.0%

1–4 weeks

16 18%

Over a month

44 49%

How the animals did

Recovered

20 15%

Recovered with lasting effects

1 0.7%

Still unwell when reported

46 34%

Died

9 6.6%

Euthanised

10 7.4%

Not known

50 37%

Problems reported at the same time

66 49%

56 41%

54 40%

53 39%

49 36%

43 32%

42 31%

28 21%

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 leucocytosis in dogs?: 136 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 30 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).

Leucocytosis with similar medicines

Leucocytosis after Ivermectin + Pyrantel (Heartgard Plus) 401 reports · 0.3% of its reports
Leucocytosis after Milbemycin Oxime + Spinosad (Trifexis) 474 reports · 0.4% of its reports
Leucocytosis after Moxidectin (ProHeart 6) 773 reports · 1.5% of its reports
Leucocytosis after Milbemycin Oxime (Interceptor) 134 reports · 0.5% of its reports
Leucocytosis after Selamectin (Revolution) 172 reports · 0.6% of its reports
Leucocytosis after Ivermectin (Heartgard) 109 reports · 0.9% of its reports
Leucocytosis after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 22 reports · 0.3% of its reports

All reported side effects of Milbemycin Oxime + Praziquantel in dogs · Medicines most reported with leucocytosis