My 15 year old feels bony along her back but the vet said she was fine in spring. How much weight loss is too much in an old cat?

First post, long time reader. Mabel is 15, tortie, still eating well, still bossing the dog about. But when I stroke her now I can feel every bump of her spine, and her hips feel like a coat hanger under the fur. She had her check in April and the vet said she was in good shape for her age.

I don't have a number to compare because I've never weighed her at home. I keep telling myself old cats just get bony, my mum's cat did. But she also seems to be at the bowl a LOT more than she used to, which I'd assumed was a good sign?

Is there a point where thin becomes worth a phone call, or am I fussing over an elderly lady who is just elderly.

Ruth K. said:

she also seems to be at the bowl a LOT more than she used to

That bit, plus bony, is the combination I would not sit on. Smudge's brother did exactly that at 15 and I thought the same, eating loads means he's fine. Turned out it was the opposite. Thyroid.

Not saying that's what it is. Just that eating more and getting thinner isn't the reassuring pair it sounds like.

Get a number before anything else. Bathroom scales: you on your own, then you holding her, take one off the other. Write it down with the date. Then ring the practice and ask what she weighed in April, they will have it on her record.

With Willow the difference between the April weight and the September weight was the whole conversation. Without it I was just a woman saying she looks a bit thin, which every vet hears ten times a day.

Did the scales thing (the dog tried to get on too). 3.4kg. Rang the vet, April was 3.9. I did not expect that. Half a kilo off a cat that small seems like a lot when you write it down.

Ruth K. said:

April was 3.9

Ruth, that's a genuinely useful number, and yes, it's enough to book her in rather than wait for her next routine visit.

To put it in proportion: 500g from 3.9kg is a loss of roughly 13 percent in about five months. There's no magic cut-off, but a steady, unexplained loss on that scale in an older cat is worth a vet check on its own, even when the cat seems bright and well. Some very elderly cats do thin out gradually, but weight loss is also the first visible sign of most of the common senior illnesses, so it needs ruling out before it gets filed under age.

The appetite is the other important part of the picture, because it changes the shortlist. Weight loss with a normal or bigger appetite most often points towards an overactive thyroid, and less often diabetes or a gut problem that stops food being absorbed. Weight loss with a fading appetite points more towards kidney disease, dental pain, or other illness. More thirst, vomiting, a scruffier coat, or restlessness at night are all worth mentioning, so jot down anything you've noticed.

What the visit will usually involve is an exam, including a feel of the neck for the thyroid gland, bloods covering kidney values, glucose and a thyroid level, a urine sample if they can get one, and a blood pressure reading. What any of it means for Mabel is for whoever examines her. The site's guide to senior cat vet checkups goes through what gets checked and what the tests look for, if you'd like to read up before you go.

And for everyone reading: a cat that was in good shape at a spring check can still have changed by autumn. That's exactly why senior cats are seen more often.

Update. Bloods came back with a raised thyroid level, kidneys OK for her age thankfully, blood pressure slightly up which the vet said often goes with it. She's started on tablets and we go back in three weeks for a recheck and a weigh. 3.45kg at the vet, so at least she hasn't dropped further.

I'd never have rung without the number. Weighing her on the first of every month from now on, and the dog can wait his turn.