Reaction profile
The FDA adverse-event record for low thyroxine (t4)
653 FDA reports name low thyroxine (t4), a high-volume reaction in the CVM extract (VeDDRA 2670). Plate stamps and neighbourhood peers follow.
- #537 of 2,481
- by report volume (all reactions)
- 653
- reports citing this reaction
- 18.4%
- death-coded share
- Dog
- most-affected species
Release-over-release change
What changed in the latest FDA data snapshot
PlainBreed reconstructed the prior snapshot from dated openFDA partitions through 2025 Q4, then compared it with the 2026-07-27 openFDA export. Low thyroxine (T4) has 653 reports now versus 621 in that prior snapshot: 32 more (5.2%).
- Report change
- +32
- Death-coded reports
- +8
- Death-coded share
- +0.3 pts
This compares reported-event counts in two source snapshots. It does not establish a change in real-world risk, product safety, or disease incidence.
Subscribe to Low thyroxine (T4) changesFDA AER · VeDDRA plate
Code 2670 VOL-MID
VOL-MID · DEATH-ELEV · UPPER-Q · PHOTO-FINISH · SPECIES-DOG · DRUG-LEAD · DESK-WIDE · BOOK-FULL
- VOL-MID 653 reports
- DEATH-ELEV 18.4%
- UPPER-Q #537/2481
- PHOTO-FINISH Dull
- SPECIES-DOG Dog · 583
- DRUG-LEAD Trilostane · 176
- DESK-WIDE 20 breeds
- BOOK-FULL 8/8 fields
Nearest volume peer: Dull (±1 reports)
Upper-third report volume drives the scale stamps on this plate; death-coded share and co-report peers follow. Not a clinical diagnosis.
High-volume neighbourhood around Low thyroxine
Upper-third volume poles plus nearest peers, not a full reaction corpus board reprint.
What the FDA AER plate says about Low thyroxine (T4)
Signature read: 120 death-coded reports is a heavy tail count for Low thyroxine (T4) in the CVM extract. Report volume is upper-third scale: 653 named reports in the openFDA extract. 120 of 653 reports were death-coded (18.4% of named reports, not a population mortality rate). Nearest volume peer: Dull (±1 reports). Lead species Dog (583). Lead co-reported drug Trilostane (176).
Read these counts as reporting volume, not risk: per our methodology, Lead co-reported drug Trilostane appears in filings alongside this reaction; that is association, not causation. Browse the full reactions index or the about page for how PlainBreed frames FDA CVM extracts.
Species Most Affected
Breeds Most Affected
Associated Drugs
Nationwide reactions with similar profiles
Two openFDA-derived peer sets for Low thyroxine (T4), both floored at ≥50 reports so the neighborhoods stay in the advertised mass (the volume chart above is the unfloored photo-finish strip).
Similar report volume
Nearest other reactions by FDA report count (653 here).
Similar death-coded share
Nearest other reactions by death-coded share (18.4% here), distinct from the volume row.
What to do with this reaction
- Compare Low thyroxine's report profile against similar reactions nationwide. See similar reactions
- Read how death-coded share differs from a mortality rate before drawing conclusions. Understanding adverse events
- Browse the full reaction directory to compare report counts across reaction types. All reactions
A report does not prove a drug caused the reaction; consult a veterinarian before acting on this data.
Source: FDA Center for Veterinary Medicine openFDA Animal & Veterinary Adverse Events (CVM AER) · 2025
Informational only. FDA adverse-event reports are voluntary and do not prove causation; consult a veterinarian before acting on them. Verify with FDA CVM →