Reaction profile

The FDA adverse-event record for t4 low, serum

25 FDA adverse-event reports reference t4 low, serum (VeDDRA 93014). See the species, breeds, and drugs most associated with it below.

25
reports citing this reaction
24.0%
death-coded share
Dog
most-affected species
Levothyroxine Sodium
most-associated drug
Verify with FDA CVM →
25
Total Reports
6
Deaths
24.0%
Death Rate

Species Most Affected

Dog 24
Cat 1

Breeds Most Affected

Retriever - Labrador 5
Dachshund - Miniature 2
Dachshund (unspecified) 2
Terrier - Fox (unspecified) 1
Boxer (German Boxer) 1
Siamese 1
Havanese 1
Terrier - Yorkshire 1
Shepherd Dog - German 1
Whippet 1

Associated Drugs

Levothyroxine Sodium 8
Milbemycin Oxime + Spinosad 7
Meloxicam 2
Cefovecin 2
Trilostane 2
Phenobarbital 1
Carprofen 1
Feline Infectious Peritonitis(Ts) Virus, Df2-Ts, Mlv 1
Dexamethasone 1
Enrofloxacin 1
Anesthetic 1
Insulin Injectable Vial 1
Selamectin 1
Spinosad And Milbemycin Oxime 1
Spinosad 1
Carprofen (Unknown) 1
Tramadol 1
Grapiprant 1
Methocarbamol 1
Melarsomine Dihydrochloride 1

T4 LOW, SERUM Reaction Insights

25 reports name T4 LOW, SERUM; 6 recorded a death outcome (24.0% of reported events, not a population-level mortality rate). VeDDRA code: 93014.

By species: Dog (24 reports), Cat (1 reports). By breed: Retriever - Labrador (5), Dachshund - Miniature (2), Dachshund (unspecified) (2).

Most co-reported drugs: Levothyroxine Sodium (8 reports), Milbemycin Oxime + Spinosad (7 reports), Meloxicam (2 reports), Cefovecin (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.