Hypothyroidism in dogs is a disease caused by the improper functioning of the thyroid gland and the consequent decrease in the production of thyroid hormones. Hypothyroidism causes very varied and very non-specific symptoms. The positive thing is that it can be easily treated, although it is a chronic disease.
In this article on our site we are going to explain the symptoms, causes and types of canine hypothyroidism, as well as its diagnosis and treatment. If you suspect that your four-legged friend may be suffering from this disease, read on to find out all about hypothyroidism in dogs
What is canine hypothyroidism?
Hypothyroidism in dogs is a disease that causes a deficit in thyroid hormones that is responsible for producing thethyroid gland , located in the throat, below the larynx. The hormone called T4 or thyroxine is what controls the body's metabolic rate. Therefore, a decrease in the amount of this hormone in the blood will have consequences on the dog's metabolism, which is reduced, which translates into a large number of non-specific symptoms.
Causes of hypothyroidism in dogs
Any problem that affects the functioning of the thyroid gland can cause this disease. Thus, canine hypothyroidism can occur when the dog's own immune system attacks the thyroid gland and damages or destroys it. It can also be due to a degenerative problem in which the gland tissue is gradually replaced by fatty connective tissue. An abnormal growth of cells in the thyroid gland is another less common cause. In a smaller number of cases, hypothyroidism is not caused by a problem in the thyroid, but in the pituitary gland, which regulates the production of T4.
Although dogs of any age can suffer from hypothyroidism, the disease is more common in middle-aged dogs of medium and large breeds. Any dog can get the disease, but it is more common in:
- golden retriever
- doberman
- labrador retriever
- boxer
- dachshund
- Cocker spaniel
- beagle
- airedale terrier
- Great Dane
- Irish setter
- miniature schnauzer
Types of hypothyroidism in dogs
Canine hypothyroidism can be primary or secondary. Primary is by far the most common. We explain it in more detail:
- Primary hypothyroidism: basically due to lymphocytic thyroiditis, autoimmune or Hashimoto's, which is hereditary, or an idiopathic atrophy of the thyroid gland. In both disorders, thyroid tissue is destroyed. In a smaller number of cases, the cause is a neoplasm in the thyroid gland.
- Secondary hypothyroidism: can be caused by trauma, tumors or malformations in the pituitary gland, iodine deficiency or excessive use of glucocorticoids.
We can also talk about congenital hypothyroidism, diagnosed in young dogs. The most typical symptom is dwarfism, in addition to dermatological problems, constipation or changes in mobility.
Symptoms of hypothyroidism in dogs
The signs of hypothyroidism in dogs are varied and non-specific, as the disease affects the entire body. Therefore, the consequences of hypothyroidism in dogs can be many and it is important to go to the vet as soon as possible. We can classify the symptoms according to the affected area, these being the most common:
General symptoms
As general and most common symptoms, we find:
- Lethargy.
- Cold intolerance.
- Exercise intolerance.
- Weight gain.
- High cholesterol.
- Constipation.
- Anemia.
- Immunodepression.
- General weakness.
Neurological symptoms
The neurological symptoms of hypothyroidism in dogs tend to be more common in cases of secondary hypothyroidism. The signs that can alert us are:
- Facial paralysis.
- Head tilt.
- Balance disorders.
- Ataxia.
- Weakness in the legs on one side.
- Limp.
- Seizures.
Dermatological symptoms
Within the extensive list of symptoms of hypothyroidism in dogs we also find skin signs. In these cases, it is common to observe symmetrical bilateral hair loss from the front of the neck to the chest, sides, backs of the thighs and the top of the tail. In addition, the dog with hypothyroidism may develop the following dermatological symptoms:
- Dry, thickened, inflamed and darkened skin.
- Matt, dry and brittle hair.
- Seborrhea.
- Little hair growth, which also falls out easily.
- Pustules and irritations.
- Fluid buildup on the face.
Cardiovascular symptoms
Within cardiovascular signs we highlight:
- Slow heart rate.
- Abnormal heart rhythm.
- Atherosclerosis.
ReproductiveSymptoms
A deficiency of the hormone T4 in dogs can also cause consequences in the reproductive system, such as these:
- Infertility.
- Absence of heat.
- Milk secretion outside lactation.
- Enlarged mammary glands in males.
Eye symptoms
Eye he alth can also be affected when the functioning of the thyroid gland is altered, causing the following problems:
- Blepharitis.
- Corneal ulcers.
- Abnormal eye movements.
- Corneal dystrophy.
Behavioral Symptoms
Finally, and as happens in other pathologies, the dog with hypothyroidism can present certain signs that could be confused with behavior problems such as these:
- Aggressiveness, which can be context-independent, unpredictable, and intermittent.
- Fear.
- Exaggerated shyness.
- Compulsive behaviors.
- Signs similar to cognitive dysfunction syndrome.
- Hyperactivity.
- Learning problems.
It should be noted that the presence of behavioral changes associated with canine hypothyroidism is still controversial. Aggressiveness is the most cited, but it is not known if is a symptom or hypothyroidism has aggravated an existing problemFinally, other symptoms of hypothyroidism are deafness or megaesophagus. In addition, it is associated with other diseases such as dilated cardiomyopathy, von Willebrand disease or myasthenia gravis.
Diagnosis of hypothyroidism in dogs
If your dog has some of these symptoms and you wonder how to detect hypothyroidism in dogs, the truth is that there are several tests, which, of course, have to be requested and interpreted by the veterinarian. Typically, this professional draws a blood sample and asks for the concentration of free T4 in the blood. If this thyroid hormone test shows normal values, the possibility of hypothyroidism is ruled out. But a low concentration does not imply hypothyroidism, so more tests are done, such as the TSH-induced stimulation or the test of thyroglobulin autoantibodiesAn ultrasound of the thyroid gland may also be done.
Treatment for hypothyroidism in dogs
The treatment for this disease is quite simple, but, in general, it must be given throughout life and it is necessary that the veterinarian prescribes a follow-up and control to establish the appropriate dose. At first this will be calculated based on the weight of the dog. The treatment consists of pills for hypothyroidism in dogs. Let's see it in more detail:
Drugs for hypothyroidism in dogs
As this disease is caused by a lack of hormones from the thyroid gland, the treatment is based on supplying the body with the hormones it lacks. In this way the symptoms subside, although it will take several weeks or months to do so. Specifically, the dog is given once or twice a day levothyroxine sodium, which is a synthetic form of the hormone T4 Because levothyroxine comes in tablets, it is very easy to take with food. Remember the importance of adjusting the daily dose, only then will it be effective. Of course, only the vet can do it.
Diet for dogs with hypothyroidism
Dogs with hypothyroidism should receive a quality diet adjusted to their vital circumstances and based on animal protein. In hypothyroidism in dogs, contrary to what happens in other pathologies, diet is not the basis of treatment, but it can help alleviate some of the symptomsthat occur in sick dogs.
Thus, for example, a restricted diet in fats and carbohydrates can help those dogs that have increased their weight to regain optimal weight, a correct intake of fiber prevents constipation or iron improves dogs with anemia. As there are so many symptoms that can also appear simultaneously, the ideal is that we follow the advice of the veterinarian to choose the food that can most increase the well-being of our dog.
