When Good Cats Go Bad

Behavioral, medical, environmental reasons for soiling

We love our cats, but when one of them pees or poops outside the litterbox, it is easy to get frustrated. Cats eliminate inappropriately for many reasons, but with a little detective work and some help from your veterinarian, you can usually figure out the cause of your kitty’s indiscretions.

“The most common house-soiling cases that I see are due to litterbox aversion (i.e., some aspect of the box or litter is not acceptable to the kitty), substrate or location preference, or anxiety/social conflict,” says Pamela J. Perry, DVM, PhD, Behavior Resident at the Cornell University College of Veterinary Medicine. “I also see cats with medical problems contributing to the behavior as well as geriatric cats who are at higher risk of house soiling due to cognitive decline or accessibility issues. Many of the cases, however, involve a combination of factors.”

The Perfect Box

If your cat appears happy and healthy, one of the first things to do when he starts urinating or defecating outside the litterbox is to consider the litterbox itself, especially if you just got a new one or are trying a new litter. Several factors contribute to creating the perfect litterbox for your picky pooper:

Number of boxes. The ideal number of litterboxes is one for each cat plus an extra. This ensures that every cat has access to a litterbox and that the boxes don’t get too gross too quickly.

Location. Cats like privacy, but they also don’t like to be cornered. Convenience is a factor. The ideal location for a litterbox for most cats is a spot in the house that is not too busy but where they can’t be cornered while taking care of business. Have at least one litterbox for each floor of your house, especially if you have a tiny kitten or a senior cat who can’t handle a cross-country trek to get to the loo.

Size. Remember that your cat has to fit in the box! A general recommendation from the American Association of Feline Practitioners (AAFP) is to choose a box that is 1½ times the length of your cat (not including his tail). If your cat tends to get urine or feces just outside the box, he may need a larger box to allow him to position properly.

Style. Covered litterboxes appeal to many of us, but your cat may or may not agree. Some plastics may have an odor that is unpleasant to cats, especially when brand new. Robotic self-cleaning litterboxes may have a learning curve.

Type of litter. The AAFP recommends soft, unscented, clumping litter for most cats. Dusty and scented litters may irritate your feline’s nose, and no one wants to pee while sneezing.

Cleanliness. Be honest: Are you doing your part? Check your litterboxes at least daily to remove any urine and feces. Cats like to be clean, so they may choose their own bathroom spot if the litterbox is chronically full. If you have multiple cats, your felines may have different litterbox preferences. Experiment to see what each cat likes so you can keep everyone happy.

Social Struggles

Cats who get along well will likely be fine with sharing their litterboxes, but other cats don’t share that sentiment. If one cat gets picked on by another, be sure that the bully doesn’t block access to the litterbox. This may not always be obvious. The more dominant cat even just lounging in the hallway that leads to the litterbox may be enough of a deterrent for a timid cat. See “Managing Rival Cats” in our December 2019 issue for more information, available at catwatchnewsletter.com.

What You Can Do

  • Pay close attention to when and where your cat eliminates outside the box
  • Clean up messes promptly to remove any residual scent
  • Avoid ammonia-based cleaners, as these can smell like urine
  • Make sure you have enough litterboxes for your cats
  • Try a different box style, location, or size (larger is usually better)

Choose an unscented litter that doesn’t get dusty


“Marking behavior in cats is a form of communication,” says Dr. Perry. “We see it in household cats as a means of marking their territory. Cats also will spray when they feel threatened or stressed.” Intact cats are the most likely to mark their territory, but spayed and neutered cats also can show marking behavior. And cats may use stool to mark.

Dr. Perry recommends, “Owners should identify the trigger for the cat’s marking (e.g., the presence of outdoor cats seen through a window) and work to resolve it. If marking is related to the presence of another household cat, then owners should address the cats’ relationship.” Where your cat sprays provides clues for the cause. If your cat is unhappy about a stray who is hanging out in your backyard, he may mark near the doors and windows where he sees the other cat as a warning to stay away.

If the urine or stool is throughout the house, particularly in spots where one or more of the cats spend a lot of time, it is more likely to be due to issues between your cats. “Seeking the advice of a veterinarian, especially one who specializes in behavior, is warranted,” says Dr. Perry. A behavior consult should include an extensive discussion of your cat’s behavior and how he interacts with your other cats to give the behaviorist a complete picture so she can determine what is causing your cat(s) to mark and the best way to solve the issues.

Urinary and Gastrointestinal Issues

Urinary tract infections and disorders often cause your cat to urinate more or to feel more urgency to urinate. Parasites and gastrointestinal disorders can do the same for your cat’s bowel movements.

As well as accidents, other signs of a urinary issue include frequent urination, small amounts of urine, excessive urine production, bloody urine, gritty urine, and straining. Other symptoms of gastrointestinal illness include bloody diarrhea, frequent soft stools, hard dry stools, blood in the stool, tarry stools, infrequent defecation, and straining. If you notice any of these signs in your cat, contact your veterinarian immediately.


Senior cats may not be able to get to or use the same litterboxes they liked as young cats. A lower lip can make the litterbox more accessible. Be sure that he has easy access to a box without using stairs. Cats with cognitive dysfunction may have trouble remembering where the litterbox is, so the may need to be confined to a space with the box.

Bad Habits

“Some cats who have an underlying medical issue that contributes to house soiling may continue to eliminate outside the box after the issue is resolved,” says Dr. Perry. “This may be due to a developed preference for another location or substrate or because of a negative association (and subsequent aversion) with the litterbox.”

Your cat may associate painful elimination with the litterbox itself, or be fearful of a location where medications are given or another cat frequently ambushes him. Switching to a new box that looks different or moving the box to a new location may help. If he seems to go in a certain spot, put a litterbox in that location for him if possible to get him back in the habit of using a box.

The best way to prevent inappropriate elimination from becoming a habit is to address it promptly to resolve any underlying health or behavioral issues. Swift diagnosis and treatment will get your cat back on the right track quickly.