Reaction profile

The FDA adverse-event record for horner's syndrome

520 FDA adverse-event reports reference horner's syndrome (VeDDRA 702). See the species, breeds, and drugs most associated with it below.

520
reports citing this reaction
8.3%
death-coded share
Cat
most-affected species
Florfenicol + Mometasone Furoate + Terbinafine Hydrochloride
most-associated drug
Verify with FDA CVM →
520
Total Reports
43
Deaths
8.3%
Death Rate

Species Most Affected

Cat 297
Dog 218
Horse 2
Ferret 2
Other 1

Breeds Most Affected

Domestic Shorthair 189
Retriever - Labrador 55
Cat (unknown) 25
Retriever - Golden 23
Domestic Mediumhair 16
Domestic Longhair 15
Boxer (German Boxer) 11
Crossbred Canine/dog 10
Domestic (unspecified) 9
Spaniel (unspecified) 8

Associated Drugs

Florfenicol + Mometasone Furoate + Terbinafine Hydrochloride 156
Betamethasone + Florfenicol + Terbinafine 43
Maropitant Citrate 34
Bedinvetmab 33
Florfenicol/Terbinafine Hydrochloride/Mometasone Furoate 32
Florfenicol, Terbinafine, Betamethasone Acetate 31
Prednisone 23
Oclacitinib Maleate 21
Trilostane 19
Gabapentin 19
Ear Cleaner 19
Buprenorphine 18
Cefovecin 16
Mirtazapine 16
Prednisolone 14
Carprofen 13
Cefovecin Sodium 13
Milbemycin Oxime + Spinosad 13
Enrofloxacin 13
Rabies Vaccine 13

Horner's syndrome Reaction Insights

520 reports name Horner's syndrome; 43 recorded a death outcome (8.3% of reported events, not a population-level mortality rate). VeDDRA code: 702.

By species: Cat (297 reports), Dog (218 reports), Horse (2 reports). By breed: Domestic Shorthair (189), Retriever - Labrador (55), Cat (unknown) (25).

Most co-reported drugs: Florfenicol + Mometasone Furoate + Terbinafine Hydrochloride (156 reports), Betamethasone + Florfenicol + Terbinafine (43 reports), Maropitant Citrate (34 reports), Bedinvetmab (33 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.