Canine thyroid disease
Canine Thyroid Disease Symptoms
The following behaviours could signal the presence of canine hypothyroidism:
Moodiness, aggression, erratic temperament, hyperactivity, lack of concentration, depression, mental dullness, lethargy, fearfulness, anxiety, submissiveness, passivity, compulsiveness, and irritability.
The following physical symptoms can also be indicative of thyroid disease:
Weight gain, increase in appetite, dry skin, hair loss/excessive shedding, ‘rat tail’, cold intolerance (seeking out warm places to lie), slow heart rate, chronic ear infections, skin infections, itching, decreased exercise tolerance/a lack of desire to exercise, seizures, reproductive problems, thickening of the skin (for example on the elbows), lameness, and dragging of feet.
What is Hypothyroidism?
Hypothyroidism is a disorder of the thyroid gland, which consists of two small butterfly-shaped lobes in the neck that lie along the windpipe (trachea) and are joined together by a narrow band of thyroid tissue.
The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones called thyroxine (T4) and triiodothyronine (T3). Thyroid cells are the only cells in the body which can absorb iodine. These cells combine iodine and the amino acid tyrosine to make T3 and T4.
T3 and T4 are then released into the bloodstream and are transported around the body where they control metabolism (conversion of oxygen and calories to energy). Every cell in the body depends upon thyroid hormones for regulation of its metabolism. In hypothyroidism, the most common thyroid disease in dogs, the thyroid gland is under-active, and unable to secrete enough thyroid hormone.
The causes of thyroid disease
The following behaviours could signal the presence of canine hypothyroidism:
Moodiness, aggression, erratic temperament, hyperactivity, lack of concentration, depression, mental dullness, lethargy, fearfulness, anxiety, submissiveness, passivity, compulsiveness, and irritability.
The following physical symptoms can also be indicative of thyroid disease:
Weight gain, increase in appetite, dry skin, hair loss/excessive shedding, ‘rat tail’, cold intolerance (seeking out warm places to lie), slow heart rate, chronic ear infections, skin infections, itching, decreased exercise tolerance/a lack of desire to exercise, seizures, reproductive problems, thickening of the skin (for example on the elbows), lameness, and dragging of feet.
What is Hypothyroidism?
Hypothyroidism is a disorder of the thyroid gland, which consists of two small butterfly-shaped lobes in the neck that lie along the windpipe (trachea) and are joined together by a narrow band of thyroid tissue.
The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones called thyroxine (T4) and triiodothyronine (T3). Thyroid cells are the only cells in the body which can absorb iodine. These cells combine iodine and the amino acid tyrosine to make T3 and T4.
T3 and T4 are then released into the bloodstream and are transported around the body where they control metabolism (conversion of oxygen and calories to energy). Every cell in the body depends upon thyroid hormones for regulation of its metabolism. In hypothyroidism, the most common thyroid disease in dogs, the thyroid gland is under-active, and unable to secrete enough thyroid hormone.
The causes of thyroid disease
- Autoimmunity The majority of cases of hypothyroidism arise when the dog’s own immune system attacks tissues of the thyroid gland. This is called autoimmune thyroiditis.
The dog’s own system attempts to compensate for this autoimmunity by secreting more and more of the thyroid hormone, but eventually the gland is unable to keep up with the attacks on its tissue, and the dog becomes hypothyroid and develops some of the symptoms shown above.
- Genes There is a genetic predisposition for thyroid disorders, with the following breeds most prevalent in the statistics:
Golden Retrievers
Doberman Pinschers
Irish Setters
English Setter
Dachshunds
Cocker Spaniels
Boxers
Shetland Sheepdogs
Dogs who are known to be hypothyroid should not be bred from.
- Environmental Some environmental factors such as pollutants and allergies are thought to play a role in thyroid disease.
For example, fluoride found in drinking water is a known thyroid inhibitor. Artificial fluoride is most often fluorosilicic acid, which is captured from the chimney stacks of the phosphate fertiliser industry. In essence it is a protoplasmic poison which is more toxic than lead.
It is possible that, by filtering fluoride from drinking water, or giving non-fluoridated water, the symptoms of thyroid disease in your dog can be alleviated or removed.
Vaccines are also known to stimulate autoimmunity and, according to Jean W Dodds, vaccines can cause hypothyroidism, which then gets passed down the line. (Thyroid disease is inheritable.)
Some flea control products are known to affect the thyroid in laboratory animals. Fipronil, found in Frontline, has been shown to cause thyroid cancer and altered thyroid hormones. Imidacloprid, used in Advantage, shows evidence of causing thyroid lesions in dogs.
Allergies (which, as stated earlier, can be behind thyroid disease) arise from a combination of genetic predisposition and environmental triggers. Allergic conditions are symptomatic of underlying B and T cell immunodeficiencies. For example, inhalant allergies, food allergies, dermatitis, eczema, heart disease, and neurological deterioration are features of B and/or T cell immunodeficiencies. Vaccines are known to cause T cell immunodeficiencies, and B and T cell immunodeficiencies are inheritable. The Merck Manual (produced by Merck, a vaccine manufacturer) advises that patients with B and/or T cell immunodeficiencies should not receive live virus vaccines.
- Dietary imbalances Dietary imbalances can also lie behind an under-functioning thyroid, either because individuals don’t eat the foods that contain iodine in sufficient quantities, or because modern farming methods are robbing foods of this nutrient.
Concentrated food sources of iodine include sea vegetables, yogurt, cow’s milk eggs, strawberries and mozzarella cheese. Fish and shellfish can also be concentrated sources of iodine. It can also be found in plant foods such as cereals and grains, but the levels vary depending on the amount of iodine in the soil where the plants are grown.
Selenium deficiency can increase the effects of iodine deficiency, as selenium-dependent enzymes are also required for the conversion of T4 to T3. Vitamin A and iron deficiencies may also increase the effects of iodine deficiency.
The absorption and/or utilization of iodine is also inhibited by components of certain foods. These food components, called goitrogenic compounds, are found primarily in cruciferous vegetables (for example, cabbage and broccoli), soybean products, peanuts, mustard, and millet.
Over consumption of these foods may lead to thyroid problems by reducing the amount of available iodine for the manufacture of thyroid hormones. It is believed that cooking can inactivate the goitrogenic compounds in these foods, thereby eliminating their negative impact on iodine status. Natural feeders might limit these foods, and/or to steam them rather than give processed (highly mashed) raw vegetables.
Seaweed, or kelp, is a useful source of natural minerals for dogs, particularly sodium, potassium, calcium and iodine.
Diagnosis
Because hypothyroidism can easily be mistaken for behavioural problems or other diseases, it frequently goes undiagnosed. Further, the bloodwork results aren’t always accurate.
In the human field, specialists are treating the symptoms of thyroid disease even if blood tests indicate that the person’s thyroid is normal. One woman, for example – Diana Holmes – was misdiagnosed six times over a period of 23 years. During that time, she received toxic drugs for diseases she did not have, and eventually wound up in a wheelchair. Only when she saw a thyroid specialist and was given thyroid supplements despite the normal blood results, did she regain her health and go on to live a normal life. Her informative and helpful story is told in her book, ‘Tears Behind Closed Doors’.
Similarly, some enlightened vets will give thyroid supplements based upon symptoms. In other words, diagnosis is based upon the animal’s response to therapy.
Dr Jean W Dodds is one of the best known authorities on canine thyroid disease. She has found that many vets will perform a limited range of blood tests, which allows thyroid disease to remain undetected.
Dr Dodds says: “Because the diagnosis of hypothyroidism is often complicated, we need to run complete thyroid profiles (i.e., T3, T4, free T3, free T4, T3 and T4 auto antibodies, plus thyroglobulin auto antibody and TSH where indicated) rather than just one or two analytes (e.g., T4, TSH, free T4). We need to look at the whole picture along with the clinical history, breed and family history for likelihood of thyroid disease. When I interpret profiles and make recommendations, I take all these factors, including drugs being given, into consideration.
“After 6 to 8 weeks on thyroid supplementation given twice daily, at the appropriate dose for the dog's age, breed and weight, the thyroid levels should be retested to determine whether the current dose is correct. This sample needs to be drawn 4 to 6 hours after the morning pill was given. IMPORTANT: Correct therapeutic ranges at that time should be at the upper 1/3 to 25% above the upper limits of the lab reference ranges (except for geriatric dogs or sight hounds where mid-range is adequate).”
For details of Dr Dodds’ thyroid profiling service, see www.hemopet.org/services.html
The Good News
Improvements are usually seen in the first week of therapy. This includes mental alertness, more activity, and improved muscle strength. Other improvements may take a little longer. All the signs of hypothyroidism are reversible once treatment is started. A dog with thyroid disease can go on to live long, happy, lives.
Complementary therapies
A good veterinary homoeopath may have some success in treating thyroid disease. One of my own dogs, for example, was blood tested for thyroid disease and showed greatly reduced levels. He was given a homoeopathic remedy to treat his specific symptoms and, two months later, his blood readings were exactly where they needed to be. Because the homoeopathic remedy for any disease is specific to the patient, and because thyroid disease is potentially very serious, I recommend you visit a good homoeopathic vet to treat your friend.