Levothyroxine For Dogs: Uses, Dosage, And Side Effects

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Levothyroxine is the active ingredient in many medications for dogs that treat hypothyroidism, a condition where the thyroid does not produce enough thyroxine, which is a hormone that controls metabolism. Levothyroxine is a synthetic version of the hormone that dogs’ bodies produce naturally in the thyroid gland. It is found in medications such as Thyro-Tabs, Soloxine, and Levocrine. Levothyroxine is FDA approved for use in dogs and is only available through a veterinary prescription. It is important to stick to your veterinarians guidelines, as overdose can lead to serious side effects. Here is what you should know about the uses, dosage, and side effects of levothyroxine for dogs.

Uses Of Levothyroxine For Dogs

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Levothyroxine is used to replace depleted thyroxine hormone levels in dogs that have hypothyroidism or other thyroid conditions. Thyroxine is an important hormone, as it regulates metabolism in dogs’ bodies. When thyroxine levels are insufficient, the body can’t convert food into fuel. This causes symptoms such as weight gain, lethargy, skin infections, poor coat health, and excessive thirst or urination.

Dosage Of Levothyroxine For Dogs

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The usual initial dosage of levothyroxine prescribed to dogs is 0.1 mg for every 10 pounds of body weight given twice a day. The medication usually comes in a chewable tablet form for dogs. If your dog is prescribed levothyroxine, your veterinarian will monitor your dog’s blood work to make sure that hormones are properly balanced. Dogs that have hypothyroidism are often prescribed levothyroxine as treatment for the rest of their lives.

A change in your dog’s symptoms may not be noticeable right away, but you should continue the regimen as your veterinarian has prescribed. It may take up to a few weeks for symptoms of hypothyroidism to improve.

Side Effects Of Levothyroxine For Dogs

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The good news is that there are no known side effects of levothyroxine for dogs if the medication is given in the proper dosage. Overdose, however, can cause the opposite of hypothyroidism, which is hyperthyroidism–a condition where there is too much of the thyroxine hormone in the blood. If you see any of the following side effects in your dog, it could mean they are suffering from an overdose and need their dosage adjusted.

  • Increased appetite
  • Increased thirst and urination
  • Decreased tolerance to heat
  • Excitability and other personality changes
  • Dizziness
  • Fainting

If you see the signs of an overdose, contact your veterinarian right away. Reducing the dosage tends to clear the side effects without further complications. Levothyroxine may not be appropriate for dogs that are pregnant or nursing. Your veterinarian should also be aware of any other medical conditions your dog has, especially heart disease, high blood pressure, or other conditions that may be affected by changes in metabolism. You should also inform your veterinarian of any other medications your dog is taking, as these may interact poorly with levothyroxine or become less effective, especially if your dog is taking medication for diabetes or Addison’s disease. As with all medications, there is a risk of allergic reaction that could lead to anaphylaxis. Contact your vet immediately if you see signs of an allergic reaction.

Has your dog ever taken levothyroxine? Did it help with they symptoms of hypothyroidism? Let us know in the comments below!