Cat Hyperthyroidism: Symptoms, Diagnosis, and Treatment
Hyperthyroidism is the most common hormonal disorder in older cats, and one of the most treatable.
Who Gets It?
Almost exclusively cats over 10 years. Affects approximately 10% of cats over 10.
Signs
- Weight loss despite increased appetite
- Increased thirst and urination
- Hyperactivity or restlessness
- Poor, unkempt coat
- Rapid or irregular heart rate
Treatment Options
- Medication (methimazole): daily tablet or gel. Effective and reversible.
- Radioactive iodine (I-131): curative in 95% of cases. Gold standard.
- Surgery: removal of the thyroid gland
Prognosis
Excellent with treatment. Most cats live for years after diagnosis.
Key takeaways
- Hyperthyroidism primarily affects cats over 10 years old, occurring in roughly 1 in 10 senior cats
- Classic signs include weight loss despite increased appetite, excessive thirst and urination, hyperactivity, and a matted coat
- Three main treatment options exist: daily medication, radioactive iodine (95% curative rate), or thyroid gland surgery
- With appropriate treatment, the prognosis is excellent and most cats enjoy years of good quality of life
Frequently asked questions
Can a cat recover from hyperthyroidism without treatment?
No, hyperthyroidism does not resolve on its own and requires veterinary treatment. However, the condition is highly treatable with medication, radioactive iodine, or surgery, all of which can effectively manage or cure the disorder.
Is medication safe for older cats with hyperthyroidism?
Yes, methimazole medication is a safe and effective treatment option for hyperthyroid cats. It works as a daily tablet or gel and is reversible, meaning you can adjust or stop treatment if needed.
What is radioactive iodine treatment for cat hyperthyroidism?
Radioactive iodine (I-131) is considered the gold standard treatment and cures hyperthyroidism in approximately 95% of cases. It targets and destroys the overactive thyroid tissue whilst avoiding damage to surrounding organs.
How long can a cat live with treated hyperthyroidism?
Most cats live for years after receiving appropriate treatment for hyperthyroidism. The prognosis is excellent with treatment, and cats typically maintain good quality of life.