In veterinary clinical practice, thyroid disease is one of the common endocrine problems, especially canine hypothyroidism and feline hyperthyroidism. These two diseases have an important impact on the health of pets, so we need to have an in-depth understanding of their basic knowledge, pathogenesis, clinical manifestations, diagnostic methods, treatment methods and follow-up testing. This article will provide clinical veterinarians with detailed guidance to better diagnose and treat these conditions.

Canine hypothyroidism is a common endocrine disease. The disease is mainly caused by insufficient secretion of thyroid hormones (T4 and T3). The disease may be caused by a variety of causes, including autoimmune disease, abnormal thyroid development, or exogenous factors. Among them, autoimmune diseases are the most common cause, in which the body's immune system abnormally attacks its own thyroid tissue, leading to hypothyroidism.

The clinical manifestations of canine hypothyroidism are diverse, including weight gain, hair abnormalities (such as sparse hair, thickened hair, hair loss), skin problems (such as dry skin, skin infections), fatigue, Decreased activity, lowered body temperature, slowed heart rate, etc. These symptoms may appear gradually and vary in severity depending on the severity of the condition.

If not diagnosed and treated, Hypothyroidism may cause the following harms:

1. Exacerbation of health problems: Untreated hypothyroidism in dogs can cause thyroid hormone levels to continue to decrease, which in turn worsens the dog's health problems. Symptoms may gradually worsen and include weight gain, coat problems, skin infections, fatigue, muscle weakness, etc., affecting the dog's quality of life.

2. Heart problems: Thyroid hormone has a great impact on the cardiovascular system. Untreated hypothyroidism in dogs may lead to heart problems such as slowed heart rate and irregular heartbeat, increase the burden on the heart, and even cause heart disease. serious complications such as degeneration.

3. Nervous system problems: Thyroid hormone also has an important impact on the nervous system. Untreated hypothyroidism in dogs may cause neurological problems, including changes in mental status, abnormal behavior, etc.

4. Metabolic problems: Thyroid hormone is an important hormone in regulating metabolism. Untreated hypothyroidism in dogs may cause a decrease in metabolic rate, affect energy metabolism, and thus affect the overall health of the dog.

5. Other complications: Long-term untreated canine hypothyroidism may also cause other complications, such as anemia, immune system problems, reproductive system problems, etc., posing a more serious threat to the dog's health.

Feline hyperthyroidism is a common endocrine disease, mainly caused by excessive secretion of thyroid hormones (T4 and T3) caused by thyroid adenoma or thyroid hyperplasia. This disease usually occurs in older cats, especially those over 10 years old.

The pathogenesis of hyperthyroidism mainly involves overactivity of thyroid tissue caused by thyroid adenoma or hyperplasia, resulting in excessive secretion of thyroid hormones. In cats, thyroid adenomas are the most common cause. These adenomas are usually benign, but can sometimes be malignant.

The clinical manifestations of feline hyperthyroidism usually involve multiple systems, including increased appetite but weight loss, increased activity, anxiety, increased heart rate, elevated body temperature, and digestive system problems such as vomiting and diarrhea. In addition, cats may also exhibit kidney-related symptoms such as polyphagia, polydipsia, and frequent urination.