Content
- Hypothyroidism in dogs
- Primary hypothyroidism in dogs
- Secondary hypothyroidism in dogs
- Tertiary hypothyroidism in dogs
- Congenital hypothyroidism in dogs
- Canine Hypothyroidism Symptoms
- Diagnosis of Canine Hypothyroidism
- Hypothyroidism in a dog - treatment
Hypothyroidism in dogs is one of the most common endocrine disorders in dogs. Unfortunately, this is a difficult disease to prevent, as the causes are believed to be predominantly due to a genetic predisposition to hypothyroidism.
If your dog has recently been diagnosed with this disease or if you are simply curious to know more about it, PeritoAnimal has prepared this article with everything you need to know about it. hypothyroidism in dogs - causes, symptoms and treatment!
Hypothyroidism in dogs
The thyroid gland is largely responsible for regulating the dog's metabolism. Sometimes, due to an abnormality in this gland, not enough amounts of necessary hormones are produced in the dog causing what is called hypothyroidism. Hypothyroidism can arise from any dysfunction of the hypothalamic-pituitary-thyroid axis.
We can thus describe hypothyroidism as an endocrine disease characterized by a decreased production of thyroid hormones. The thyroid gland is responsible for producing the hormones T3, called triidothyronine and T4, called tetraiodothyronine. A low production of these hormones causes this problem so common in puppies.
Primary hypothyroidism in dogs
O primary hypothyroidism it is by far the most common in dogs. The origin is usually directly a problem in the thyroid gland, usually the undoing her. The two most common histopathological patterns are lymphocytic thyroiditis (a process in which the thyroid is infiltrated by lymphocytes, plasma cells and lymphocytes) and idiopathic thyroid atrophy (a process in which the gland loses its parenchyma which is replaced by adipose tissue) .
Secondary hypothyroidism in dogs
Secondary hypothyroidism is characterized by dysfunction of the pituitary cells themselves, causing decreased production of TSH hormone. This hormone is responsible for stimulating the thyroid to produce hormones and that is why it is called "secondary". There is a progressive atrophy of the gland, due to the absence of this hormone, decreased production of TSH and consequently of T3 and T4.
They exist different processes that can lead to this secondary hypothyroidism, namely[1]:
- pituitary tumors
- Congenital malformation of the pituitary gland (common in breeds such as the German Shepherd)
- TSH deficiency
- Surgical treatments or medications such as glucocorticoids
- Secondary to hyperadrenocorticism
Tertiary hypothyroidism in dogs
Tertiary hypothyroidism in dogs arises as a consequence of insufficient production of TRH, the hormone that releases thyroxine and stimulates the production of TSH in the anterior pituitary. That is, the problem is located in the hypothalamus, which produces the TRH.
This disease is extremely rare and there are practically no reports of this disease in dogs.
Congenital hypothyroidism in dogs
Congenital thyroid defects are very rare in dogs. However, they can sometimes occur and we could not fail to mention them. This type of disease is reported in puppies and puppies. used to be fatal.
One of the most documented causes of this type of hypothyroidism is the low intake of foods rich in iodine. Furthermore, it may be due to a defect in the iodine organification itself, the so-called dysormyogenesis or thyroid dysgenesis.
Canine Hypothyroidism Symptoms
The clinical signs of this disease appear around 4 to 10 years of age. Breeds with a greater predisposition to this disease are, among others, the Boxer, Poodle, Golden Retriever, Doberman Pinscher, Miniature Schnauzer and Irish Setter.According to some studies, there is no sexual predisposition to this problem, that is, it can affect males or females equally.[2].
the main clinical signs of this problem are:
- Weight gain and obesity
- Apathy
- Exercise intolerance
- Hairless areas (alopecia)
- Dry skin
- sebaceous skin
Anyway, the clinical signs of this disease are very varied and can range from dermatological, as described, to neuromuscular, reproductive and even behavioral. The thyroid gland intervenes in the entire metabolism of the dog, hence the great complexity of this problem.
Diagnosis of Canine Hypothyroidism
Although veterinary medicine is not as evolved as human medicine with regard to this disease, there are different alternatives to study the functioning of the thyroid gland and confirm whether the dog has a problem with hypothyroidism.
Your veterinarian will be based on clinical signs, thyroid function tests and the response to hormone replacement therapy to definitively diagnose the disease[2].
To correctly diagnose this problem it is necessary to take a measurement of the hormones in the dog's blood (mainly t4). Measuring blood levels of this hormone alone is not enough. However, if the values are normal or elevated, we can exclude hypothyroidism from our list of differential diagnoses. For this reason, this is one of the first tests to be performed when the veterinarian suspects this problem.
If we prove that t4 levels are low, it does not mean that we are necessarily present with a problem of hypothyroidism, it will be necessary to perform another test called the thyrotropin stimulation test (TSH) to confirm the definitive diagnosis.
In addition to these tests, it may be necessary to carry out other tests, according to the specific case of the animal. Namely:
- Nuclear scintigraphy (to determine the absorption of radioactive iodine)
- Antibody measurement
- Thyroid ultrasound.
- X-ray (if a thyroid tumor is suspected, to see if there are metastases)
Hypothyroidism in a dog - treatment
After the diagnosis is made, the veterinarian may prescribe hormone supplementation. Some veterinarians also use this method as a diagnosis, evaluating the response to treatment. The treatment of choice is based on levothyroxine sodium, synthetic T4.
In cases where dogs suffer from secondary or tertiary hypothyroidism it may be necessary to prescribe glucocorticoid and cobalt therapy.
Generally, after a week of treatment the animal begins to show improvement, increased appetite and general well-being.
It is very important to respect the dates of reassessment and visits to the veterinarian. Animals with this problem must be closely monitored as sometimes the veterinarian needs to readjust the treatment doses, according to the animal's response.
This article is for information purposes only, at PeritoAnimal.com.br we are not able to prescribe veterinary treatments or perform any type of diagnosis. We suggest that you take your pet to the veterinarian in case it has any type of condition or discomfort.