Symptoms of hypothyroidism in dogs

Hypothyroidism in dogs is the most common endocrine disorder in dogs. This thyroid hormone deficiency causes many nonspecific symptoms, which can make the diagnosis complex.

Do you think your dog might be suffering from hypothyroidism? There is no need to worry: although this disease is unfortunately incurable, it is now very well managed in veterinary medicine and the health prognosis of a dog that is correctly treated is excellent. To help your dog live well with his disease, and to react correctly if you suspect hypothyroidism, here is everything you need to know about this hormonal disorder.

 

What is hypothyroidism in dogs?

Hypothyroidism is an endocrine disease, a disorder caused by a malfunction of the endocrine system, which is responsible for the release of hormones into the body. Hypothyroidism can also be referred to as a hormonal disorder or dysthyroidism, a term that suggests a dysfunction of the thyroid gland without specifying the type.

In this case, it is the thyroid gland that is affected. Dysfunction of this gland can lead to two pathologies: hyperthyroidism, when too many hormones are secreted, and hypothyroidism, when too few hormones are secreted. Hypothyroidism, which is of interest to us here, is the most common thyroid condition, and of all hormonal disorders, in the dog.

The thyroid gland is one of the most important endocrine glands in the body. It is located in the neck and has two lobes on either side of the trachea. It is directly controlled by the pituitary gland in the brain. The role of the thyroid is crucial: it regulates the metabolism of the dog, that is to say the rhythm of functioning of each of its organs.

Hypothyroidism will inevitably lead to a slowing of the metabolism, which is no longer properly stimulated, and consequently of all bodily functions. Normally, the thyroid secretes three hormones: T3 (Triiodothyronine), T4 (Thyroxine) and calcitonin.

The production of these hormones occurs when THS (Thyroid Stimulating Hormone), a hormone secreted by the pituitary gland, couples with iodine, a chemical element naturally present in the environment that the dog absorbs through its diet. Note that a large part of T3 is indirectly produced by the thyroid gland. In fact, this hormone is obtained by conversion of T4 by other organs, notably the liver and, to a lesser extent, the intestines.

At the same time, it is the T3 hormone that is most active in the regulation of metabolism and whose decrease is most noticeable.

 

Causes of hypothyroidism in dogs

Endocrine diseases are still somewhat shrouded in mystery, not because the cause cannot be determined, but because it is not always sought. Indeed, many dogs - and humans - can suffer from mild or even chronic dysthyroidism, which is often attributed to a poor lifestyle.

In fact, because the symptoms of hypothyroidism are not very specific (fatigue, digestive problems, lack of energy, etc.), it is easy to confuse this condition with the consequences of an unhealthy lifestyle, especially when the hormone deficiency is not very significant. Although hypothyroidism in dogs is a true physiological disorder, it should be noted that lifestyle does have an impact on the endocrine system and is suspected of promoting the development of hormonal disorders.

There are two types of hypothyroidism: primary and secondary. Tertiary hypothyroidism also exists in humans, but has never been described in dogs. Hypothyroidism is said to be primary when it is caused by damage to the thyroid gland itself, resulting in a total or partial inability to produce T4 and T3.

This is the most common hormonal disorder in dogs, accounting for approximately 95% of diagnosed cases of hypothyroidism. Primary hypothyroidism is due to destruction of thyroid cells which can be the result of two distinct mechanisms: lymphocytic thyroiditis and idiopathic thyroid atrophy.

Lymphocytic thyroiditis is an immune dysfunction in which the dog's own antibodies attack the thyroid cells. The involvement of antibodies in this condition suggests an autoimmune disease, although this is not yet certain.

It is also assumed that this immune dysfunction is genetic, as certain breeds seem to be predisposed to it, including the Schnauzer and the Hovawart in the first place, but also the Boxer, Dachshund, Doberman, Beagle, Golden Retriever, Great Dane and Poodle, to name only the most popular ones. Lymphocytic thyroiditis is a silent disease, which evolves without symptoms for years, and whose after-effects (destruction of the thyroid follicles) are irreversible.

Idiopathic thyroid atrophy, or idiopathic thyroid parenchyma atrophy, is a degeneration of the follicular cells, which are gradually replaced by fatty tissue. In contrast to lymphocytic thyroiditis, no antibodies are found in the analyses and the cause of this condition is still completely unknown today.

It is possible, but not proven, that this idiopathic condition is in fact the terminal phase of lymphocytic thyroiditis. This theory is partly based on the age of the canine patients affected by this pathology, which are more advanced than those in whom an autoimmune disease is detected.

Idiopathic thyroid atrophy and lymphocytic thyroiditis each account for 45% of diagnosed cases of primary hypothyroidism. Other phenomena can cause damage to the thyroid gland, but these are rare.

Cellular malformations, iatrogenic (drug-induced) damage, thyroid tumors, iodine deficiency or antithyroid toxins are all uncommon but possible causes. Secondary hypothyroidism is caused by damage to the pituitary gland in the brain, which secretes the hormone that controls the thyroid.

The origins of these disorders can be varied, and they not only slow down the endocrine activity, but also damage the thyroid cells.

 

 

 

Symptoms of hypothyroidism in dogs

Hypothyroidism usually progresses silently for years, and the first symptoms usually appear between the ages of 3 and 8, when the thyroid gland is already well damaged. The decrease in T4 secretion inevitably leads to a decrease in T3 production, which is supposed to stimulate, regulate and control the metabolism. As a result, the dog's entire metabolism slows down, and all organs are affected.

Unexplained and uncontrollable weight gain is typical of hypothyroidism. The dog is tired, sedentary, lacks energy and no longer burns the calories it consumes. The organism has difficulty regulating body temperature and the dog is more sensitive to cold, which can result in shivering, complaining and a desire to seek refuge in warm places.

The skin and hair are not spared. The hair cycle also slows down, and the hair that falls out is not replaced. A sparse coat, flakes and scales are typical of the disease. The skin cells are also affected, and one can observe an increased sensitivity to infections, mycosis, parasites, as well as redness, seborrhea and hyperpigmentation.

The dog's heart rate decreases, causing fatigue, shortness of breath and generalized weakness, which may result in visible failure of the hind legs. The dog's voice may also change, and its reproductive cycle stops. Females no longer go into heat and males no longer have a libido.

It should be noted, however, that not all dogs have the same symptoms, and that not all symptoms have the same intensity. Some animals do quite well and their hypothyroidism can be discovered incidentally during a routine examination. Others develop severe, sometimes life-threatening symptoms.

 

Treatment and prognosis of hypothyroidism in dogs

There is only one treatment for hypothyroidism and that is to replace the hormones that are no longer being produced by the thyroid gland with synthetic hormones. The treatment must be given for life, as hypothyroidism cannot be cured and the deterioration of the thyroid cells is irreversible.

The dose of synthetic hormones administered must be carefully calculated according to the dog's weight and adjusted regularly. When the treatment is well dosed, there are no side effects. As soon as the dog benefits from an adapted treatment, the disappearance of the clinical signs is done slowly, very gently. It takes a little patience to find a dog full of energy, but the prognosis is very good.

For all the owners who are worried about not being able to treat their dogs for financial reasons (life-long treatments are sometimes unaffordable), it is worth noting that medications to treat hypothyroidism are very accessible. A box of 200 tablets costs less than 15 euros, and generally allows to treat the dog for two or three months. It should be noted, however, that larger dogs will require larger doses and will therefore cost their owners a little more.

Treating your dog's hypothyroidism does not necessarily require a well-stocked wallet, but rather rigor, since you will have to administer medication to your dog without fail every day for the rest of his life.

 

 

What should I do if my dog has hypothyroidism?

If you suspect your dog has hypothyroidism, it is important to take him to a veterinarian who will do blood work and possibly an ultrasound of the thyroid gland to make a diagnosis. Properly treated, this disease has a good prognosis, but if left untreated, death is inevitable.

Also, it should be noted that hypothyroidism has a considerable impact on the metabolism and can cause serious and irreversible damage and even lead to the development of other pathologies (diabetes, renal failure, etc.). To avoid these complications, it is essential to treat this disorder as soon as possible, before the symptoms become severe.

Once diagnosed and treated, it is important to follow the veterinarian's instructions to the letter and to closely monitor your dog's health. With treatment, the dog should lose weight, which requires adjusting the dosage of his medication.

Any side effects should suggest an incorrect dosage, and if there is no improvement, a search should be made for other conditions, whether or not related to hypothyroidism.

 

FAQ

My dog has hypothyroidism, is it serious?
Hypothyroidism is a serious condition, as it can lead to death if left untreated. However, it is well treatable with medications that are often free of side effects and inexpensive. Furthermore, hypothyroidism is not a sudden disease. On the contrary, it progresses slowly and is not a life-threatening emergency. Therefore, dogs with this disorder are often diagnosed in time.

How much does it cost to treat a dog's hypothyroidism?
Hypothyroidism requires lifelong treatment, which can be frightening for many owners who fear they will not be able to afford it. Fortunately, the medications to be given daily to the animal are inexpensive. However, the veterinary examinations necessary to establish the diagnosis (blood tests, ultrasound, etc.) may require a certain investment, and the dog may need regular follow-up visits.

What are the symptoms of hypothyroidism in dogs?
In hypothyroidism, the dog's metabolism slows down. The disease is silent for years, then we observe an alteration of the general state of the dog, a damaged coat, a fragile and irritated skin, a weakness in the limbs, a great fatigue, breathing difficulties, a slow pulse... Obesity, the most obvious symptom, is typical of the disease and can take on impressive proportions.

Is there a cure for hypothyroidism in dogs?
No, there is no cure for hypothyroidism in dogs. On the other hand, a life-long treatment to make up for the animal's hormone deficiency offers an excellent prognosis. In addition, it is a simple and inexpensive treatment to administer (tablets).

How do I know if my dog has hypothyroidism?
Hypothyroidism is a silent disease that is difficult to diagnose until the first symptoms develop. After a few years, there is a general deterioration in the dog's condition (obesity, hair loss, skin rashes, shortness of breath, intense fatigue, etc.).

Veterinary examinations (blood tests and ultrasound) are essential to confirm the diagnosis. Hypothyroidism is the most common hormonal disease in dogs. Particularly difficult to detect, it causes non-specific symptoms that are often associated with an unhealthy lifestyle (obesity, sedentary lifestyle, stress, etc.).

It is in fact a physiological disease that must be medically treated, otherwise it will be fatal for the dog. Fortunately, the treatment required to counteract the hormone deficiency caused by hypothyroidism is inexpensive and relatively simple: it consists of tablets to be given daily to the dog for life.

With proper management, the dog will be able to live a normal life again, and its longevity will not be affected.