Reaction profile

The FDA adverse-event record for lethargy (see also central nervous system depression in 'neurological')

75,886 FDA adverse-event reports reference lethargy (see also central nervous system depression in 'neurological') (VeDDRA 1018). See the species, breeds, and drugs most associated with it below.

75,886
reports citing this reaction
8.4%
death-coded share
Dog
most-affected species
Milbemycin Oxime + Spinosad
most-associated drug
Verify with FDA CVM →
75,886
Total Reports
6,399
Deaths
8.4%
Death Rate

Species Most Affected

Dog 65,152
Cat 9,864
Horse 417
Cattle 199
Human 50
Pig 47
Unknown 27
Rabbit 24
Goat 15
Sheep 14

Breeds Most Affected

Domestic Shorthair 5,954
Retriever - Labrador 5,869
Crossbred Canine/dog 4,285
Chihuahua 3,541
Terrier - Yorkshire 2,984
Retriever - Golden 2,730
Shih Tzu 2,587
Boxer (German Boxer) 2,285
Maltese 1,928
Shepherd Dog - German 1,860

Associated Drugs

Milbemycin Oxime + Spinosad 20,659
Spinosad 5,205
Afoxolaner 5,200
Moxidectin 3,738
Fluralaner Chew Tablets 3,354
Ivermectin + Pyrantel As Pamoate Salt 3,049
Carprofen 2,794
Trilostane 2,678
Imidacloprid + Moxidectin 2,397
Selamectin 2,293
Maropitant Citrate 2,284
Oclacitinib Maleate 2,121
Pyrantel Pamoate;Sarolaner 1,983
Milbemycin Oxime + Praziquantel 1,799
Cefovecin 1,758
Sarolaner 1,592
Nitenpyram 1,290
Prednisone 1,163
Fluralaner 13.64% 12-Week Chew 1,121
Fluralaner Spot-On Solution 1,058

Lethargy (see also Central nervous system depression in 'Neurological') Reaction Insights

75,886 reports name Lethargy (see also Central nervous system depression in 'Neurological'); 6,399 recorded a death outcome (8.4% of reported events, not a population-level mortality rate). VeDDRA code: 1018.

By species: Dog (65,152 reports), Cat (9,864 reports), Horse (417 reports). By breed: Domestic Shorthair (5,954), Retriever - Labrador (5,869), Crossbred Canine/dog (4,285).

Most co-reported drugs: Milbemycin Oxime + Spinosad (20,659 reports), Spinosad (5,205 reports), Afoxolaner (5,200 reports), Moxidectin (3,738 reports).

Read these counts as reporting volume, not risk: per our methodology, co-reporting reflects temporal association captured in voluntary submissions, not proof that a drug caused this reaction. A widely-prescribed drug will rack up more raw co-reports at an identical true rate than a rarely-used one, so compare within similar-exposure products.

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.