There’s been a lot of coverage in the press lately about longer life expectancy in the cats and the subsequent rise in age related medical conditions.

Hyperthyroidism is a common endocrine condition most usually found in middle aged to older cats. It occurs when the thyroid gland produces an excessive amount of the thyroid hormones thyroxine (also known as T4) and triiodothyronine (also known as T3).

The thyroid gland consists of two lobes and is positioned in the neck. The thyroid hormones produced by the gland control the body’s metabolic rate. In hyperthyroid cats one or both thyroid lobes enlarge resulting in the excessive production of these hormones. The enlargement is most commonly due to benign (non-cancerous) change. A small percentage of cases (approx 2%) are caused by malignant (cancerous) change and this can result in more difficulty treating the condition.

The excessive production of thyroid hormones results in an increase in metabolic rate, which leads to the typical clinical signs of hyperthyroidism. These may include:

 • Weight loss despite a ravenous appetite

• Increased thirst and urination

• Change in temperament – increased aggression, restlessness

 • Rapid heart rate

 • Poor coat condition

 • Diarrhoea

• Vomiting

Treatment of hyperthyroidism is recommended in order to improve the affected cat’s quality of life and limit the deleterious effects the condition can have on various organs in the body.

There are 3 treatment options:

 1. Medical treatment – daily tablet administration to reduce the thyroid hormone levels.

2. Surgical treatment – an operation to remove the overactive thyroid tissue.

3. Radioactive iodine therapy – radioactive treatment to destroy overactive thyroid tissue carried out at a specialist centre.

Medical stabilisation is recommended initially, normally for a period of 3 weeks, in order to assess the cat’s response to therapy and enable a decision to be made for long-term management of the condition.

Vidalta is an oral medication containing the active ingredient carbimazole, which is licensed to treat feline hyperthyroidism. Once daily administration of Vidalta can control the disease by reducing the amount of thyroid hormones produced by the thyroid gland. The small tablets should be administered whole and ideally at the same time every day.

Cat’s receiving Vidalta should be monitored regularly with your veterinary surgeon in order to achieve the correct dose, check for side effects of the medication and monitor for additional complicating conditions. Blood samples will normally be carried out at regular intervals until the cat is stabilised, after which 3 monthly checks are suggested to monitor progress. Medical treatment does not cure the condition, so lifelong therapy is required.