Drug profile

The FDA adverse-event record for Milbemycin/Praziquantel

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

217
adverse-event reports
1.8%
death-coded share
Dog
most-reported species
103
Lack of efficacy (endoparasite) - heartworm - 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.
217
Total Reports
4
Deaths Reported
1.8%
Death Rate

Active Ingredients

Milbemycin/Praziquantel

Administration Routes

OralUnknown

Species Affected

Dog 217

Most Affected Breeds

Retriever - Labrador 41
Crossbred Canine/dog 12
Terrier - Bull - American Pit 12
Retriever - Golden 11
Chihuahua 8
Dog (unknown) 7
Beagle 7
Shepherd Dog - German 7
Great Pyrenees 7
Terrier (unspecified) 6

Most Reported Reactions

Lack of efficacy (endoparasite) - heartworm 103
Vomiting 30
Seizure NOS 26
Lethargy (see also Central nervous system depression in 'Neurological') 17
Ataxia 11
Tremor 10
Diarrhoea 7
Anorexia 7
Shaking 6
Head tremor 6
Behavioural disorder NOS 5
Restlessness 5

Outcome Breakdown

Ongoing
152 (70.0%)
Recovered/Normal
33 (15.2%)
Outcome Unknown
28 (12.9%)
Died
3 (1.4%)
Euthanized
1 (0.5%)

Milbemycin/Praziquantel Adverse Event Insights

217 reports name Milbemycin/Praziquantel; 4 recorded a death outcome (1.8% of reported events, not a population-level mortality rate). Active ingredient: Milbemycin/Praziquantel. Administration routes: Oral, Unknown.

By species: Dog (217 reports). By breed: Retriever - Labrador (41), Crossbred Canine/dog (12), Terrier - Bull - American Pit (12).

Leading clinical signs: Lack of efficacy (endoparasite) - heartworm (103), Vomiting (30), Seizure NOS (26), Lethargy (see also Central nervous system depression in 'Neurological') (17). Outcome, 217 coded reports: Ongoing leads at 70.0%.

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.