Hyperthyroidism is not a very common disorder in dogs, but even so, it is worth knowing about this disease, as well as its causes, symptoms and possible treatment. In this article on our site we are going to start by explaining the main characteristics of the thyroid gland, since it is in it that the hormonal problem that is the basis of this disorder originates. We will describe the changes that we can notice in our dog, which are what will lead us to seek veterinary assistance. Once in the clinic, we will see the necessary tests for the diagnosis, in addition to the treatment of hyperthyroidism in dogs
What is hyperthyroidism in dogs?
The thyroid gland is located in the neck, in the trachea, behind the larynx or superimposed on it, with what is It can be felt on palpation if it increases in size, which is helped by its consistency. This size is highly variable and is related to iodine intake in the diet. The extension of feed consumption, made with very similar formulas, is standardizing the size of the thyroid in dogs and, therefore, hyperthyroidism is not usually a very common disorder.
The thyroid is accompanied by four parathyroid glands, next to it or included in it, that's why you have to be very careful in thyroid surgeries, so as not to remove too many. Thyroid hormones perform various important functions in the body related to metabolism and growth. Therefore, any modification in its operation will cause visible symptoms. Thus, the thyroid can produce less hormones than usual, which causes a condition called hypothyroidism, and also can happen contrary, that is, a high production and secretion of hormones, T4 and T3, which will cause the disease at hand: hyperthyroidism in dogs.
Symptoms of hyperthyroidism in dogs
Within the clinical picture that can be found in hyperthyroidism in dogs, the following signs stand out:
- Increased appetite (polyphagia) and water consumption (polydipsia), with the consequent increase in urination (polyuria).
- Wearing even though the dog eats more
- Heart rhythm problems, such as tachycardia.
- Nervousness.
- In some cases a larger or smaller lump in the neckmay be felt and/or observed. This increased volume of the thyroid can compress the trachea and cause symptoms such as cough or shortness of breath.
- Chronic diarrhea and vomiting.
- Sometimes, the tumor causing hyperthyroidism affects the vagosympathetic trunk and can cause Horner's syndrome (protrusion of the third eyelid, enophthalmia, etc.).
Hyperthyroidism in dogs usually affects medium or large breeds more, and tends to develop slowly, so at first you may not notice any symptoms.
Causes of hyperthyroidism in dogs
Hyperthyroidism in dogs is usually caused by a tumor growing on the thyroid gland. This tumor can be malignant and metastasize to other parts of the body. Fortunately, they are rare tumors. In addition, in most cases they do not modify hormonal values and, in others, they lower their production (hypothyroidism). Cases of hyperthyroidism are less frequent.
To reach the diagnosis, it is necessary to base it on the clinical symptoms, on the physical examination, which may include an X-ray and an ultrasound, techniques that will allow the tumor to be delimited and its presence or not to be verified. of metastases. Likewise, a blood sample is taken to determine the values of the hormone produced by the thyroid, T4. It is also possible to aspirate cells from the gland to examine their typology, although it is the biopsy that will give a more reliable result. An elevation of the hormone T4 will undoubtedly indicate a problem of hyperthyroidism. The problem is that thyroid tumors are usually detected late, which means that in a considerable percentage of cases metastases are already present at the time of diagnosis.
Treatment of hyperthyroidism in dogs
Once the diagnosis of hyperthyroidism in our dog is confirmed, the veterinarian will inform us about the appropriate treatment. As in the case of dogs, it is normal for this hyperactivity of the thyroid to be caused by a tumor, surgery is going to be the treatment of choice, although this The decision will depend on the type of tumor, its size, etc. Surgery is often chosen because of the malignant potential of these tumors, but it is possible to treat hyperthyroidism in dogs with medication or radiation therapy. Sometimes medication is given to shrink the tumor so that it is operable. In this surgery, as we mentioned, it is difficult to preserve the parathyroids (at least two of them must be preserved to avoid subsequent hypothyroidism). In addition, it is a highly irrigated area, so there may be considerable blood loss and the need for a transfusion. After the operation, it may be necessary to administer medication and, in any case, periodically monitor the status of T4. Sometimes, having to completely remove the gland, hypothyroidism secondary to the intervention may develop and, of course, will also require medication.
