I got my sisters cat about 2 weeks ago he started of fine personally

• Litter Box Aversion – Consider whether you’ve changed the litter box recently. Litter boxes need replaced every so often, because the uric acid gets into the plastic (even if you use a liner and deodorizing sprays). When you replace the box, it is important to use the same type of box you’ve always used. The depth and size should be the same. If the old litter box had steps, the new litter box should have steps. If the old litter box had a cover, the new litter box should have a cover. If you have not changed the box, the cat may still have developed an aversion to that particular box. Experiment with different shapes and styles (covered and uncovered). If your cat is particularly large, she may need a bigger box. Kittens often outgrow their first litter box rapidly.
• Fear – There are times when cats develop a fear of the litter box. There are several reasons why a cat might become afraid. If there are multiple cats in the home, one cat may be waiting on the other to come out of the box and pouncing. Whether it is done playfully or as a territorial move, such moments can frighten your cat and keep her from using her box. Dogs sometimes startle cats as well. If you have other pets in the home, watch closely and see if this is occurring. If so, then move the box to a new area where the cat can do his business in peace.
• Dirty Litter – Some cats are particularly finicky about their litter. If it is soiled at all, the cat may not use it. In homes with more than one cat, you should set up more than one litter box. Put everyone in the family on pooper scooper duty. The litter box should be cleaned out several times a day and a fresh layer of litter added every couple of days. There are some automated litter boxes on the market, but they can be costly and some cats are scared of them as well. If you decide to purchase an automatic litter box, be sure you can return it if your cat doesn’t take to the system.
• Type of Litter – Consider what type of litter you are using. Some cats prefer very fine, scoopable litter and others like a coarser litter. If your cat has been declawed, his paw pads may be tender and coarse litter could be the culprit. Some litters also have heavy perfumes that are a turn-off to cats. Trying different types of litter is an excellent way to see if the litter is the reason your cat is urinating outside of the box and is an expensive solution. When changing cat litter, start with a mixture of 75 percent of the old litter to 25 percent of the new litter. Use that combination for a few days and then switch to 50 percent of each. Continue changing every few days in 25 percent increments until the box has 100 percent of the new litter. Do this each time you change litter brands or types.
• Household Changes and Stress – Major changes in the household or stress can cause a cat to feel confused and to not use the litter box properly. Divorce, a death in the family, new family members moving in and new pets introduced to the home can all cause stress on your cat. A neighbor with new dogs that bark constantly can also unnerve your cat. Moving to a new home can also cause stress. If the home is not new, then pets that have lived in the home before may have left behind scents that will frighten and confuse your cat.
• Marking Territory – One common reason for peeing in inappropriate places is to mark territory. If you’ve lived with a cat for more than a few minutes, you probably realize that they are territorial. Cats seek out their favorite spots and return to them time and again. In a house with more than one cat, each cat may seek to mark his territory by urinating or spraying. Spraying is an entirely different issue with its own set of problems, but is usually cured by neutering your male cat. Solutions include making sure each cat has its own box in a separate area of the house, keeping a separate bed and separate food dishes for each cat. If you have more than two or three cats, this can be a real challenge, so you may need to simply isolate the cat with the urination problem and give him a space of his own.
• Separation Anxiety – Another possibility is that your feline has separation anxiety. People often get cats because they are a pet that can be left alone for longer periods than a dog. Cats don’t need walked and many people assume they don’t need a lot of attention. While a cat may not require as much one-on-one attention as a dog, felines still crave interaction with their human companions. If you work long hours or have been away from home a lot, your cat may be experiencing separation anxiety, which leads to stress, which can lead to inappropriate urination.

Once you’ve read through the common causes above and narrowed down the cause of your cat’s behavior, take the following steps to try to end the problem once and for all.

1. Thoroughly clean any areas where the cat has previously urinated. (see Cleaning the Pee Stains below)
2. Replace anything that needs replaced, such as the litter box or brand of litter. If the cat likes to pee on a particular rug in front of the box, remove the rug or replace it with a new one.
3. Try to catch your cat using the box and praise him. Cats respond best to positive reinforcement.
4. If the cat continues to urinate in the wrong spot, isolate your cat with the litter box in the smallest space possible, but as a bathroom or laundry room. Leave your cat in this room with her box for a minimum of one week. Go in to clean the box and give him attention, but the cat stays in the room with the litter box. Ideally, this is also the area where the box will remain.
5. After a week, allow your cat to wander into the rest of the house, but watch very closely. If he starts to urinate outside of the box, firmly tell him no and carry him to the box. Praise him as you place him in the litter box and leave him in the room with the box for a few more days.
6. Repeat as necessary.
7. Be patient. It may take weeks to retrain your cat to use the box, especially if he has had a traumatic experience of some sort.