Hypothyroidism in dogs: symptoms, treatment, causes of the disease

One of the youngest and fastest growing branches of medicine is endocrinology. However, in veterinary practice, the diagnosis of most endocrine disorders is presently in the embryonic state. Nevertheless, the animals are sick, and the task of specialists is to diagnose correctly and, if necessary, to correct the disorders of the endocrine system.

One of the most common such diseases is hypothyroidism in dogs. Photos of animals, causes, symptoms and ways of treating this disease we will present to you in this article. Methods of diagnostics will also be considered.

Hypothyroidism in dogs: a description of the disease

This disease is accompanied by disorders in the activity of the thyroid gland, which has many different functions. Hypothyroidism is a pathology characterized by a decrease in the number of synthesized hormones of the thyroid gland.

Types of the disease

Specialists distinguish two types of this disease - primary and secondary. Acquired (primary) hypothyroidism is an inflammation of the thyroid gland, which is called Hashimoto's disease, or other processes that destroy the organ. Sometimes hypothyroidism in dogs provokes a lack of iodine in the diet of an animal, infection, a tumor of the thyroid gland. In any case, the affected organ is unable to produce the necessary amount of hormones.

Secondary hypothyroidism in dogs, the signs of which can appear at an early age of the animal, destroys the growing organism. Hormones of thyroid are necessary for the development of the central nervous system and bones, their lack can cause dwarfism of animals. Secondary hypothyroidism in dogs is manifested with congenital thyroid dysfunction or predisposition to the formation of tumors. As a result, the process of hormone production is disrupted.

Secondary hypothyroidism sometimes develops after improper treatment with glucocorticoids or with an unbalanced diet.

Stages of the disease

In the development of hypothyroidism in dogs, the symptoms are also different. At an early stage of the disease, the amount of tyrosine in the thyroid gland decreases, provoking an increased production of other hormones. Thus, the hormone balance is leveled in the body. In very rare cases, the body can recover independently, but much more often the disease passes into the late stage.

In this case, the level of tyrosine is significantly and very sharply reduced, while balancing of the balance is impossible. The thyroid gland gets serious damage, which leads to a significant deterioration in the general condition of the animal.

Like most endocrine pathologies, hypothyroidism in dogs may have different symptoms. Most often on the development of the disease indicates overweight, obesity. In addition, this disease is often diagnosed with a loss of hair and skin problems.

How is hypothyroidism diagnosed in dogs? Diagnosis is possible only in a good veterinary clinic after a complete examination of the animal's blood. The result of the analysis will allow to compare the obtained data with the norm, which is typical for animals of the same age and breed.

Causes of the disease

The thyroid gland is a small gland located in the larynx. Her work is regulated by the pituitary gland of the brain. For its normal activity, a special stimulating hormone is needed. The pituitary gland synthesizes such a hormone, and it causes the thyroid gland to intensively produce its own. On his condition depends on the performance of the gland.

However, hypothyroidism in dogs quite often develops in animals whose pituitary body is in a normal state. Why is this happening? About 95% of cases are "background", they develop due to diseases that accompany the processes of destructive changes in the thyroid gland. Unfortunately, it is not always possible to clarify the essence of these processes.

Veterinarians believe that the autoimmune disorders in which the animal's body begins to destroy itself are to blame for this. Hypothyroidism, the cause of which can be different, is often the result of thyroid atrophy. This is especially evident in the last stages of obesity and oncology.

What else can cause hypothyroidism? The reason may be hidden in the presence of parasitic and infectious diseases. A similar result can result in uncontrolled intake of hormonal drugs. Occasionally, cases of congenital hypothyroidism are identified. Veterinarians say that serious worm infestation can provoke hypothyroidism in dogs. The reasons are obvious - in the body of the animal is thrown out a huge amount of toxins that affect the thyroid gland.

Breeds with a predisposition to hypothyroidism

Hypothyroidism in dogs, symptoms (photos you can see in our article), clinical signs can be diagnosed in animals of different sex, age and breed. Although in the course of many years of observation it has been established that the symptoms of this disease are more often detected in animals under the age of ten. In 70% of cases they appear in dogs of large and very large breeds, and small animals suffer much less often.

Accumulated by experts from all over the world, statistics show that representatives of the following breeds are much more likely to fall ill:

• Doberman Pinscher;
• Golden retriever;
• Schnauzer;
• Irish Setter;
• Cocker Spaniel;
• Rate;
• Airedale terriers.

The German shepherd is predisposed to numerous genetic pathologies (including hypothyroidism). Under normal conditions, there is no gender dependence, however, bitches with ovaries removed suffer from this disease quite often. But such an operation is necessary to prevent breast cancer, so in this situation, hypothyroidism is the preferred choice: mortality from this disease is tens of times lower than cancer.

Symptomatics

Thyroid hormones are necessary for the normal metabolic function of the animal's body. The lack of them affects virtually all organs and systems. In this regard, hypothyroidism in dogs can be manifested in different ways. Symptoms and treatment of the disease are determined by the veterinarian based on clinical studies. However, there are several signs that can manifest themselves clearly in 90% of cases when the thyroid gland is broken.

The clinical picture of the disease can be considered only in a complex way, because separately some symptoms indicate the presence of another ailment. Dog owners should contact a veterinary clinic if the animal exhibits the following symptoms:

1. Differences in behavior (excessive aggressiveness or, conversely, shyness).
2. Violation of concentration of attention (apathy, floating sight).
3. Problems of a nervous nature (fatigue, overweight, intolerance to heat and cold, sudden mood swings).
4. Significant deterioration of skin and coat condition (dandruff, dryness, focal abaissement of hair, abnormal pigmentation, cornification of the skin).
5. Problems with reproduction of offspring (small or too large break between estrus, poor libido, weak or dead offspring, false pregnancy).
6. Violations in the work of the heart and blood vessels, as well as the hematopoietic system (bradycardia, arrhythmia, decreased platelet counts, as well as white blood cells, low hemoglobin, bleeding).
7. Changes in the work of the digestive tract (diarrhea, vomiting, constipation).
8. Problems with the eyes (conjunctivitis, dry eyes, fat in the cornea, eye infections).

Other serious signs are a stumbling gait, paralysis, sagging eyelids, problems with touch. Often the symptoms are manifested only at a late stage, as they develop gradually. Clinical signs, in general, may not appear for several weeks, or be so weak, "blurred" and periodic, that the owners do not immediately pay attention to them.

There is one more important aspect - this is the pathology of the thyroid gland. Often, after the dog has undergone intensive treatment with strong medications, the body may be weakened. Studying the medical card of the animal, the attending physician must take this fact into account, otherwise the diagnosis may be incorrect. Diseases of the kidneys, liver, diabetes and other diseases provoke a pathological syndrome of the thyroid gland.

Diagnosis of the disease

Hypothyroidism in dogs is diagnosed on the basis of the results of several analyzes. Their choice depends on the financial capabilities of the owners of the animal, the availability of modern equipment and the necessary reagents in the clinic. Since the signs of this disease are rather vague, it will not be possible to do without professional clinical diagnostics.

The most common analysis is a test for thyroxine (T4). This substance can be synthesized only by the thyroid gland. Therefore, with its low content in the bloodstream, one can assume the presence of this serious disease. However, it should be borne in mind that there are a number of other reasons provoking a decrease in thyroxine in the blood, so it is necessary to consider other diagnostic techniques.

Thyroxine may be present in the blood stream in two forms. The bound form joins the proteins and does not penetrate the cells. Free T4 is not bound to proteins, it is able to penetrate into cellular structures and, as a rule, is present in them in small amounts. Its volume fraction is taken into account in the diagnosis.

If the dog has a low level of T4, you can make an analysis for thyroxine, based on the effects of special medications. In this case, a small amount of pituitary synthetic hormone is administered intravenously. Six hours after the procedure, the dog is taking blood and checking the T4 level. If the animal is confirmed with hypothyroidism, the level of the hormone in its blood will be close to normal. In a healthy dog, the level of this substance will significantly exceed the upper limits of the norm.

Valuable information can be provided by routine research, which is carried out during a clinical examination. For this you need to do the following:

• Biochemical blood test with determination of the level of triglycerides and cholesterol and general clinical;
• Urinalysis (general);
• Echocardiography;
• electrocardiogram.

Hematologic examinations

Based on the data collected by veterinarians, approximately thirty percent of dogs develop hypoglycemia with non-regenerative anemia. In addition, data have been obtained that hypothyroidism in dogs often causes pathological hemostasis or provokes bleeding.

In the serum of a sick animal, the concentration of triglycerides and cholesterol is significantly increased. Hyperlipemia is a fairly common complication of hypothyroidism. Hypertriglyceridemia is much less common. Sometimes in the blood serum there is an increased content of liver enzymes and azotemia, from mild to moderately expressed.

Treatment

With each year of studying hypothyroidism in dogs, specialists are able to identify new data that affect the methods and ways of treating this ailment. Nowadays, a therapy scheme has been developed that includes an attempt to eliminate the cause of the disease and symptomatic treatment.

If the doctor was able to diagnose an inflammation of the thyroid gland at an early stage (Hashimoto's disease), it is very important to eliminate it to prevent hypothyroidism in dogs. Treatment consists in the administration of doses of synthetic thyroid hormone thyroxine ("Levothyroxine"). It should be entered daily. Complex therapy involves frequent blood tests to adjust the dosage of the drug.

Today, the world's pharmaceutical companies produce many varieties of this drug that differ only in registered names. The dose of the drug depends on the stage of the disease and the reaction of the animal to therapy. Initially, a standard dose is administered, after a day, a blood test is done, the hormone level is checked, after which the treatment is adjusted in accordance with the result obtained. The doctor determines which body system is particularly hard at responding to the disease and prescribes supportive and symptomatic treatment.

Patient monitoring and further prognosis

Two weeks after the start of treatment, the concentration of T4 in the blood plasma is checked. As a rule, the peak concentration is fixed in six to eight hours after taking the drug. During this period, the concentration of thyroxine should be as close to normal as possible.

Before the administration of the drug, the serum T4 content should be at the lower limit of the norm. A low concentration of T4 before and after taking the drug suggests an unreasonably low dose. This can be caused by a violation of absorption of the drug in the intestine, an incorrect schedule of administration or administration of the drug.

The need to adjust the dose of the drug is indicated by non-eliminated symptoms of thyroid insufficiency, or, conversely, symptoms of an overdose. The prognosis for adult animals with primary hypothyroidism who undergo appropriate substitution therapy is positive.

If the administration of thyroid hormones after long-term use is discontinued, it may take several weeks, and sometimes months, to restore the connection between thyroid hormones and the pituitary gland. Such recovery, as a rule, occurs without consequences for the health of the animal.