Meds A-Z
Levothyroxine
Detailed information about Levothyroxine
Pet Owner Quick Guide
Start here: what this medicine is for, what it does, and when it's usually needed.
Usually used for:
For replacement therapy for diminished thyroid function in dogs.
What it does:
For replacement therapy for diminished thyroid function in dogs.
When it's needed:
For oral use in dogs only. Federal law restricts this drug to use by or on the order of a licensed veterinarian.
Call your vet sooner if you notice:
- For oral use in dogs only. Federal law restricts this drug to use by or on the order of a licensed veterinarian.
Commonly reported reactions:
- (1 reports)
- (1 reports)
- (1 reports)
What to ask your vet today:
- Is this medicine the right fit for my pet’s current symptoms?
- Which warning signs mean I should call back right away?
- How should I handle missed doses or refusal to take the medicine?
Levothyroxine
Drug type: Generic ingredient • Branded profile • FDA branded products available
Species: Both
Manufacturer: MSK
Quick Facts
Official label facts first, then secondary summaries. Marketing content is separated below.
- https://animaldrugsatfda.fda.gov/adafda/views/#/home/previewsearch/141539 · official_label · FDA application profile
- https://animaldrugsatfda.fda.gov/adafda/views/#/home/previewsearch/141448 · official_label · FDA application profile
- https://animaldrugsatfda.fda.gov · fda_animal_drugs · Medication usage source
Warnings / Contraindications
For oral use in dogs only. Federal law restricts this drug to use by or on the order of a licensed veterinarian.
- High: For oral use in dogs only. Federal law restricts this drug to use by or on the order of a licensed veterinarian.
- https://animaldrugsatfda.fda.gov · fda_animal_drugs · Contraindication source
Adverse Reactions
Snapshot first, detailed rows second. This section summarizes signal data and is not a diagnosis.
Tap or hover a reaction to see what it means in plain language.
Most Reported Reactions
| Reaction | Cases | Species | Serious cases |
|---|---|---|---|
| 1 | Cat | 1 | |
| 1 | Cat | 1 | |
| 1 | Cat | 1 | |
| 1 | Dog | 1 | |
| 1 | Dog | 1 | |
| 1 | Cat | 1 | |
| 1 | Cat | 1 | |
| 1 | Dog | 1 |
Species coverage: Dog (18) Cat (14)
View detailed reaction table
| Reaction | Species | Seriousness | Frequency | Reports |
|---|---|---|---|---|
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Cat | Non-serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Non-serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Cat | Serious | - | 1 |
- https://api.fda.gov/animalandveterinary/event.json · adverse_reaction · openFDA case USA-USFDACVM-2025-US-034962
Storage & Handling
No storage/handling guidance is linked yet.
Documents
Official label facts are separated from secondary summaries.
Official documents: 4 • Secondary summaries: 0
- FOI Summary oN 141-539 Approved January 15, 2021.pdf · FOI
- ThyroKare™ · SPL
- UCM484490.pdf · FOI
- Thyro-Tabs® Canine · SPL
No source yet.
- https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadFoi/10310 · document · FOI
- https://animaldrugsatfda.fda.gov/adafda/app/search/public/spl/file/10370/ThyroKare%E2%84%A2 · document · SPL
- https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadFoi/937 · document · FOI
- https://animaldrugsatfda.fda.gov/adafda/app/search/public/spl/file/2392/Thyro-Tabs%C2%AE%20Canine · document · SPL
Promotional Materials (Marketing)
This content is marketing material and not clinical guidance.
No marketing assets are linked yet.
No source yet.
Technical appendix (vet reference)
Canonical medication sections are above. This legacy block remains available for deeper cross-reference without cluttering the primary workflow.
At a Glance
Quick facts and links to official labeling and safety signals.
- Medication catalog: Source PetWisePlus | Refreshed Feb 12, 2026, 10:44 PM UTC
-
Animal Drugs @ FDA:
Source FDA
| Refreshed Feb 16, 2026, 11:00 AM UTC
Applications/products are imported from FDA export data.
-
Animal Drugs @ FDA previews:
Source FDA
| Refreshed Feb 9, 2026, 3:05 AM UTC
Label highlights/doc links are fetched from FDA preview endpoints.
-
Animal Drug Product Listing Directory (NDC):
Source FDA
| Refreshed Feb 16, 2026, 11:00 AM UTC
Package/product NDCs from FDA’s electronic listing directory (XLS).
- openFDA reaction terms: Source FDA openFDA | Refreshed Feb 16, 2026, 11:04 AM UTC
- openFDA case summaries: Source FDA openFDA | Refreshed Feb 9, 2026, 3:21 AM UTC
Diagnosis-code mappings are not available for this medication yet.
Counseling and Monitoring Highlights
Global Pet owner/Vet mode is controlled in the header. This section avoids duplicate in-page persona tabs.
- For oral use in dogs only. Federal law restricts this drug to use by or on the order of a licensed veterinarian. (Contraindication, High)
Identifiers & Packages
Normalized identifiers (NDC/NADA/ANADA) and package metadata from regulator listings.
| Package NDC | Product NDC | Form / Route | Status |
|---|---|---|---|
| 11695-6957-1 | 11695 | - | |
| 11695-6957-2 | 11695 | - | |
| 11695-6958-1 | 11695 | - | |
| 11695-6958-2 | 11695 | - | |
| 11695-6959-1 | 11695 | - | |
| 11695-6959-2 | 11695 | - | |
| 11695-6960-1 | 11695 | - | |
| 11695-6960-2 | 11695 | - | |
| 11695-6961-1 | 11695 | - | |
| 11695-6961-2 | 11695 | - | |
| 11695-6962-1 | 11695 | - | |
| 11695-6962-2 | 11695 | - | |
| 11695-6963-1 | 11695 | - | |
| 11695-6963-2 | 11695 | - | |
| 11695-6964-1 | 11695 | - | |
| 11695-6964-2 | 11695 | - | |
| 11695-6965-1 | 11695 | - | |
| 11695-6965-2 | 11695 | - | |
| 11695-7014-1 | 11695 | - | |
| 11695-7014-2 | 11695 | - |
Enriched Documents
Documents are tiered by source trust: Official, Clinical, Manufacturer, Marketing.
-
FOI Summary oN 141-539 Approved January 15, 2021.pdf
• FOI summary • Official
• Feb. 1, 2021
FDA FOI summary for application 141539
-
UCM484490.pdf
• FOI summary • Official
• June 1, 2016
FDA FOI summary for application 141448
Data Sources & Revision History
Every non-trivial field is expected to include provenance and update timestamps.
- contraindications: For oral use in dogs only. Federal law restricts this drug to use by or on the order of a licensed veterinarian. (Official, 2026-02-12)
- side_effects: Top reported reactions (openFDA): Vomiting, Diarrhoea, Lethargy (see also Central nervous system depression in 'Neurological'), Death by euthanasia, Lack of ef… (Official, 2026-02-12)
- usage: For replacement therapy for diminished thyroid function in dogs. (Official, 2026-02-12)
- side_effects updated 2026-02-12 22:44 by etl_backfill • Backfilled from existing medication fields
- contraindications updated 2026-02-12 22:44 by etl_backfill • Backfilled from existing medication fields
- usage updated 2026-02-12 22:44 by etl_backfill • Backfilled from existing medication fields
FDA Products & Applications (Animal Drugs @ FDA)
Official sponsor/proprietary-name/application-status records linked by active ingredient.
| Product | Sponsor | Application | Status | Published |
|---|---|---|---|---|
|
ThyroKare™
RX
Levothyroxine sodium
Tablet
• Oral
|
Neogen Corp. | NADA 141-539 | Approved | Feb 1, 2021 |
|
Thyro-Tabs® Canine
RX
Levothyroxine sodium
Tablet
• Oral
|
Lloyd, Inc. | NADA 141-448 | Approved | Jun 1, 2016 |
Data source: FDA Animal Drugs @ FDA (public search export).
What It's For (FDA Label Highlights)
Extracted from FDA Animal Drugs @ FDA product labeling. Always confirm details with your veterinarian.
Composition / specifications
For replacement therapy for diminished thyroid function in dogs.
The initial dose is 0.1 mg/10 lb (0.01 mg/lb, 0.022 mg/kg) body weight twice daily.
FDA page: Open in Animal Drugs @ FDA
Composition / specifications
FDA page: Open in Animal Drugs @ FDA
Official Documents (FDA)
Direct links to FDA-hosted PDFs and SPL packages (when available).
-
Summary
For replacement therapy for diminished thyroid function in dogs.
- ThyroKare™ (ZIP)
FDA page: Open in Animal Drugs @ FDA
-
FOI UCM484490.pdf
Summary
For replacement therapy for diminished thyroid function in dogs.
- Thyro-Tabs® Canine (ZIP)
FDA page: Open in Animal Drugs @ FDA
Usage
For replacement therapy for diminished thyroid function in dogs.
Source: FDA Animal Drugs @ FDA • Reference
Contraindications
For oral use in dogs only. Federal law restricts this drug to use by or on the order of a licensed veterinarian.
Side Effects
No approved side-effect narrative is linked yet.
openFDA reaction signals are available for Dog 56 and Cat 8 (view top reported reactions).
Top Reported Reactions (openFDA)
Aggregated reaction terms from FDA openFDA reports (not verified; does not prove causation).
Data source: FDA openFDA Animal & Veterinary adverse event reports.
Adverse Event Case Summaries (openFDA)
These are individual FDA adverse event reports. They are unverified and do not prove the medication caused the reaction.
Dog, Mastiff (unspecified), Male, 5.5 year, 90.26 kilogram • Drug: MSK, Unknown • Reactions: Regenerative anaemia, Tiredness (lethargy), Localised oedema, Uncomfortable, Lack of efficacy - NOS… • Outcome: Ongoing
- Report ID: USA-USFDACVM-2025-US-054417
- Serious AE: No
- Treated For AE: Yes
- Sex: Male
- Age: 5.50 Year
- Weight: 90.260 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
Dog, Chihuahua, Female, 12 year, 8.16 kilogram • Drug: MSK, Unknown • Reactions: Tarry or black stool • Outcome: Recovered/Normal
- Report ID: USA-USFDACVM-2025-US-054372
- Serious AE: No
- Treated For AE: No
- Sex: Female
- Age: 12.00 Year
- Weight: 8.160 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
Dog, Terrier - Jack Russell, Male, 12 year, 8.5 kilogram • Drug: MSK, Tablet, Oral • Reactions: Leucopenia NOS, Loss of appetite, Anaemia NOS, Pancytopenia, Hepatomegaly… • Outcome: Outcome Unknown
- Report ID: USA-USFDACVM-2025-US-055620
- Serious AE: Yes
- Treated For AE: Yes
- Sex: Male
- Age: 12.00 Year
- Weight: 8.500 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Oral
- Form: Tablet
Dog, ['Retriever - Labrador', 'Poodle (unspecified)'], Male, 4 year, 27.44 kilogram • Drug: MSK, Unknown • Reactions: Wobbliness, Shaking • Outcome: Outcome Unknown
- Report ID: USA-USFDACVM-2025-US-054472
- Serious AE: No
- Treated For AE: No
- Sex: Male
- Age: 4.00 Year
- Weight: 27.440 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
Dog, Terrier - American Staffordshire, Male, 12 year, 33.11 kilogram • Drug: MSK, Unknown • Reactions: Diarrhea, Bloody diarrhoea • Outcome: Recovered/Normal
- Report ID: USA-USFDACVM-2025-US-053304
- Serious AE: No
- Treated For AE: Yes
- Sex: Male
- Age: 12.00 Year
- Weight: 33.110 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
Cat, Cat (unknown), Female, 15 year, 3.57 kilogram • Drug: MSK, Tablet, Oral • Reactions: Vomiting, Acute renal failure, Elevated symmetrical dimethylarginine, Elevated creatinine, Decreased urine concentration… • Outcome: Outcome Unknown
- Report ID: USA-USFDACVM-2025-US-034962
- Serious AE: Yes
- Treated For AE: No
- Sex: Female
- Age: 15.00 Year
- Weight: 3.570 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Oral
- Form: Tablet
Cat, Domestic Longhair, Female, 15 year, 3.57 kilogram • Drug: MSK, Unassigned, Unknown • Reactions: Vomiting, Acute renal failure, Elevated symmetrical dimethylarginine, Elevated creatinine, Decreased urine concentration… • Outcome: Ongoing
- Report ID: USA-USFDACVM-2025-US-026652
- Serious AE: Yes
- Treated For AE: Yes
- Sex: Female
- Age: 15.00 Year
- Weight: 3.570 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
- Form: Unassigned
Cat, Domestic Shorthair, Male, 16 year, 4.62 kilogram • Drug: MSK, Unknown • Reactions: No sign, Product compounding error
- Report ID: USA-USFDACVM-2025-US-025802
- Serious AE: No
- Treated For AE: No
- Sex: Male
- Age: 16.00 Year
- Weight: 4.620 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
Data source: FDA openFDA Animal & Veterinary adverse event reports.
Overdose Information
No approved overdose-management text is linked yet. If overdose is suspected, contact a veterinarian or emergency clinic immediately.
Storage & Handling
No approved storage guidance is linked yet for this ingredient. Use manufacturer packaging and veterinary guidance for handling/storage.
Share Your Thoughts
Let others know your experience or advice regarding this medication.
This medication has not been reviewed by a veterinarian yet.