An older, thinner cat despite a good appetite? – there may be a thyroid problem!

As part of the six monthly senior checks for cats, probably the most important monitoring is to do with a cat’s weight.  Subtle (and not so subtle) weight loss is often an early indicator of an overactive thyroid gland, especially where the appetite is good, or even increased.

For us humans it’s the opposite problem that we have, namely an under-active thyroid gland, with the knock on effect of a real problem shifting excess weight.

What are the signs of an overactive thyroid in cats?

As always, there’s no one obvious sign that will alert an owner or a Vet, but most commonly there’s a loss of weight despite a normal to increased appetite.  In some cats the appetite can be voracious and yet weight loss is just as pronounced.  In others the signs are a little more subtle.  An increased heart rate is often apparent, this being the result of the overactive thyroid gland driving the body’s metabolism faster and faster.   Think of it like pushing down on the accelerator pedal of your car.  Do that and the engine (the heart) is driven very fast and the fuel (food) is burnt up far too quickly – hence the increased appetite.  What we, as Vets, need to do is reduce the thyroid activity or else the heart will become damaged.  As the metabolism gets driven faster, the blood pressure starts to increase as well.  All in all, not a good situation to allow to get out of hand.  Hence the senior checks.

The diagnosis of an over-active thyroid is usually fairly straightforward.  A simple blood test can be checked against the normal level of thyroxine in the blood stream.  Too high and the diagnosis is made.  There is, as often is the case in medicine, a certain grey area but normally the numbers are pretty easy to interpret.  Along with a test of the thyroid activity Vets usually check on the condition of the kidneys as well, to ensure that any management of the thyroid is balanced by the needs of the kidneys.

So how do we mend an over-active thyroid?

Until recently this was very much a combination of pills and surgery or a very expensive course of radio-active treatment.  The good news for cats (and their owners) is that this has been made a whole lot easier by the introduction of a diet that “fixes things”.  If it sounds too good to be true then this is one of those rare occasions when it actually is that simple.  What the food does is to reduce the amount of iodine in the diet so that the sensitised over-active thyroid gland (which gets bigger due to excess iodine in the diet) naturally regresses to the normal size, or thereabouts, whilst still providing the body with enough iodine to function normally.  Of course a cat has to like eating the food, which can be a “challenge” in some cases.  So there will be a place for the previously used pills and surgery in those cats that are truculent about diet change, but for the most part it works very well.

As always, early diagnosis is important as the racing metabolism, due to an over-active thyroid gland, puts untold pressure on an older cat’s body.