One of my cats can be a naughty girl. I know when she's been bad as soon as I open the curtains in the morning - and step on wet carpet. Happily, I soon sorted the reason behind her problem: It was her version of a 'dirty' protest, because she wanted the litter tray cleaning more often. Once I understood the message, I upped my scoop patrols and she stopped weeing where she shouldn't.
There are all sorts of reasons a cat stops using her litter box, but this problem you need to correct quickly before it becomes a habit. Key to restoring good litter box habits is to think like a cat in order to find out why her toileting habits have taken a turn for the worse.
Inappropriate urination (the posh way of saying 'peeing on the carpet') is broadly due to two reasons: health problems or behavioural issues.
A Cat Caught Short
First, let's deal with health issues. A cat feels an urgency to pass urine if their bladder is either painful or very full. Either of these two things can catch a cat out and give her a sense of urgency, which mean when she's gotta go- she's gotta go.
A sore bladder is a common consequence of issues such as a urine infection or bladder stones. Likewise, cats with health problems such as kidney disease, an overactive thyroid, or diabetes mellitus (sugar diabetes) tend to be thirsty and drink a lot of water. Consuming lots of water means the bladder fills more often - with the resulting need to pee more frequently.
If you notice your cat squatting repeatedly, there is blood in her urine, or she is thirsty, it's time to get her checked out by your veterinarian.
Mindful of the Litter Box
Now let's turn our attention to the behavioural issues. We all know cats are fastidious about keeping their coats clean, and the same goes to toileting. For a cat to avoid the box is a sign that something about the box isn't right for her. So put your detective hat on and consider the following:
Number of litter trays
Urine and feces are potent signs of possession. If a cat has to share a tray with other cats, she may be intimidated by the messages they leave behind. And rather than offend her fellow house cats she may elect to toilet elsewhere... The golden rule is to provide one tray for every cat in the house, plus one spare. So if you own five cats (as I do) that's six trays, minimum!
When a cat goes to the toilet she is very vulnerable. If another cat pounced on her while she in using in the tray, she may feel insecure and wary about using it again. Take a close look and see if the tray is 'protected' so that she can use the tray in seclusion.
If you tried to give your cat her deworming medication whilst on the tray, she may now have unpleasant associations which lead to her avoiding it. Try putting the tray in a new spot (show her where it is) and stand well away when she goes to use it.
Some cats are picky about the texture of the litter beneath their paws, or else the smell (especially scented litters). If the inappropriate peeing started after you bought a new litter, then go back to the old brand. Try experimenting with different types of litter, to see if there's one she prefers.
If the cat had a fright whilst using the tray, this can make her feel it's not a safe place. One common mistake is to site the tray in a laundry room beside a tumble dryer. If the dryer happens to go into spin cycle as she's squatting that can give her a nasty surprise she won't forget in a hurry. So there we have it, a whirlwind tour of cat toileting habits, to help you avoid those 'Argh!' moments as you open the curtains first thing in the morning.