cats, hyperthyroidism in cats, indoor cats, keeping pets safe, thyroid disease

Your Cat’s Thyroid

My dear departed cat Salem, along with his failing kidneys in his later years, also developed hyperthyroidism when he was about 7 years old.  This is another common ailment of our furry friends when they get to middle age.

Before this illness developed he was a very overweight cat weighing more than 12 kilograms and I had him on weight loss food.  He was an indoor/outdoor cat and we lived in Canberra, Australia’s bush capital.

I knew that something was wrong when he all of a sudden lost almost half his body weight.  I took him to the vet and they diagnosed hyperthyroidism.

What is hyperthyroidism?

The thyroid gland in cats, like humans, is a butterfly-shaped organ residing in the neck that produces the thyroid hormone.  This in turn regulates metabolism.  When a cat becomes hyperthyroid – the gland is working too hard and starts to produce excessive amounts of the thyroid hormone (T4) in the bloodstream which creates a whole bunch of health issues in both cats (and humans).  In most cats a small benign tumour will form on one or both sides of the thyroid gland sending the gland into panic mode where it starts to over-produce T4.


The most common signs are dramatic weight loss accompanied by an increased appetite as well excessive thirst, increased urination, hyperactivity, vocalisation (sad meowing) over-grooming and unkempt appearance, panting, diarrhoea and sometimes shedding and vomiting.

Immediate Treatment

Initially my vet put my cat Salem on a dose of Methimazole for a year or so. Over time, this would have been an expensive solution as my cat was then only 7 and he would have required that medication for the remainder of his life.  We were also advised that this medication had the potential for side effects including loss of appetite, lethargy and possible blood cell abnormalities.  Although while he was on this medication, we did not notice any adverse effects with our cat Salem.

The medication will suppress production of the thyroid hormone but it will not slow the growth of the tumour and over time the dosage will likely need to be increased to manage the condition.

white oval medication pill beside blister pack
Photo by Pixabay on

More permanent treatment options

Because of his age and general health we decided to proceed with the more costly, but supposedly permanent solution, which was radioactive iodine therapy. Radioactive iodine becomes concentrated in the thyroid gland, where it irradiates and destroys the overactive thyroid tissue and no anaesthetic is required. This seemed like a good choice despite the AUD$1500 price tag initially as it still was cheaper than giving him the medication every day for the rest of his life.

In Australia at the time (2010) the treatment was via special radioactive capsules.  Salem was then put in isolation in a special licensed animal hospital for a week or so until we were able to collect him.  With this treatment you cannot take your pet home until the radioactivity from the isotope they are administered has destroyed the failing organ and the radiation has decayed to safe levels. They check this by testing the animal’s faeces and urine.

I believe now that there is a treatment where the cat is anaesthetised and given an injection of radioactive iodine and that this treatment is becoming more affordable for the average pet owner.

This treatment worked, or so we thought, for several years.  Then, the thyroid problems resurfaced and we had to give him capsules for the remainder of his life.  The vet advised me that the radioactive iodine treatment was 99% effective.  Unfortunately we were the 1 percent and my cat’s tumour grew back and we had to continue with the medication treatment option as we couldn’t justify another $1500 for a repeat of the radioactive iodine therapy.

Left untreated, your hyperthyroid cat will likely die of heart failure as the over production of the thyroid hormone continues to put stress on their hearts and all their other organs.  Untreated cats will sometimes have blood in their stools and some will stop eating altogether.

My cat Salem lived to the ripe old age of 17 years.  He eventually passed after developing kidney disease which became untreatable (see my other blog post).

Strangely, I too have thyroid disease (Hashimoto’s) and I take thyroid hormone tablets because my thyroid no longer produces the hormone (hypothyroid) the opposite problem.  I was such a kindred spirit to that cat and I believed I developed my auto-immune thyroid disease in sympathy with him.

adorable animal blur cat
Photo by Kelvin Valerio on
black cats, cats, indoor cats, keeping pets safe, kidney disease, sadness

Kidney Disease and Your Cat – the Silent Killer

Four years ago I had to have my beautiful black cat Salem euthanised after he had lost stacks of weight and was hardly able to get around.  He was 16 years old and such a beautiful cat.  At one stage he had weighed 12 kilograms when he became quite overweight as desexed male cats tend to obesity as they age.  He was an indoors and outdoors cat.

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My Cat Salem a few weeks before he died

Here my Salem is shown above a few weeks before he became really ill with kidney disease.  I took him to the vet on his last day as he had lost so much weight and had a very sad little meow and could hardly walk.  I asked my vet for her advice and said I was hesitant to euthanise if there something else that we could do.  She conducted the blood tests and advised me that his kidney function was virtually zero and that he would die a very painful death within 24 hours.  So I had to make that difficult decision to have him put to sleep.

Salem’s final moments

As the needle was entering his poor depleted little body,  he gently turned his face towards me and it was as though the expression in his eyes was saying “thank you”.  This was one of the saddest moments of my life.  My then 8 year old son, shown in the picture above was with me.  He had grown up with that cat.  I still miss my Salem three years on from then.

I am writing this article because I want people to know what preventative measures they can take about the silent killer of kidney disease.  I knew my cat Salem had kidney disease for some years.  He had also been required to have radioactive iodine on two separate occasions for thyroid disease as well, which was quite unusual as that treatment usually does the trick.  I will write a separate article about thyroid disease in cats and how that is addressed.  Because I knew that Salem had kidney issues, which is in any event, quite common in cats of advancing age, I had been feeding him Hills Science Diet or Royal Canin dry food specifically designed to address dysfunctional kidneys.  Those science diets do make quite a bit of difference to extending the lifespan of a cat prone to or with early stages of kidney disease.

Silent killer

The worst thing about kidney disease in cats is that you most often don’t realise they have it until it is too late.  What we do know is that, it is extremely common and that 1 in three cats will be affected by it.

Kidney disease is a leading cause of suffering and death in cats and because of its stealthy nature it is difficult to identify until after permanent damage is done.

You can keep an eye out for kidney stones, urinary tract (bladder) infections or hereditary conditions which might make the disease more likely to occur.  You should always be encouraging your cat to drink more water.

More than 50 percent of cats over the age of 15 years have kidney disease.


Early Symptoms

Most cats show no outward signs until the disease has progressed.

The first signs of kidney disease include:

  • subtle but continuous weight loss.
  • constant urinating.
  • thirsty and drinking lots of water.

My wonderful cat Salem, many years prior to his passing, developed a really bad bladder blockage requiring us to have him catheterised under Morphine.  This procedure fixed the problem and it was then I put him on a kidney-friendly diet.  This was 10 years before he died.  So he was a seemingly healthy 6 year old cat with early onset kidney problems.  The kidney-friendly cat food no doubt helped prevent the build of calcium crystals in his urine and, I think, kept him going for that extra decade.

More serious symptoms

  • A dramatically increased output of urine.  With some indoor cats you will see them flooding the litter box.
  • Increased thirst.
  • Weight loss.
  • Incontinence and peeing in unusual places.
  • Bad breath with a peculiar chemical smell.
  • Lethargy.

In the case of my Salem I saw dramatic weight loss – from 12 kilograms to about 6 kilograms within a few weeks and he became extremely lethargic.  I took him straight to the vet but by then he was in chronic kidney failure.

russian blue kitten on brown woven basket
Photo by Vadim B on

As a pet owner, the best thing you can do is be vigilant.  Watch your cat’s behaviour, diet, toilet habits, and even their grooming, and if any of the early onset symptoms present take your cat straight to the vet.  There are new early screening tests which you can have done these days and many cats with early stages of kidney disease can live long happy lives if their diet is managed and they have a constant supply of fresh water and love.

I know I did the best I could with my wonderful cat Salem.  I gave him a great life.  I still miss that cat.  He followed me everywhere, even to the toilet. My Cat Salem helped me weather many storms in my life and was around for the birth of both my children and he used to sit by and watch my kids when they were just tiny humans.  I dedicated my pet furniture company to him and I named my Twitter feed (MyCatSalem) after him.

Vale Salem…