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LEVOTHYROXINE

(For veterinary information only)

IMPORTANT NOTE: Tell the veterinarian that your pet is on this medication before any surgery.

As with all medications, it is extremely important that this medication be used ONLY for the pet for which it is prescribed.

BRAND NAME:  THYRO-TABS®

HOW THIS MEDICATION IS USED

Levothyroxine is used in the treatment of congenital (inherited) hypothyroidism and adult-onset hypothyroidism.  Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormone.

SIDE EFFECTS

If given at the prescribed dosage there are frequently no side effects.

Possible side effects may include diarrhea, weight loss, and/or change in appetite.

This medication may rarely cause chest pain upon exercise, usually only in pets with underlying heart disease. Tell your veterinarian if your pet appears uncomfortable after running or is reluctant to run (unrelated to arthritis or other health concerns).

INTERACTIONS WITH OTHER DRUGS

Tell your veterinarian if your pet is on:

• antacids or vitamins that contain aluminum, magnesium, or iron (Take them 2 to 3 hours before or after you take this medicine.)
• antihistamines, decongestants such as pseudoephedrine, and diet medications
• blood thinners as warfarin 
• digitalis, digoxin (Lanoxin®)
• estrogens
• insulin and oral medications for diabetes
• medicines for seizures such as carbamazepine, phenobarbital, and phenytoin (Dilantin®)

Levothyroxine increases effects of epinephrine, norepinephrine, and warfarin.  It may decrease the effect of digoxin.

Levothyroxine may increase insulin needs in diabetic patients.

Estrogens may increase the need for levothyroxine.

Ketamine may cause an increased heart rate and high blood pressure in animals taking thyroxine.

CONCERNS AND CAUTIONS

 Before giving this medication, tell your veterinarian if your pet has:

• adrenal gland problems
• diabetes
• heart disease
• high blood pressure

Give this medication exactly as directed by your pet’s veterinarian. Do not give more or less of it. Do not stop giving this medication without your veterinarian’s approval.

It is best to give this medication on an empty stomach, 30 minutes before your pet eats or 2 hours after your pet eats.

Do not miss a dose. If you miss a dose, give it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and give the next one as directed. Do not give double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your pet’s veterinarian.

Levothyroxine is not to be used in animals hypersensitive (allergic) to it.

Levothyroxine is not to be used in pets with heart disease, high blood pressure, or untreated Addison's disease.

Levothyroxine may be safe to use in pregnancy and nursing, but no studies confirm this, so it is best avoided if possible.

Thyroxine (T4) levels are usually measured every 2-4 weeks while adjusting dose, and are rechecked every 6 months after that.

Keep all medicines out of the reach of children.

If you have any questions, please feel free to call us at 672-7800.

Disclaimer: While Camrose Animal Clinic has endeavoured to make sure the information contained in this document is accurate, The Camrose Animal Clinic cannot guarantee the accuracy of such information, and it is provided without warranty or guarantee of any kind.  This information is not intended to replace the advice of your pet’s own veterinarian.  .  This advisory includes selected information only and may not include all side effects of this medication or interactions with other medications. Ask your veterinarian or pharmacist for more information or if you have any questions.

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