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Canine Hypothyroidism: Diagnosis and Treatment


Hypothyroidism is a disease of the endocrine system that occurs in both humans and dogs. It is characterized by a deficiency of thyroid hormones. Hypothyroidism, sometimes called under-active thyroid, causes a decreased metabolic rate and can lead to a variety of systemic complications.

If you suspect that your dog has hypothyroidism, you should schedule an appointment with your veterinarian. Learn about the process of diagnosing and, if necessary, treating hypothyroidism in dogs.

Diagnosing Hypothyroidism in Dogs:

By providing an accurate, thorough history to your veterinarian, you can help detect hypothyroidism in your dog. The first step in the official diagnosis of canine hypothyroidism is to test the thyroid hormone levels in the blood. In most cases, your vet will begin by testing the T4 level. In theory, a low T4 indicates hypothyroidism, but diagnosis is not always this simple. Sometimes the T4 can fall in a gray area and further testing is necessary. In addition, certain medications can interfere with the T4 levels.

Your vet may recommend other blood tests before making a definitive diagnosis. These include measurement of free T4 (the T4 circulating "freely" through the bloodstream) and TSH. Low levels of free T4 are consistent with hypothyroidism. High levels of TSH also indicate hypothyroidism because the pituitary gland will often produce excess TSH in an effort to stimulate the thyroid gland.

Not all cases of hypothyroidism cause abnormal levels in all three primary tests. Hypothyroidism is diagnosed with a combination of blood tests and patient history. Additionally, there are other diseases that cause similar symptoms, so what seems like hypothroidism at first could be a completely different issue. This is why it is important to communicate with your vet. Discuss all of your pet's symptoms and ask about your diagnostic options.

Hypothyroidism Treatments:

There is no known cure for hypothyroidism, but the disease is generally easy to manage with medication. Typically, hypothyroid dogs are prescribed synthetic thyroid hormone (T4) to be given orally one to two times daily. The drug names for these thyroid supplements are levothyroxine or L-thyroxine. Common brand names for levothyroxine and L-thyroxine are Soloxine and Thyro-Tabs, respectively. However, other brand names and generic forms are available. In rare cases, liothyronine (T3) is prescribed for dogs that are unable to convert T4 into T3.

The good news is that there are virtually no side effects associated with the usage of thyroid supplements. As with any medication, accidental overdose can occur. Symptoms of overdose include excess drinking and urinating, restlessness, panting, diarrhea and increased appetite.

Hypothyroid dogs must be treated for life. While the cost of thyroid supplements is fairly low, it does add up over time. Expect to spend about $30-60 per month on medication (depending on dosage and brand). This does not include the cost of periodic blood monitoring. Be sure to factor costs into your pet budget.

There are no herbal, homeopathic or home remedies that are effective as alternatives to synthetic thyroid hormone supplements. However, some remedies may be helpful in conjunction with thyroid supplementation. Talk to your vet about the options for your dog.

Monitoring the Hypothyroid Dog:

As the owner of a hypothyroid dog, your job is to do your best to keep his disease under control. Your vet will recommend routine blood work to check thyroid levels. When treatment first begins, blood tests will be needed every few weeks until the disease is under control. Once the hypothyroidism appears to be regulated, most vets recommend checking thyroid levels every six months (possibly every year if your dog has done well long-term). Over time, it is normal for your dog's prescribed dose to change. When the dosage is adjusted, blood levels may need be checked more often at first.

Be sure to keep track of changes in your dog's health, appearance or behavior. Contact your vet if you notice any signs of illness, particularly those signs associated with hypothyroidism or thyroid supplement overdose.

Fortunately, most dogs with hypothyroidism can lead long, healthy lives when properly treated and monitored. Keep your dog healthy and stay in touch with your vet about your dog's condition

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