Reaction profile

The FDA adverse-event record for high free thyroxine (ft4)

15 FDA adverse-event reports reference high free thyroxine (ft4) (VeDDRA 2704). See the species, breeds, and drugs most associated with it below.

15
reports citing this reaction
6.7%
death-coded share
Dog
most-affected species
Trilostane
most-associated drug
Verify with FDA CVM →
15
Total Reports
1
Deaths
6.7%
Death Rate

Species Most Affected

Dog 9
Cat 6

Breeds Most Affected

Domestic Shorthair 6
Dachshund - Standard Long-haired 2
Sheepdog - Shetland 1
Pinscher - Miniature 1
Coonhound - Black and Tan 1
Retriever - Labrador 1
Dalmatian 1
Crossbred Canine/dog 1
Bichon Frise 1

Associated Drugs

Trilostane 3
Fluralaner Spot-On Solution 2
Insulin Injectable Vial 2
Frunevetmab 2
Bedinvetmab 2
Penobarbital 2
Levothyroxine Sodium 1
Metronidazole 1
Propectalin 1
Melarsomine Dihydrochloride 1
Levothyroxine 1
Prednisone 1
Famotidine 1
Cefovecin 1
Emodepside + Praziquantel 1
Enrofloxacin 1
Feline Rhinotracheitis-Calici-Panleukopenia Vaccine, Modified Live Virus 1
Nitenpyram 1
Feline Calicivirus + Viral Rhinotracheitis Virus + Panleucopaenia Vaccine 1
Mirtazapine 1

High free thyroxine (FT4) Reaction Insights

15 reports name High free thyroxine (FT4); 1 recorded a death outcome (6.7% of reported events, not a population-level mortality rate). VeDDRA code: 2704.

By species: Dog (9 reports), Cat (6 reports). By breed: Domestic Shorthair (6), Dachshund - Standard Long-haired (2), Sheepdog - Shetland (1).

Most co-reported drugs: Trilostane (3 reports), Fluralaner Spot-On Solution (2 reports), Insulin Injectable Vial (2 reports), Frunevetmab (2 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.