Lameness after Milbemycin Oxime (Interceptor) in dogs

115 reports to the FDA describe lameness in dogs given Milbemycin Oxime. 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.

115Reports

27%Marked serious

7.8%Recovered

3.5%Died or euthanised

36 daysTypical onset

How soon it started

Same day

9 26%

1–2 days

3 8.8%

3–7 days

1 2.9%

1–4 weeks

2 5.9%

Over a month

19 56%

How the animals did

Recovered

9 7.8%

Still unwell when reported

33 29%

Died

2 1.7%

Euthanised

2 1.7%

Not known

69 60%

Problems reported at the same time

26 23%

19 17%

15 13%

15 13%

14 12%

14 12%

10 8.7%

Didn't prevent heartworm

10 8.7%

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 lameness in dogs?: 115 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 36 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).

Lameness with similar medicines

Lameness after Ivermectin + Pyrantel (Heartgard Plus) 319 reports · 0.2% of its reports
Lameness after Milbemycin Oxime + Spinosad (Trifexis) 452 reports · 0.3% of its reports
Lameness after Moxidectin (ProHeart 6) 363 reports · 0.7% of its reports
Lameness after Milbemycin Oxime + Praziquantel (Interceptor Plus) 233 reports · 0.7% of its reports
Lameness after Selamectin (Revolution) 100 reports · 0.3% of its reports
Lameness after Ivermectin (Heartgard) 59 reports · 0.5% of its reports

All reported side effects of Milbemycin Oxime in dogs · Medicines most reported with lameness