Breathing problems after Milbemycin Oxime (Interceptor) in dogs

The FDA has received 481 reports of breathing problems in dogs after Milbemycin Oxime. That is 1.6% of all reports for this medicine, compared with 2.7% across reports for all dog medicines, so it is reported less often than average with this medicine.

481Reports
25%Marked serious
12%Recovered
23%Died or euthanised
2 daysTypical onset
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How soon it started

Same day
49 40%
1–2 days
19 15%
3–7 days
3 2.4%
1–4 weeks
11 8.9%
Over a month
42 34%

How the animals did

Recovered
54 11%
Recovered with lasting effects
5 1.0%
Still unwell when reported
45 9.4%
Died
90 19%
Euthanised
19 4.0%
Not known
268 56%

Problems reported at the same time

Age of the animals

Under 1 year
49
1–3 years
131
4–7 years
143
8–11 years
108
12+ years
40

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 breathing problems in dogs?
481 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 2 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).

Breathing problems with similar medicines

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