Imagine if we could eat like a horse and lose weight.  This happens relatively commonly in up to 20% of cats older than10. It is caused by a condition called hyperthyroid disease. “She’s constantly hungry but losing weight” or “he’s as skinny as a rake and just getting old” are common refrains in the consult room which arouses my suspicions that there may be something I can fix.  I’m no miracle worker, but hyperthroid disease is a wonderful condition to diagnose because treatment saves lives and keeps cats healthy for longer, allowing them to enjoy their twilight years.  The disease was first reported in cats in 1979 and since then the incidence has increased sharply.  

Why?  It is the subject of much research but there are no clear answers – diet is thought to play a role in causing enlargement of the thyroid glands located alongside the wind-pipe in the neck.  These glands are usually not palpable unless enlarged so it is part of the routine health exam to check the size in all cats to detect changes.  The hyperactive glands produce elevated levels of the hormone thyroxine which causes alterations in heat control and metabolism.  I diagnosed a cat last week with the presenting complaint that he could not cope with the heat – it was a shocker few weeks in January but cats generally don’t pant like dogs!  He had also lost nearly 10% of his body weight (that’s only 450 grams but it is significant when you weigh 4.5kg) and had enlarged thyroid glands.  A simple blood test done in the clinic confirmed the diagnosis and showed that he also had elevated liver enzymes which is often the case.

Other common signs are vomiting, drinking and urinating lots, being hyperactive or lethargic, muscle wasting, weakness, diarrhoea, poor hair coat,  increased toenail growth,  and increased aggressiveness.  Owners can easily dismiss a lot of these symptoms due to the cat getting old or having a fur ball.  Left untreated they fade away, often develop heart problems and die prematurely.

Treatment involves daily medication for the rest of their lives or removing iodine from the diet totally by feeding a prescription diet.  The diet seems like the simplest solution but is only effective in indoor cats and some cats refuse to eat it.  Radioactive Iodine treatment is another option available in Melbourne at a few licensed vet clinics but the cat has to be boarded there for a week or so while they pass all the radioactive material out.  This provides a permanent cure in 90% of treated cats but is a large one-off expense and involves quite a bit of travel.  Surgical removal of the nodules is fairly simple but may not cure the problem, so most cats take the tablets hidden in some wet food and respond within a couple of weeks.  

It is a rewarding condition to treat as improvements are usually easily appreciated by everyone involved.  An annual health check of your cat done at the time of vaccination is often when these conditions are picked up.  Remember that aging isn’t a disease in itself and much can be done to help the older pet.

Fiona Cameron

Shepp Vets