Levothyroxine sodium (Thyro-Tabs Canine, ThyroKare): adverse event reports that FDA received
Active ingredient
The names in brackets are brand names with this active ingredient.
The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.
Read this first. FDA says this about the data:
An API dataset query result cannot be used to estimate the risk associated with the product or compare one drug or device product with another. When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event. This dataset should not be the sole source of information for clinical decision-making or other assumptions about the safety or effectiveness of a product. The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.
FDA Center for Veterinary Medicine publishes these words. Source: Adverse Event Reports for Animal Drugs and Devices, read on . The data have the reports that FDA received through .
This page is not veterinary advice. For an animal that is ill, speak to a veterinarian.
Contacting a veterinarianHow to report to FDAFrom June 1998 to June 2026, FDA received 3,218 adverse event reports that name a drug with levothyroxine sodium as its active ingredient. Of the 3,218 reports, 3,014 (93.7%) are about dogs. 92 reports are about people who were exposed to the drug (2.9%).
In January to March 2026, FDA received 69 reports that name this drug. The signs that appear in the largest number of the 3,218 reports are "Vomiting", "Lethargy" and "Diarrhoea". A report is not proof that a drug caused a sign.
Reports that name this drug fell by 13.6% in the 12 months to June 2026, compared with the 12 months before. Reports for all animal drugs fell by 4.6% in the same periods. The newest months can get more reports in a later update. Reports about dogs are 93.7% of the reports that name this drug, and 72.6% of all reports.
Since the last update of the FDA data
The site recorded an update of the FDA data on . FDA changed these counts for January to March 2026:
- All species: from 57 to 69.
- Dog: from 54 to 66.
January to March 2026 is the latest closed quarter in the data. In that quarter FDA received 69 reports that name levothyroxine sodium: 66 dog, 1 cat, 0 horse, 2 other or not given.
Signs that the reports list
A sign is a coded term from the report. The words in brackets are a plain gloss of the term. The percentage is the share of the 3,218 reports that list the sign. One report can list more than one sign.
The sign that is in the largest number of the reports comes first.
- Vomiting14.1%453 reports
- Lethargy[unusually tired or inactive]14%450 reports
- Diarrhoea[diarrhea]9.8%314 reports
- Emesis[vomiting]9.6%309 reports
- Lack of efficacy - NOS[the product did not have the expected effect]7.7%247 reports
- Weight loss6.5%209 reports
- Overdose[more than the labelled amount was given]5.8%186 reports
- Panting5.7%184 reports
- Seizure NOS[seizure, type not specified]5.7%184 reports
- Other abnormal test result NOS[abnormal laboratory result, type not specified]5.7%183 reports
- Elevated alanine aminotransferase (ALT)[a liver enzyme above the normal range]5.5%176 reports
- Anorexia[not eating]5.4%174 reports
- Death by euthanasia[the animal was euthanized]5.3%169 reports
- Polydipsia[drinking more than usual]5%162 reports
Show the next 16 signs
- Elevated serum alkaline phosphatase (SAP)[a liver and bone enzyme above the normal range]4.7%150 reports
- Polyuria[passing more urine than usual]4.2%134 reports
- Decreased appetite4%128 reports
- Not eating3.6%116 reports
- Elevated thyroxine (T4)3.3%107 reports
- Behavioural disorder NOS[behaviour change, type not specified]3%96 reports
- Ataxia[unsteady, uncoordinated movement]3%95 reports
- Elevated blood urea nitrogen (BUN)[a kidney value above the normal range]2.8%90 reports
- Low thyroxine (T4)2.8%89 reports
- Itching2.7%87 reports
- Abnormal radiograph finding2.5%79 reports
- Pruritus[itching]2.4%77 reports
- Weakness2.4%77 reports
- Abnormal ultrasound finding2.3%75 reports
- Inappetence[reduced appetite]2.3%75 reports
- Death2.3%74 reports
The list shows 30 of 1,364 coded signs. A report is not proof that a drug caused a sign. Download all signs (CSV)
Reports by species
The share is of all 3,218 reports that name levothyroxine sodium. The other reports give a different species or no species.
Reports for each month, Jul 2021 to Jun 2026
No chart: no month has 5 or more reports.
No chart: no month has 5 or more reports.
No chart: no month has 5 or more reports.
The month is the month in which FDA received the report. Each chart has its own scale. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.
Reports by year
- Dog
- Cat
- Horse
- Other or not given
| Year | Dog | Cat | Horse | Other or not given | All species |
|---|---|---|---|---|---|
| 2026 | 118 | 2 | 1 | 2 | 123 |
| 2025 | 273 | 5 | 3 | 13 | 294 |
| 2024 | 247 | 3 | 1 | 10 | 261 |
| 2023 | 131 | 5 | 1 | 13 | 150 |
| 2022 | 112 | 0 | 0 | 5 | 117 |
| 2021 | 131 | 1 | 1 | 10 | 143 |
| 2020 | 158 | 2 | 0 | 11 | 171 |
| 2019 | 146 | 1 | 0 | 14 | 161 |
| 2018 | 220 | 2 | 0 | 15 | 237 |
| 2017 | 243 | 0 | 0 | 18 | 261 |
| 2016 | 231 | 1 | 0 | 12 | 244 |
| 2015 | 140 | 1 | 0 | 7 | 148 |
| 2014 | 181 | 2 | 0 | 13 | 196 |
| 2013 | 284 | 1 | 1 | 6 | 292 |
| 2012 | 329 | 2 | 0 | 11 | 342 |
| 2011 | 35 | 0 | 1 | 0 | 36 |
| 2010 | 6 | 1 | 0 | 0 | 7 |
| 2009 | 5 | 0 | 0 | 4 | 9 |
| 2008 | 3 | 0 | 0 | 0 | 3 |
| 2007 | 6 | 0 | 0 | 0 | 6 |
| 2006 | 3 | 0 | 0 | 2 | 5 |
| 2003 | 7 | 0 | 0 | 0 | 7 |
| 2001 | 3 | 0 | 0 | 0 | 3 |
| 1999 | 1 | 0 | 0 | 0 | 1 |
| 1998 | 1 | 0 | 0 | 0 | 1 |
2026 has the reports that FDA received through Jun 2026. Download the years (CSV)
What the reports record
Outcome at the time of the report
- Recovered/Normal32.7%1,053
- Recovered with Sequela[recovered, with a lasting effect]2.8%90
- Ongoing26.1%840
- Died2.7%87
- Euthanized5.2%167
- Outcome Unknown27.5%885
An outcome in a report is not proof that the drug caused it. The person who sends the report gives the outcome. Each share is of the 3,218 reports that name levothyroxine sodium.
A report about more than one animal can have more than one outcome.
Kind of report
- Safety issue80.7%2,598
- Lack of expected effectiveness6%193
- Both safety and lack of expected effectiveness8.2%263
- Manufacturing or product defect5.1%163
- Otherunder 0.1%1
3,059 reports say if the event was serious. 45.2% of them have the serious flag. The person who sends the report sets the flag.
Show age, weight, breed and route
Age of the animal
- Under 1 year0.3%9
- 1 to 3 years3%97
- 4 to 7 years20.1%647
- 8 to 11 years39.2%1,262
- 12 years and over33.3%1,071
- Age not given4.1%132
Weight of the animal
- Under 5 kg (11 lb)5.9%191
- 5 to 9.9 kg (11 to 22 lb)15.1%487
- 10 to 24.9 kg (22 to 55 lb)23.2%748
- 25 to 44.9 kg (55 to 99 lb)40.1%1,292
- 45 kg and over (99 lb and over)9.5%305
- Weight not given6.1%195
Breed, where the report gives one breed
- Labrador Retriever9.3%300
- Golden Retriever7.1%227
- Beagle2.9%92
- Boxer2.6%83
- Chihuahua1.6%53
- Pomeranian1.6%52
- German Shepherd Dog1.5%47
- American Cocker Spaniel1.4%44
A breed with many animals has many reports.
Route in the report
- Oral70%2,252
- Ophthalmic0.1%2
- Otherunder 0.1%1
Each bar is on a scale of 0 to 100%.
Approved animal drugs with this active ingredient (FDA Green Book)
This section is reference data. It has no report count.
The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.
Brand names
- Thyro-Tabs Canine
- ThyroKare
What the Green Book records give
- Applications with an approval in force
- 2
- Approved species
- Dogs
- Dose forms
- Tablet
- Routes
- Oral
- Sale
- RX (prescription)
- Earliest approval date in the records
The species, dose forms and routes are the words of the Green Book records for all the applications together. One product can have fewer. The label of a product gives its approved use.
| Brand name | Active ingredients | Sponsor | Approved species | Application |
|---|---|---|---|---|
| Thyro-Tabs Canine | Levothyroxine sodium | Lloyd, Inc. | Dogs | NADA 141-448 |
| ThyroKare | Levothyroxine sodium | Neogen Corp. | Dogs | NADA 141-539 |
Next in the A to Z list
FDA pages for this drug
- How to Report Animal Drug and Device Side Effects and Product ProblemsThe FDA page that tells an owner or a veterinarian how to send a report.
- Green Book record of NADA 141-448The FDA record of the application for Thyro-Tabs Canine.
- Green Book record of NADA 141-539The FDA record of the application for ThyroKare.
- Animal Drugs @ FDAThe search page of the Green Book, the FDA list of approved animal drugs.
The site checked these addresses on . The links open in a new tab.
Cite this page
Pet Drug Reports. Levothyroxine sodium: adverse event reports that FDA received. https://petdrugreports.com/drug/levothyroxine-sodium/ Source: FDA Center for Veterinary Medicine, openFDA Animal and Veterinary adverse event reports, export of . Reports received through .
Where the data come from
The counts come from the openFDA Animal and Veterinary adverse event files, export of 30 Oct 2026. The files have the reports that the FDA Center for Veterinary Medicine received through 26 Jun 2026. The files mask brand and manufacturer names. The site counts a drug by the active ingredients that each record gives, and gives no count to a brand, an application or a company. Ingredient names and the lists of approved products follow the FDA Green Book of 2 Nov 2026. The site does not use the application number that a record has.
The site does not publish report text, lot numbers or details of a reporter. FDA's record is the authority. See how the site counts reports, the data sources and the corrections page.
Questions about these reports
- Which brand are these reports about?
The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand. The Green Book section of this page lists the brand names with this active ingredient.
- Do the reports show that the drug caused the signs?
No. FDA states this about the data.
When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event.
The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.
FDA Center for Veterinary Medicine. Source: Adverse Event Reports for Animal Drugs and Devices
- How many reports did FDA receive in the latest 12 months?
FDA received 254 reports in the 12 months to June 2026. It received 294 reports in the 12 months before. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.
- What kinds of report are in the count?
Of the 3,218 reports received from June 1998 to June 2026, 80.7% are about a safety issue only. 14.2% are about a lack of expected effectiveness, alone or with a safety issue. 5.1% are about a defect of the product or its package.