How Can My Dog Be Hypothyroid and Still Have Normal Thyroid Hormone Production?

Posted on October 9th, 2014

My clinical veterinary studies over the past 48 years have identified two different conditions that will cause a dog to show all the signs of hypothyroidism and still produce normal thyroid hormones.

The following is a list of clinical signs indicating that the dog is hypothyroid, even with the production of normal thyroid hormones:

  • Weight gain
  • Bilateral hair loss
  • Dry, brittle hair
  • Bilateral pigmentation
  • Lipomas
  • Lethargy
  • Slow heart rate
  • Chronic infections
  • Personality disorders

The first clinical condition that will cause a state of hypothyroid to occur even with the normal production of thyroid hormones, will happen because of elevated total estrogen.

The elevated total estrogen will cause a binding of the receptor sites for the two thyroid hormones referred to as T3 (triiodothyronine) and T4 (thyroxin).

When this occurs, T3 and T4 are not available for use in the body because of the estrogenic thyroid binding. In this instance, T3 and T4 will occur in normal levels.

In diagnosing a patient that appears to be hypothyroid, testing for T3, T4, free T3, free T4, and TBG (thyroid binding globulin) may not identify the problem unless a total estrogen is also included.

24 hour urine tests and salivary tests may be of value, but even with identifying active thyroid hormone, without checking total estrogen, will not indicate whether the T3 and T4 are available for use in the body.

If total estrogen is elevated in a dog with signs of hypothyroidism a T4 supplement is indicated and given twice daily. This relationship between estrogen and the thyroid gland is also realized with women.

PubMed, with an abstract by Mace ND states, “Because of its hepatic first pass effect, oral estrogen raises the circulatory levels of thyroid binding globulin TBG, thereby increasing the bound fractions T4 and decreasing the free fractions (bioactive) T3. As a consequence, taking oral estrogen in women will increase the T4 requirements for primary hypothyroidism, as well as alter the pituitary-thyroid axis in euthyroid woman. NOTE: Euthyroid is the state of having normal thyroid function”.

Hypothyroid Mom published the following statement, “Estrogen dominance causes the liver to produce high levels of TBG, which binds thyroid hormones and decreases the amount of thyroid hormone that can be assimilated and utilized by the cells”.

Healthful Elements published, “The role of estrogen in hypothyroidism is well researched. Estrogen directly effects the thyroid by thwarting its ability to produce thyroid hormone. Hot flashes, flushing, weight gain, unstable moods, brain fogs, and heavy periods are all signs of estrogen dominance. Add some hypothyroidism to this and you have thyropause”.

Healthful Elements has also identified other ways of causing estrogen dominance:
  • Xenoestrogens (plastics)
  • Synthetic estrogen (medications)
  • Environmental toxins (estrogen mimickers)

My own clinical studies have also found that estrogen dominance, can be created by the inner layer adrenal cortex, referred to as the zona reticularis. This is a very important finding for humans and for animals. The significance is not realized just yet.

Adrenal estrogen must be included in the measurements of total estrogen, otherwise hypothyroidism and allergy, autoimmunity and cancer will not be treated correctly.

It is interesting that the medical profession is fearful of the diseases and inflammation excess estrogen causes, yet they are not measuring total estrogen!

In female and male animals and also in human males, only estradiol is measured, and not total estrogen.

In human females, only estradiol, estriol and estrone are measured, and total estrogen, which includes adrenal estrogen, is not measured.

The second condition that causes a state of hypothyroidism, comes from a cortisol imbalance.

Cortisol is produced every day in animals and humans from the middle layer adrenal cortex, referred to as the zona fasciculata.

When the production of cortisol is deficient or defective and inactive, the transference of inactive T4 (thyroxin) into active T3 (triiodothyronine) will not occur. When this happens, a state of hypothyroidism may exist.

The veterinary profession commonly depends only on inactive T4 levels to determine if a state of hypo or hyperthyroidism is present. This is why it is so important to measure both active T3 and inactive T4. If the inactive T4 is elevated and the active T3 is low, normal or deficient, a cortisol imbalance is present, causing this lack of transference. This lack of transference can lead to an elevated inactive T4, which may be referred to as a state of hyperthyroidism.

Unfortunately, the fact remains that the patient will still show signs of hypothyroidism.

NOTE: Felines are often diagnosed as being hyperthyroid with only an elevated T4, without also checking the T3 level. A diagnosis of hyperthyroidism should never be made without a T3 level, since the problem may be due to a cortisol transference imbalance and not due to a state of hyperthyroidism!

The Health and Wellness Center reports on the Thyroid-Cortisol Connection:

“Cortisol acts in synergy with the thyroid hormones and makes it work efficiently. Without the necessary cortisol, patients either do not tolerate or are unable to properly convert the inactive thyroid hormone T4 into active thyroid hormone T3.”

There are other thoughts why cortisol deficiencies occur.

Stop The Thyroid Madness (STTM) has published an article titled How Adrenals Can Wreak Havoc. They state the following:

“Your stress-busting adrenals have been working hard to keep you going with extra cortisol and adrenaline. Even a poor diet and excess exposure to heavy metals and toxins could have further stressed your adrenals. After any of the above occur, your adrenal function can then move to becoming cortisol insufficient. You can have a problem in the HPA axis which is messaging between your hypothalamus, pituitary gland and adrenals and can result in the adrenals failing to respond.”

Hopefully you can realize that with elevated total estrogen and or a cortisol imbalance that normal thyroid hormones may be present, but may not be unavailable for use in the body, causing a state of hypothyroidism.

It is important that you realize when funding a cortisol imbalance in a canine and in a human that most modern cortisol supplements will last in the body for at least 24 hours. Because the cortisol imbalance causes the production of elevated total estrogen, which causes a state of hypothyroidism to occur, the metabolism of the liver and kidney will be reduced. When this happens, the cortisol replacement supplement will not be broken down and excreted in a timely manner.

Without also providing a thyroid supplement to help increase the metabolism of the liver and kidneys, a cortisol residue will remain after 24 hours. This remaining residue will cause a buildup of the cortisol supplement and in a short period of time, all the side effects of a steroid overdose will occur.

NOTE: The one exception to this rule comes with use of Cortef, which lasts only 6 hours in the body.

Cortef was used very successfully by Dr. William Mac Jefferies for many years and you can read about his experiences using Cortef in his book entitled, The Safe Uses of Cortisol. The concern with using Cortef in the world today is because of the use of corn starch as one of the inactive ingredients. There is a fear that the corn starch comes from GMO corn and also the fact, that many humans and animals may be allergic to corn and corn products.

For further information on doing the proper blood test to identify either one of these imbalances, please read Test Procedures and Info. Here you will find the Animal and Human protocols, and where the serum samples can be sent to be processed (Laboratory Information).

Hopefully this article will help you and your dog live a longer, happier and healthier life, without either one of you suffering from hypothyroidism.


Dr. AL Plechner