Causes for this frustrating problem fall into two categories: medical problems and behavioral problems.
Common Medical Causes of House Soiling
More common causes are listed first. Less common causes are listed later.
- Bladder infections are the most common cause of urinating outside of the litter box in older cats. They are rare in younger cats.
- Inflammation of the bladder, known as FIC, FUS or FLUTD, may cause inappropriate urination. This is the most common cause of house soiling in cats less than 7 years of age.
- Any disease that causes increased consumption of water, such as diabetes mellitus, kidney disease, or hyperthyroidism may cause cats to urinate outside of the litter box.
- Cats with arthritis or mobility disorders may have difficulty reaching the litter box, especially if long distances or stairs must be navigated each time the cat needs to urinate.
- Constipated cats may urinate outside of the box because of excessive straining during attempts to defecate.
- Exposure to certain toxins (especially pesticides) may cause urination inside the house.
- Cats may involuntarily urinate during seizures.
- Irritation of or trauma to the external genitalia very rarely causes house soiling.
- Neurological irregularities may cause house soiling.
Common Behavioral Causes of House Soiling
- Stress is the most common behavioral trigger for house soiling.
- Many cats will urinate outside of the litter box in response to the box not being kept adequately clean.
- Cats may refuse to use a litter box in which they do not feel safe.
- Cats may refuse to use a litter box that lacks privacy.
- Cats in the house may urinate in any area that has previously been soiled, due to the odor of urine in that location.
- Elderly cats may suffer from cognitive dysfunction (senility), leading to a lapse in litter box habits.
- Urinating outside of the litter box occurs as normal marking behavior in some cats. This is especially common in male cats that have not been neutered.
- Cats may be reluctant to use litter boxes that do not provide adequate privacy. A cat may refuse to use a litter box if it has been ambushed or attacked by another cat in the house while previously in the box.
Recommended Course of Action
It is critical to determine whether a medical condition is contributing to the inappropriate urination. For that reason, any cat who consistently urinates outside of the box should be assessed by a veterinarian.
Consider neutering or spaying intact cats who urinate outside of the box.
Male cats that urinate outside of the litter box may develop a life-threatening syndrome known as urinary obstruction. Any male cat that demonstrates urinary irregularities should receive immediate veterinary care.
If a veterinarian can find no medical cause for house soiling, implement a behavior modification protocol. More information on this topic can be found in the article entitled Behavioral Modification for Urinating Outside of the Litter Box.
Copyright © Eric Barchas, DVM All rights reserved.
The contents of this page are provided for general informational purposes only. Under no circumstances should this page be substituted for professional consultation with a veterinarian.