Thyroxine Sodium 25 mg for Cat
Hypothyroidism occurs when the thyroid gland fails to produce sufficient thyroid hormones. Although less common in cats than hyperthyroidism, it may develop:
- After thyroid surgery
- Following radioactive iodine therapy
- Due to autoimmune thyroiditis
- From congenital thyroid dysfunction
Untreated hypothyroidism can lead to lethargy, weight gain, skin issues, and metabolic slowdown. Thyroxine Sodium (Levothyroxine) provides a synthetic version of T4 hormone to restore normal thyroid balance.
How It Works
- Supplies synthetic Levothyroxine (T4)
- Converted in the body to T3, the active hormone
- Regulates metabolism
- Supports heart rate and thermoregulation
- Improves protein synthesis and energy utilization
Most cats show improvement within 2–6 weeks of proper dosing.
Indications
Thyroxine Sodium 25 mcg Tablets are indicated for:
- Primary hypothyroidism
- Post-thyroidectomy hormone replacement
- Iatrogenic hypothyroidism (after hyperthyroid treatment)
- Selected cases of secondary hypothyroidism
Not intended for untreated hyperthyroid cats.
Dosage Guidelines
⚠ Dosage must always be confirmed by a veterinarian based on blood T4 levels.
Standard Starting Dose:
0.05–0.1 mg/kg per day (50–100 mcg/kg daily)
Weight-Based Dosage Table
| Body Weight | Approximate Tablet Dose | Frequency |
| 1–2 kg | ¼ – ½ tablet | Once daily or divided |
| 2–4 kg | ½ – 1 tablet | Once daily or divided |
| 4–6 kg | 1 – 1.5 tablets | Once daily or divided |
| 6–8 kg | 1.5 – 2 tablets | Once daily |
| 8–10 kg | 2 – 2.5 tablets | Once daily |
✔ Blood tests required every 4–6 weeks during initial adjustment.
Administration Instructions
- Administer at the same time daily
- Give on an empty stomach if possible (30–60 minutes before food)
- Tablets may be split if required
- Avoid giving simultaneously with calcium, iron, or soy-based supplements
Consistency is critical for maintaining stable hormone levels.
Expected Improvements
With proper dosing, you may observe:
- Increased energy
- Reduced lethargy
- Improved coat quality
- Normalized weight
- Better thermoregulation
- Improved muscle tone
Most improvements appear within 3–4 weeks.
Possible Side Effects
Thyroxine is generally well-tolerated, but excessive dosing may cause hyperthyroid-like symptoms.
Mild Side Effects:
- Increased thirst
- Increased urination
- Appetite changes
- Restlessness
Signs of Overdose:
- Rapid heart rate
- Weight loss despite appetite
- Hyperactivity
- Tremors
- Panting
If these occur, contact your veterinarian immediately.
Safety Considerations
- Regular T4 blood monitoring required
- Do not abruptly stop medication
- Use caution in cats with heart disease
- Adjust dose carefully in senior cats
- Lifelong therapy is often required
Never adjust dosage without veterinary guidance.
Clinical Support
Veterinary endocrinology studies confirm:
- Levothyroxine effectively normalizes serum T4 levels
- Significant improvement in energy and coat within 4–6 weeks
- Long-term therapy is safe with proper monitoring
- Once-daily dosing is typically sufficient
Thyroxine replacement remains the gold standard therapy for feline hypothyroidism.
FAQ
Is treatment lifelong?
Yes, in most confirmed hypothyroid cases.
How often should blood work be done?
Initially every 4–6 weeks, then every 6–12 months once stable.
Can it be given with food?
Yes, but consistency is important—give the same way each day.







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