The information provided on this web site is for informational purposes only. At no time should any information found on this web site replace the advice of your veterinarian. You should refer to your veterinarian before giving any dosage for the medication listed. Whenever in doubt, seek advice from your veterinarian.

    The thyroid gland is responsible for producing and secreting thyroid hormone (thyroxine), which affects nearly all body systems. Thyroxine is the hormone that is primarily responsible for regulating the metabolic rate of many different tissues in the body. When hypothyroidism occurs, the amount of thyroxine produced is below the required amount needed which causes the metabolism within the tissues to slow down.

Hypothyroidism is the most common hormonal disorder in dogs. It's usually found between the ages of 4 and 10. Hypothyroidism is found more often in neutered males and spayed females however it's not uncommon for non-neutered or non-spayed dogs to come down with thyroid problems.

Causes for Hypothyroidism

• Inflammation of the thyroid gland due to the immune system attacking the gland by mistake (Lymphocytic Thyroiditis).
• Degeneration of the thyroid glad without evidence of inflammation (Idiopathic Follicular Atrophy). The cause of this condition is unknown.
• Neoplasia (Thyroid tumors), although not a common cause for hypothyroidism it has been found. For a tumor to affect the hormone output, it would have to attach both lobes of the thyroid and thoroughly destroy the gland.
• Radiation therapy or radioactive iodine treatments.
• Surgical removal of the thyroid gland (thyroidectomy). Thyroidectomy is usually performed to remove a thyroid tumor.
• Dietary iodine deficiency, although not common. Most commercial dog foods contain adequate levels of iodine.
• Disease of the pituitary gland may result in a deficiency of thyroid stimulating hormone
• The use of some medications containing sulfa (usually antibiotics). This form of hypothyroidism may go undetected because the gland may recover once the drug is no longer used.

What to watch for

    Although there is no one symptom that usually indicates hypothyroidism a combination of  the following symptoms could indicate an issue.

• Chronic skin disorders (dry skin, excessive hair lose, thinning of the hair)
• Diarrhea
• Lethargy (increase in sleep, lack of interest to play)
• Depression
• Tires easily
• Constipation
• Weight gain and obesity (without increase in appetite)
• Low body temperature
• Slow heart rate
• Infertility
• Possible other hormonal abnormalities
• More aggressive (usually in mild cases of hypothyroidism)

Treatment

    Hypothyroidism is easily treated. It usually requires daily treatments of a synthetic thyroxine. It's important to note, once treatment starts it usually is required for the remainder of the dogs life. Failure to continue treatment could be fatal. You should never stop thyroid treatment without consulting your veterinarian first.

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