Signs of kidney disease in cats, and why she hid them

What are the signs of kidney failure in cats?

If you're here, you've probably got a cat who's drinking more than she used to, or a diagnosis in your hand and a nagging question about what you should have seen. I'll answer the first one properly below, and the second one now, briefly: she hid this, the way cats hide nearly everything, and she was good at it.

The signs come in roughly three layers. There are early ones that creep in so slowly they look like age, later ones that come as the disease starts to make her feel unwell, and a short list of emergencies that don't wait, whatever her stage. Kidney failure is the older name for chronic kidney disease in cats, the same organ and the same problem, so the signs are one list rather than two.

The early signs: drinking more, peeing more and losing weight

In any older cat, more drinking, more urine, weight loss or a change in appetite is worth checking with your vet, since finding out early is always better than finding out later. None of these is an emergency on its own, but each one is a good reason to book a visit and ask for bloodwork and a urine test.

They're also easy to miss, and that's nobody's failing. Think of a cat with a covered litter box, a cat who goes outside, a cat in a house with three other cats or a cat who drinks from the bathtub faucet when nobody's watching. Nobody spots those changes reliably, and vets don't spot them by looking either, so we screen older cats with blood and urine instead: every year from about age seven, and twice a year once she's past ten.

Later signs, as the disease starts to make her feel unwell

As more filtering is lost, waste builds up in her blood, and that's what makes a kidney cat feel bad. Cats usually start to feel it around stage 3 kidney disease, and by stage 4 the signs are usually obvious. Here's what that tends to look like at home.

• Clear weight loss and lost muscle, even when she seems to be eating.
• Nausea, which in most kidney cats is silent. She licks her lips when there's no food around, swallows over and over, drools a little, walks up to the bowl and turns away, or sits hunched over the water dish. Some cats vomit too.
• A duller coat, and less grooming than she used to do.
• Weakness, sometimes in the back legs, sometimes with her head held oddly low. Low potassium is a common reason, and it's treatable.
• Tiring easily. As the kidneys stop making the hormone that drives red blood cells, she can become anemic, which is a later-stage problem and also treatable. Gums that look pale or white are a different matter, and they're on the go-now list below.
• Constipation, meaning small, hard stool or nothing for two days. Kidney cats are mildly dehydrated most of the time, so their stool dries out, and a constipated cat feels sick and goes off her food.
• A sore mouth, where she comes to the bowl clearly interested, then flinches away or chews on one side.
• Restless nights, wandering and unable to settle, especially at two in the morning.

That list looks grim written out, so here's the encouraging part. Most of those are separate, treatable problems sitting on top of the kidney disease, and treating them is most of how a kidney cat gets to feel like herself again. Nausea, dehydration, constipation, low potassium and anemia are all things your vet can do something about, and the nausea page is the place to start if she's gone off her food.

Signs that mean go now, or call today

These don't wait, whatever her stage and whatever else is going on. The first list means an emergency clinic now, because those are measured in hours. The second means a phone call today rather than Monday.

Why cats hide kidney disease so well

Kidneys are built with enormous spare capacity. A cat can lose something like two thirds of her total kidney function before her blood values move outside the normal range at all. She spends that whole stretch compensating, mostly by drinking more and passing more urine, and she does it well.

On top of that, cats are survival animals. They hide pain, weakness and illness for as long as they can, so that by the time a cat lets you see she's sick, it has usually been going on for a while. She wasn't well last month and sick this month; she was compensating last month, and now she's run out of margin.

So if you're going back over the last few months and wondering what you missed, I'd gently ask you to stop there. She was doing what cats do, and doing it well, and the fact that you're reading this now is what matters for her.

What to do if you're seeing these signs

If she hasn't been diagnosed, book a visit with your vet and ask for a blood panel, including SDMA, and a urine test. Write down what you've noticed and roughly when it started, and weigh her if you can, because a dated weight is worth more than an impression. If anything from the go-now list is happening, that's an emergency clinic tonight, not an appointment next week.

If she's already been diagnosed, the signs above are what you're watching for between rechecks. Four things, written down with a date, tell you almost everything: her weight, whether she ate, roughly how much she drank and what the litter box looks like. That routine is on the monitoring at home page.

Either way, the next step after the signs is understanding the disease itself. Start with what chronic kidney disease in cats actually is, then her IRIS stage, which is how your vet describes how far along she is. If you've just been handed the diagnosis, the seven practical things, in order, are on the start here page.