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Eltroxin (Levothyroxine Sodium)

Written by Dr. Feargus McConnell, BVSc on the Jan.16, 2024

Petdirect is dedicated to providing educational pet health content for pet parents. This article was written and reviewed by veterinary professionals to answer common questions about your pet’s medication. Our focus is on delivering unbiased information to help you understand how medication works, its potential side effects, and FAQs for your reference. Always administer medication directly as prescribed by your vet. This article shouldn’t take the place of advice from your vet.

What is Eltroxin?

Eltroxin, an oral medication containing levothyroxine sodium, is primarily used to treat hypothyroidism in dogs, a condition caused by the underproduction of thyroid hormones due to inflammation or degeneration of the thyroid glands. In dogs, this condition is most frequently seen in middle-aged, medium-to-large breeds. Additionally, Eltroxin can be used off-label for cats, particularly when hyperthyroidism treatments result in acquired hypothyroidism.

How does it work?

Levothyroxine is a synthetic form of the naturally occurring thyroid hormone, thyroxine, which is vital for regulating metabolism and various physiological processes. In pets with hypothyroidism, the thyroid gland fails to produce sufficient thyroxine, leading to several health issues. Administering levothyroxine helps replace the missing hormone, thus normalising the thyroid hormone levels in your pet's body.

Dose and Administration

The administration of Eltroxin should be strictly as per the veterinarian's prescription. Preferably this medication should be given at the same time each day. The dosage depends on the dog's weight and severity of their condition which will be determined by your veterinarian.

Overdose:

Large overdoses of Eltroxin can lead to serious symptoms such as agitation, seizures, and elevated heart rate. Immediately contact your veterinarian or the New Zealand National Poisons Centre at www.poisons.co.nz/animal-helpline/ or phone number 0800 869 738.

Contraindications and Precautions

Eltroxin should not be used in pets with certain heart issues, untreated Addison’s disease, or hyperthyroidism.

Potential Side Effects

While most pets tolerate Eltroxin well, some experience side effects such as:

  • Loss of appetite
  • Hyperactivity
  • Weight loss
  • Skin irritation or itching
  • Vomiting
  • Lethargy
  • Diarrhoea
  • Increased thirst
  • Increased respiratory rate

Storage

Store Eltroxin at a controlled room temperature, avoiding direct sunlight and moisture. Ensure the container is tightly closed and out of reach of children and other pets.

Monitoring

Regular monitoring of thyroid levels may be recommended by your veterinarian, especially when initiating or adjusting the dosage.  

Frequently Asked Questions (FAQ)

How long does it take for Eltroxin to show results in pets?

  • This can differ among individual pets, however typically, some pets can show improvement within the first 1-2 weeks. However, changes in weight, hair coat quality, and neurological signs may take 8-12 weeks for notable improvements.

Can Eltroxin be used for both cats and dogs?

  • While primarily used for dogs, in some cases, it may be prescribed for cats “off-label” by a veterinarian for certain thyroid conditions.

What should I do if I miss giving a dose to my pet?

  • Consult your veterinarian for guidance. Generally, you should give the missed dose as soon as you remember, or skip it if it's nearly time for the next dose. Avoid double dosing.

Are there any special considerations while using Eltroxin?

  • Consistent timing for administering the medication and adherence to the prescribed dosage are important. Also, ensure other pets do not have access to the medicated pet's faeces.

Conclusion

We hope this article provides a clear understanding of Eltroxin for your pet. Remember, always seek advice from your veterinarian for any health-related decisions for your pets.