Cat Drinking More Water Than Usual? A Vet Nurse on the Warning Sign Most Owners Notice Months Too Late
If you're filling the water bowl twice a day and the litter clumps have got bigger, this isn't a good sign she's staying hydrated. Here's what it usually means.
It starts so quietly you'd never call it a symptom.
The water bowl you filled last night is empty by lunchtime. You top it up. You find her sitting in the empty bath, staring up at the tap, waiting for a drip. The clumps in the litter tray are bigger than they used to be. Much bigger. You're changing the litter twice as often and you've started buying the large bags.
And you think, well, at least she's drinking. Water's good for her. Everyone says cats don't drink enough.
I spent twelve years as a vet nurse in a clinic with a heavy feline caseload. I want to tell you what I learned about the water bowl, because it's the most common early warning I ever saw, and almost every owner I met had been looking at it for months before they said anything.
"I Thought She Just Liked the New Fountain"
That's the sentence I heard more than any other.
The owner would be sitting in the consult room. The vet would have just explained the blood results. And the owner would say, very quietly, "She's been drinking more since about winter. I thought she just liked the new fountain."
Or, "I thought it was because it's been hot."
Or, "But she's eating fine. She seems fine."
One owner I met did it differently. She noticed the water bowl, and she didn't wait. Her cat was called Bella, and I'll tell you what happened to Bella further down, because what her owner did in the six months after that appointment is the reason I'm writing this.
Here's what I wish every one of them had been told a year earlier. In a cat over about ten years old, a noticeable increase in drinking is one of the most important things you can ever see. In most cases it's her body working harder to make up for something.
You're not the only one who's seen it, either. In one large survey of owners of cats aged eleven and over, more than four in ten said their cat was drinking more than it used to. It's one of the most common changes in older cats. That's exactly why it gets waved away.
What the Extra Water Usually Means
There are three main reasons an older cat starts drinking more. Your vet will want to check all three, because they're treated very differently.
The only way to know which is a blood test and a urine test. So before you read another word, if your cat is over ten and drinking more, please book that appointment. This week, not next month.
Now I want to talk about the first one, because it's the one I saw most, and it's the one where the next six months matter most.
Why Tired Kidneys Make a Cat Thirsty
One of the kidneys' main jobs is to hold on to water. Cats evolved from desert animals and their kidneys are brilliant at it. A healthy cat's kidneys pull water back out of the urine and send very little of it to waste, which is why a healthy cat's urine is so strong.
When kidneys start to lose function, that's one of the first abilities to go. They can't concentrate the urine any more. So more water pours straight through and out into the litter tray.
She's drinking more because she's losing more, and she's trying to keep up.
And here's the part that frightened me most when I first understood it.
By the time standard blood tests for kidney function start to rise, a cat has typically already lost around three-quarters of her working kidney function. The kidneys have a huge reserve, and they quietly use it up before anything shows. A newer blood test called SDMA can pick up the change earlier, at roughly 40 percent loss, which is why it's worth asking your vet to include it.
So by the time you notice the water bowl, this has usually been going on for a while. That's exactly why you book the test this week.
Measure It Before the Appointment
Here's a simple thing I used to tell owners. It takes one day and it gives your vet a real number instead of "she seems to drink a lot."
Cats on wet food drink less from the bowl than cats on dry food, because they get water from their meals. That's normal. What matters is a change. If she's on the same food she's always been on and she's drinking noticeably more, that's the signal.
"It's Early. Let's Recheck in Six Months."
If the bloodwork does show the start of kidney disease, there's a phrase you'll quite likely hear. I heard vets say it hundreds of times, and they're not wrong to say it.
"It's early. Stage one or two. Let's recheck in six months."
Most owners walk out of that appointment relieved. And then they go home and do nothing for six months, because nobody told them there was anything to do.
I want to be honest about this. Nothing reverses kidney disease. The damaged parts don't grow back. But cats diagnosed early can live for years, sometimes many years, and the speed at which the remaining kidney function wears down is not fixed. Those six months are a window, and most owners spend them waiting.
Those six months are a window. Most owners spend them waiting.
What Wears Kidneys Down
Kidney disease in cats is a slow, grinding process. One of the main things driving it is inflammation inside the kidney itself, and the pressure on the tiny filters that do the work. Each filter that's lost puts more strain on the ones left over, and the cycle keeps turning.
This is where the research on omega-3 fats comes in, and it's one of the few things outside of prescription medicine that has real evidence behind it in kidney cats.
The two omega-3 fats in fish oil, EPA and DHA, help calm inflammation in the body's tissues, including the kidneys. In a study published in the Veterinary Record, researchers looked back at cats with kidney disease that had been fed different prescription kidney diets. The diet with the highest EPA content was linked to the longest survival times.
to inflammation & pressure
weak, watery urine
more water lost
to keep up
Fewer filters left means each one works harder. Omega-3 helps take the heat off.
That's a big part of why the prescription kidney diets your vet may recommend now have fish oil added to them. It's there on purpose.
The problem is the next bit.
Why So Many Kidney Cats Never Get Enough of It
In the clinic, the same three things got in the way, again and again.
She won't eat the kidney food. Prescription renal diets are lower in protein and phosphorus, and many cats find them bland. Plenty of owners told me their cat ate it for a week and then went on strike. If she won't eat it, she isn't getting the fish oil that's in it either.
The capsules smell. Owners would buy human fish oil capsules and squeeze one over the food. Most cats sniffed it and walked away. A cat with tired kidneys can already feel a bit sick and off her food, and a strong fishy smell is the last thing that helps.
The oil goes off. This is the one nobody thinks about. Once a bottle of fish oil is opened, air gets in and the oil starts to oxidise, which means going rancid. Cats can smell it long before you can. And oxidised oil can add to the very inflammation you're trying to calm.
So when owners asked me what I'd actually do, I gave them a short list.
- Fish and krill oil, not a plant oil like flaxseed. Cats can't make good use of plant omega-3.
- Sealed, single daily doses, so it's fresh every time and never sitting open going stale.
- A flavour she'll actually eat, on whatever food she will eat. A kidney cat who eats is a cat with options.
- Easy enough to give every single day, because the benefit builds up over weeks, not days.
The one I came to recommend most was a snap-pack made by a company called Fureeze. It's an Australian company (they also ship to the UK and US, and it only takes about 5 days).
What It Is
Each box holds daily snap-packs of fish and krill oil. Each dose hasn't touched the air until you snap it. You squeeze it over her food. There's no bottle on the bench going off, and no capsule to pierce.
- Fresh every single day. Each dose is sealed until you snap it, so the oil never sits open going rancid
- EPA and DHA from anchovy and krill oil, the two omega-3s cats actually use, guarded by vitamin E and astaxanthin
- Mixes straight in. Emulsified, so it blends into wet or dry food instead of floating on top
- Chicken flavoured, so cats that sniff at capsules eat it
- No fridge, no pump bottle, no measuring. One snap-pack a day from the cupboard
The oil is anchovy fish oil and krill oil, protected from going off by natural vitamin E and astaxanthin, the antioxidant that gives krill its pink colour. It's emulsified, so it blends into wet or dry food rather than sitting on top.
And the flavour is chicken. For a kidney cat whose appetite is already fragile, that matters more than anything else on the label.
I watched a lot of fussy older cats try it. Most of them ate it like a treat. That's the whole game with a kidney cat: a fish oil she'll eat, every day, on the food she'll eat.
What Bella's Owner Did
One case stays with me. I've changed the details, but the shape of it is true to so many I saw.
Bella was a thirteen-year-old tortoiseshell. Her owner, a retired nurse herself, came in because the water bowl "wasn't lasting." She'd measured it, like I describe above. Bella was drinking more than twice what she should.
The bloodwork showed early kidney disease. Stage two. The vet put Bella on a plan: a kidney diet if she'd eat it, regular blood pressure checks, a recheck in six months.
Bella wouldn't eat the kidney diet. So her owner kept her on her normal wet food, as the vet agreed, and added one thing: a fish oil snap-pack squeezed over every breakfast.
Bella's kidneys didn't get better. That's not how it works. What her owner bought with those six months was time, and a cat who kept eating. With kidney disease, that's what winning looks like.
The Questions Owners Ask Me
"Should I start this or see the vet first?" See the vet first. Please. Increased drinking in an older cat needs bloodwork, because it might be her thyroid or diabetes, and those need their own treatment. But don't wait for the next recheck to start protecting what's left of her kidneys.
"She's on a kidney diet already. Does she still need it?" Many kidney diets contain fish oil, but only if she's eating a full portion every day, and many cats don't. A snap-pack means you know exactly what she's getting.
"She's drinking more but her bloods were normal." Ask whether SDMA and a urine test were included, and ask when to repeat them. Normal results are good news, but keep measuring the water bowl.
"Will she eat it?" Most cats do, because it's chicken flavoured. Squeeze it over a food she already loves for the first few days.
What Owners Have Said
These are real reviews from verified buyers of the same snap-pack.
Our cat Oscar is 17 years old. He is absolutely thriving on Fureeze krill oil supplement. He's livelier, glossier and rejuvenated. I can absolutely recommend Fureeze.
My 17 year old cat seems to be enjoying the addition to her dried senior diet. Hopefully it is helping to keep her well and healthy. Her fur certainly seems softer.
My senior cat, Larkin, loves the taste of the fish and krill oil supplement. She is a fussy cat who will refuse to eat some canned food and even some cat treats.
Soooooo much better than the glass bottle of fish oil and the dropper that falls apart before you're ready for a new jar and no matter how much you rinse it, leaves fish oil residue anywhere near it. My picky eater loves the taste and he was never super fond of the most expensive omega oil brands out there!
If You're Refilling That Bowl Twice a Day
Please don't do what so many owners told me they'd done, and wait. Every month of waiting is a month of filters you don't get back.
Measure the water tomorrow. Book the bloodwork this week, and ask for SDMA and a urine test. And whatever the results say, give her something every day that helps the kidneys she has left.
Fureeze has an offer on for new customers at the moment.
It's covered by a 90-day money-back guarantee. Give it 90 days. If you don't see a difference, send back the empty box for a full refund.
The water bowl is the first thing she can tell you. I hope you're listening early.
Kayla
P.S. Bella's owner did two things the week she noticed the water bowl: she booked the bloodwork, and she started a fish oil Bella would actually eat. Six months later the kidney values hadn't moved. If you're refilling that bowl twice a day, check the Fureeze offer here and give it the 90 days.