Blood in urine after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 167 reports of blood in urine in dogs after Milbemycin Oxime + Spinosad. That is 0.1% of all reports for this medicine, compared with 0.2% across reports for all dog medicines.

167Reports

63%Marked serious

35%Recovered

21%Died or euthanised

11 daysTypical onset

How soon it started

Same day

27 22%

1–2 days

16 13%

3–7 days

14 11%

1–4 weeks

17 14%

Over a month

48 39%

How the animals did

Recovered

32 19%

Recovered with lasting effects

27 16%

Still unwell when reported

33 20%

Died

11 6.6%

Euthanised

24 14%

Not known

40 24%

Problems reported at the same time

69 41%

66 40%

63 38%

59 35%

42 25%

40 24%

34 20%

Urinary tract infection

33 20%

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). Spinosad kills fleas; monthly chewable.

Products with this combination include Trifexis. 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 + Spinosad cause blood in urine in dogs?: 167 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 11 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).

Blood in urine with similar medicines

Blood in urine after Ivermectin + Pyrantel (Heartgard Plus) 61 reports · 0.0% of its reports
Blood in urine after Moxidectin (ProHeart 6) 79 reports · 0.2% of its reports
Blood in urine after Milbemycin Oxime + Praziquantel (Interceptor Plus) 31 reports · 0.1% of its reports
Blood in urine after Ivermectin (Heartgard) 21 reports · 0.2% of its reports

All reported side effects of Milbemycin Oxime + Spinosad in dogs · Medicines most reported with blood in urine