Leucocytosis after Milbemycin Oxime (Interceptor) in dogs

134 reports to the FDA describe leucocytosis in dogs given Milbemycin Oxime. That is 0.5% 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.

134Reports

22%Marked serious

4.5%Recovered

31%Died or euthanised

4 daysTypical onset

How soon it started

Same day

6 24%

1–2 days

5 20%

3–7 days

4 16%

1–4 weeks

3 12%

Over a month

7 28%

How the animals did

Recovered

5 3.7%

Recovered with lasting effects

1 0.7%

Still unwell when reported

20 15%

Died

37 28%

Euthanised

5 3.7%

Not known

66 49%

Problems reported at the same time

66 49%

64 48%

64 48%

56 42%

41 31%

40 30%

36 27%

35 26%

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).

Products with this ingredient include Interceptor. 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 cause leucocytosis in dogs?: 134 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 4 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 + Praziquantel (Interceptor Plus) 136 reports · 0.4% 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 in dogs · Medicines most reported with leucocytosis