Hyperthyroidism is the most common endocrinopathy (hormonal disease) of cats. It mainly happens in older kitties (usually greater than 10 years of age).
Hyperthyroidism means excessive thyroid activity. It causes a sustained high metabolic state produced by thyroid nodules secreting too much thyroid hormone. 98% of these nodules are benign, but this very high metabolic rate causes symptoms.
- The most typical scenario is a cat that is losing weight despite good appetite.
- Another common finding on physical exam is a very rapid heart rate with the presence of a heart murmur.
- Other signs may include intermittent vomiting, increased drinking, diarrhea, behaviour change and poor hair coat.
Diagnosis is made via a blood test which shows elevated thyroid level.
The 3 most common ways that we can treat hyperthyroidism include:
- Methimazole – a medication which blocks the pathway that leads to the formation of thyroid hormone. This medication comes in the form of a tablet or a transdermal gel that is applied to the inner part of the ear.
- Y/D Diet – is a special diet from Hill’s. It is an iodine-deficient diet that is effective in lowering thyroid hormone levels. This diet is only suitable for indoor cats, and the diet must be very strictly adhered to.
- Radioactive Iodine Injection – this is a potential cure for hyperthyroid cats but does require a 1 week stay at a referral clinic in Victoria or in the Lower Mainland. The radioactive iodine is absorbed into and destroys the problematic thyroid tissue. It is curative in 98 – 99% of cats.