Hypothyroidism (SDU) – why does it often go undiagnosed for so long?

Hypothyroidism, medically known as hypothyroidism, is one of the most common hormonal disorders in dogs. It mainly affects middle-aged to older dogs, with Golden Retrievers, Dobermans, Boxers, and Beagles being particularly susceptible.

INHALT
Why is the thyroid gland so important? Causes and development Symptoms Diagnosis Treatment Forecast Prophylaxis
Why is the thyroid gland so important?

The thyroid gland is located in the neck area of dogs and influences almost all metabolic processes in the body through the hormones T4, T3, and calcitonin that it produces. The cells of the thyroid gland require amino acids and iodine to produce the thyroid hormones thyroxine (T4) and thyronine (T3). A sufficient supply of iodine is therefore essential for a functioning thyroid gland. Hormone production is controlled and regulated by the pituitary gland. Thyroid hormones are involved in the following tasks:

  • Development and maturation of the brain in the growing body
  • Regulation of hair growth
  • Thermoregulation
  • Increasing fat metabolism, accelerating food transport
  • Influencing heart rate and cardiac output
  • Increased immune system
  • Stimulation of red blood cell production
  • Influences calcium metabolism

Diagram of the thyroid gland in dogs
1 Larynx | 2 Thyroid gland | 3 Trachea
Causes and development

If the thyroid cells are destroyed, hormone production decreases and the thyroid gland can no longer function properly. Depending on the cause of this destruction, a distinction is made between primary and secondary hypothyroidism. Chronic inflammation of the thyroid gland or an autoimmune disease that leads to the breakdown of hormone-producing tissue is referred to as primary hypothyroidism. If hypothyroidism is only a consequence or side effect of an underlying disease, such as Cushing's syndrome, it is referred to as secondary hypothyroidism. Certain medications can also lead to an underactive thyroid gland.

Symptoms

The disease usually develops very gradually, so that many dog owners do not notice the onset. The first, very unspecific signs include tiredness, lethargy, listlessness, an increased need for sleep, and a tendency to gain weight. The coat may become dull and brittle, and skin changes and inflammation may occur. Increased susceptibility to infection, sensitivity to temperature, heart problems, hearing loss, ear infections, and eye problems may also occur. A "sad" facial expression is often observed, which is due to thickening of the skin in the facial area. If you notice such a slowly progressive change in your dog, have it examined by a veterinarian in good time.

Diagnosis

Based on your preliminary report and the clinical examination, the vet already suspects that your dog may have hypothyroidism. A blood test can provide further valuable information about the functioning of the thyroid gland and the general health of your dog. Changes in the blood count are not always immediately apparent at the onset of the disease, so further ultrasound examination may be necessary to confirm the diagnosis.

In some cases, despite appropriate symptoms, neither blood tests nor ultrasound examinations yield usable results. It is assumed that these dogs have subclinical hypothyroidism, which can only be confirmed by trial treatment with thyroid hormones.

Treatment

If hypothyroidism is diagnosed, the missing thyroid hormones must be replaced. This requires daily administration of tablets to your dog. The dose is adjusted individually for each dog, starting with an initial dose. Especially at the beginning of treatment, hormone levels should be monitored closely by your veterinarian to adjust the dose as accurately as possible. Administering the medication at the correct time also has a major impact on the success of the treatment and requires a lot of patience and consistency on your part as the dog owner. Your vet will draw up a detailed treatment plan for your individual case and can send the medication for your dog digitally to petsXL, so that you can find all upcoming medication doses in your timeline and set reminders for yourself.

The first signs of success are usually seen after about seven to ten days, when the dog becomes more alert and lively. A reduction in skin symptoms and significant weight loss are usually only noticeable after several weeks. Since the destroyed thyroid tissue does not recover, the treatment must be continued for life.

Forecast

It is not possible to cure a damaged thyroid gland. However, with well-adjusted and consistent treatment and regular veterinary check-ups, the symptoms mentioned above usually disappear completely and affected animals can once again lead a largely normal life.

Prophylaxis

The most important measure is an annual veterinary check-up with a clinical examination and monitoring of thyroid levels in the blood.