Learn Hypothyroidism in Dogs: Symptoms, Treatment, Diet

Hypothyroidism in dogs is one of the diseases we have in common with our pets.

Thyroid hormones play a fundamental role in the functioning and maintenance of multiple body organs in humans and dogs. 

A deficit of these results in a lethargy of metabolic activities that determine the minimum energy needs required for the organism’s optimal functioning. This condition is known as hypothyroidism.

What is Hypothyroidism in Dogs?

The thyroid gland secretes a large amount of a variety of hormones necessary for the regulation of the functions of individual organs and the body as a whole, allowing a correct balance to occur between the organs. The thyroid is located in the middle area of ​​the neck near the larynx.

By not producing sufficient amounts of any or all of the hormones, you get to suffer from this condition.

It is a hormonal imbalance derived from the volume variation (whether it is reduced or expanded) of the thyroid, which generates a progressive weakening that gradually destroys the cells that make it up.

This condition usually occurs in dogs from middle age to those who are well into old age. However, there is more tendency to appear in breeds of medium to large size.

The main hormones secreted by the thyroid are thyroxine T4 and triiodothyronine or T3, whose deficiency manifests itself in a considerable and appreciable decline in metabolic activity.

When this happens, many symptoms appear that cause the dog’s health to be seriously compromised by generating a series of complications.

Causes of  Hypothyroidism in Dogs

This disease has various causes, but one of them is when there is a disproportionately abnormal growth of gland cells. This growth causes it not to function correctly while the tissue degenerates to be replaced by adipose (fatty) tissue.

Another possible cause is the immune system, which attacks the gland, damaging or destroying it. There are cases in which it is derived from an incorrect functioning of the pituitary gland.

This is the main gland of the endocrine system, located at the base of the skull, and its function is the regulation of the thyroxine or T4 hormone.

Dog Breeds More Prone to Hypothyroidism 

As mentioned above, all dogs can have hypothyroidism, but the breeds that tend to develop it are medium to large dogs.

Hypothyroidism in Dogs: Symptoms

Several factors may indicate that the dog suffers from this condition since they are a symptom of a lack of adequate hormonal production.

Symptoms include the following:

Weight Gain

By reducing their metabolic rate, dogs tend to increase their weight considerably. They can develop weight of around 50% greater than healthy animals.

By gaining so much mass, the dog tends to become more sedentary since movement and physical activity are more difficult. Therefore, it is a dog that consumes less energy.

However, it must be taken into account that obesity is not a direct consequence, nor is the latter its primary cause. Obesity is also related to the food quality and the amount supplied by the dog.

Similarly, sterilization and other diseases can be the source of weight gain.

Hair Loss

Alopecia consists of spontaneous hair loss without showing any related symptoms, such as itching, which usually accompanies and is the cause of its fall. In that case, it is something more spontaneous without immediate consequences.

In dogs, alopecia can present in its variant of endocrine alopecia and is observed with the loss of fur in specific areas such as the neck, elbows (especially in larger breeds), tail, or in nasal area.

This specific type of alopecia indicates that the dog could be suffering from this ailment, a symptom in more than 80% of cases. When this symptom appears, it takes a long time to recover its fur naturally, or it may not even recover.

Also, the remaining fur could show a rough, fine appearance without its natural shine.

Eye Signs

Although ocular symptoms are not usually common in cases derived from hypothyroidism, cases may occur. This is because the high levels of cholesterol in the blood and the fat that circulates in it cause specific changes in the eyeballs, such as corneal dystrophy, which consists of a variation of the eye’s cornea.

Generally, this is the appearance of a white dot on the eye’s surface, but it does not represent a danger to the dog’s visual health at this stage.

However, when it gets worse, bubbles usually appear, which is very uncomfortable and annoying for the dog and ends up in ulcerations. If so, they require proper treatment by an expert veterinarian.


As the deficiency of the hormones produced can considerably affect many organs and tissues in the animal’s body, it is not surprising that the symptoms are reflected in various and multiple areas.

However, as the deterioration of the thyroid gland usually occurs progressively, the symptoms will not all appear at the same time, but rather as the thyroid deficiency evolves, which can cause them to be overlooked until it is already evolved the illness.

Among the main symptoms that are shown and of which constant observation must be maintained are the following:

  • Skin infections result in a scaly texture with a bad smell due to the appearance of a layer of fat on it.
  • Along with the appearance of the alopecia above, a deterioration in the hair’s health can also manifest itself, turning dark and dry, making it brittle and very fragile.
  • The skin becomes thicker and darkens, especially in areas with more friction, such as the groin or armpits. Skin folds may form due to the same thickening.
  • Infections can appear and develop in the ears and ears, which can cause bad odors and redness.
  • The dog tires quickly, increasing sleep cycles and reducing physical activity.
  • The cold climates will become intolerable, forcing them to find where to take shelter and warm up.
  • Presence of anemia.
  • Increased cholesterol levels.
  • Lethargy in periods of vigilance.
  • Irregularities with the reproductive and central nervous systems. Although these symptoms do not occur as frequently, they can be derived from this disease.

How is hypothyroidism in dogs Diagnosed? 

One of the best ways to diagnose hypothyroidism in dogs is to have your vet perform a blood test. In this test, the levels of T4 and FT4 must be measured, which are the hormones responsible for regulating the levels of fat, protein, and carbohydrates in the body.

If the values ​​are low in the results, it will be a clear indication of this condition’s presence. The diagnosis can be verified through a TSH stimulation test and/or an ultrasound.

If the diagnosis is confirmed, the vet will begin treatment so the dog can have a healthy life even though this disease has no cure. This usually consists of giving the dog some tablets that contain L-Thyroxine, which helps the system maintain its regular levels of thyroid hormones.

The veterinarian determines the appropriate dose based on various factors and observations of the symptoms and behavioral changes in the dog. The adopter needs to be vigilant in case they notice their dog losing weight rapidly or starting to drink too much water.

If so, you should return to the office as soon as possible so that the treatment dose can be adjusted again. If your dog is taking medications to treat other conditions, it may have low levels of thyroid hormones as side effects of those medications without necessarily causing thyroid gland problems.

Some medications include anticonvulsants such as Phenobarbital, prednisone, or another steroid. Also, with certain non-steroidal anti-inflammatory drugs, Propranolol (a heart medicine), Clomipramine (which controls your behavior), and some sulfa-class antibiotics.

It is essential to mention that some breeds of dogs, such as greyhounds, sighthounds, whippets, and Irish Wolfhounds, by nature, tend to have lower thyroid hormone levels than other breeds.

The vet is trained and has the necessary experience to determine precisely if it is hypothyroidism or a consequence of consuming these medicines.

The expert must analyze the complete set of factors; therefore, it is essential to visit the doctor who treats your dog regularly. It is necessary that the veterinarian first know the medical history of the dog and if it has suffered or suffers from other diseases.

Equivalently, he will make observations regarding how long he presents symptoms and external factors such as lifestyle and diet.

Hypothyroidism in Dogs Treatment

Hypothyroidism in Dogs

As mentioned, this disease has no cure but can be treated through thyroid hormone replacement therapy. This therapy is for life. The FDA approves two drugs for this purpose: THYRO-TABS CANINE and ThyroKare.

These medicines have levothyroxine sodium as the active ingredient.
Of course, the only one in charge of determining the dose the dog should take is the veterinarian, who must consider your pet’s weight, among other essential factors.

With these medications, the improvement in dogs will be evident after several weeks of continuous use. Following the expert’s indications, the dog will have an improvement in activity level, which will be very positive.

If the dog has hair loss, it could take longer to grow, around four months.
If you have problems with your ears and skin, it could also take time and require additional medications to be given.

Hypothyroidism in Dogs Diet

Food plays a really important role in a dog’s health and even more so in hypothyroidism in dogs. In this sense, although the medicine indicated by the doctor is vital, it must always be accompanied by a correct and adequate diet.

Therefore, it is an essential part of the treatment to be successful. In this sense, it is recommended that adopters take the following into account when feeding their dog:

  • Proteins: The dog consumes food with proteins of animal origin and good quality.
  • Low Carbohydrates and Fats: You need to limit the number of carbohydrates you eat, just like fats. This way, you can return to your ideal weight if you are overweight or obese.
  • Fiber:  High fiber intake is essential. Also, it is excellent for constipation.
  • No artificial additives. It is necessary to avoid foods with artificial colors or aromas because these can affect thyroid function.
  • Iron: They require an adequate supply of iron to prevent the presence of anemia, which is another symptom.
  • Without cereals: The cereals used to prepare feed for dogs can often affect the hormonal balance.

This type of diet meets the above requirements and has a team of veterinary nutritionists at your disposal. If you have any questions, you can contact them so they can make any necessary dietary adjustments.

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