Reaction profile

The FDA adverse-event record for megaoesophagus

132 FDA adverse-event reports reference megaoesophagus (VeDDRA 274). See the species, breeds, and drugs most associated with it below.

132
reports citing this reaction
38.6%
death-coded share
Dog
most-affected species
Afoxolaner
most-associated drug
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132
Total Reports
51
Deaths
38.6%
Death Rate

Species Most Affected

Dog 127
Cat 4
Cattle 1

Breeds Most Affected

Retriever - Labrador 20
Shepherd Dog - German 8
Crossbred Canine/dog 7
Retriever - Golden 6
Dog (unknown) 6
Deutsche Dogge, Great Dane 4
Cattle Dog - Australian (blue heeler, red heeler, Queensland cattledog) 4
Chihuahua 4
Domestic Shorthair 4
Maltese 3

Associated Drugs

Afoxolaner 16
Oclacitinib Maleate 14
Carprofen 12
Trilostane 11
Milbemycin Oxime + Spinosad 10
Maropitant Citrate 10
Ivermectin + Pyrantel As Pamoate Salt 10
Bedinvetmab 10
Spinosad 8
Fluralaner Chew Tablets 6
Enrofloxacin 5
Fluralaner 13.64% 12-Week Chew 5
Maropitant 4
Sucralfate 4
Omeprazole 4
Moxidectin 4
Pyrantel Pamoate;Sarolaner 4
Rabies Vaccine 3
Ivermectin 3
Famotidine 3

Megaoesophagus Reaction Insights

132 reports name Megaoesophagus; 51 recorded a death outcome (38.6% of reported events, not a population-level mortality rate). VeDDRA code: 274.

By species: Dog (127 reports), Cat (4 reports), Cattle (1 reports). By breed: Retriever - Labrador (20), Shepherd Dog - German (8), Crossbred Canine/dog (7).

Most co-reported drugs: Afoxolaner (16 reports), Oclacitinib Maleate (14 reports), Carprofen (12 reports), Trilostane (11 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.