Drug profile

The FDA adverse-event record for Spinosad/Milbemycin Oxime

269 adverse-event reports submitted to the FDA Center for Veterinary Medicine reference Spinosad/Milbemycin Oxime. See the species affected, top reactions, and outcomes below.

269
adverse-event reports
1.1%
death-coded share
Dog
most-reported species
179
INEFFECTIVE, HEARTWORM LARVAE - top reaction
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Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
269
Total Reports
3
Deaths Reported
1.1%
Death Rate

Active Ingredients

Spinosad/Milbemycin Oxime

Administration Routes

OralUnknown

Species Affected

Dog 269

Most Affected Breeds

Retriever - Labrador 59
Crossbred Canine/dog 35
Shepherd Dog - German 14
Boxer (German Boxer) 12
Pit Bull 12
Retriever - Golden 11
Beagle 11
Chihuahua 8
Dachshund (unspecified) 6
Collie (unspecified) 5

Most Reported Reactions

INEFFECTIVE, HEARTWORM LARVAE 179
Lack of efficacy - NOS 28
Vomiting 17
Lethargy (see also Central nervous system depression in 'Neurological') 11
Lack of efficacy (endoparasite) - heartworm 11
Underdose 10
Diarrhoea 10
Lack of efficacy (heartworm) 10
Other abnormal test result NOS 8
Pruritus 7
Anorexia 6
Lack of efficacy (endoparasite) - tapeworm 5

Outcome Breakdown

Ongoing
117 (43.5%)
Outcome Unknown
101 (37.5%)
Recovered/Normal
46 (17.1%)
Died
3 (1.1%)
Recovered with Sequela
2 (0.7%)

Spinosad/Milbemycin Oxime Adverse Event Insights

269 reports name Spinosad/Milbemycin Oxime; 3 recorded a death outcome (1.1% of reported events, not a population-level mortality rate). Active ingredient: Spinosad/Milbemycin Oxime. Administration routes: Oral, Unknown.

By species: Dog (269 reports). By breed: Retriever - Labrador (59), Crossbred Canine/dog (35), Shepherd Dog - German (14).

Leading clinical signs: INEFFECTIVE, HEARTWORM LARVAE (179), Lack of efficacy - NOS (28), Vomiting (17), Lethargy (see also Central nervous system depression in 'Neurological') (11). Outcome, 269 coded reports: Ongoing leads at 43.5%.

Read these counts as reporting volume, not risk: per our methodology, a widely-prescribed drug will rack up more raw FDA reports in a given year than a rarely-used one at an identical true rate, so we recommend comparing within similar-exposure products rather than across the full 2025 catalog.

Source: FDA Center for Veterinary Medicine openFDA Animal & Veterinary Adverse Events (CVM AER) · 2025

Every figure on PlainBreed is rendered directly from FDA openFDA adverse event data, no number is typed in by an editor. This page draws directly on FDA openFDA data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.