The causes behind your cat peeing outside the litter box

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If you find your cat peeing in inappropriate places, you are not alone. This is the most common behavioural complaint of cat tutors. Causes for this behaviour can be attributed to different stimuli in the cat environment. However, clinical problems are also an important cause for a cat peeing in inappropriate places. Thus, the first step in solving this behaviour problem is to rule out any medical cause. Only then should purely behavioural causes be considered.

The ideal litter box!

Reasons for a cat peeing outside the litter box may be related to the box itself. In this case, you may find urine on horizontal surfaces in similar amounts to that of normal urination. Possible causes for this behaviour include the type and size of the box, the substrate used, and the location of the box. In addition, frustration and stress can also influence urinating outside the box.

If you find your cat peeing frequently outside the litter box, consider the following causes:

– Insufficient number of boxes. The number of boxes should be equal to the number of cats at home plus 1 (eg 3 cats = 4 boxes).


– Box location. The box should be located in quiet and not very busy areas. Also, they should be away from the food/water bowl.

– Type of substrate used. Most cats prefer soft, porous substrates such as sand or soil, although some cats may have other preferences. The substrate layer covering the bottom of the box should be at least 3cm high. Sudden changes in the brand of substrate you use may cause aversion to the box. When in doubt, you may have two or three boxes with different substrates so you can understand your cat’s preference. Most cat dislike scented substrates.

– Box cleaning. Cats have a sharper, more sensitive sense of smell than us humans. Cleaning the box with strong-scented cleaning products can prevent your cat from using the box. Also, it is important to clean the box (collect urine and faeces) at least once a day. Most cats avoid using dirty boxes. The box should be washed every 1-4 weeks with soap and hot water.

Untitled-design-17– Box size. Many of the standard sized boxes may be too small for larger cats. The ideal box size should be one and a half times the cat’s body length (from the tip of the nose to the base of the tail).

– Type of box. Studies indicate that cats do not show a true preference between open or closed boxes. Preference is more related to how often the box is cleaned. For this reason, open boxes are preferably recommended as they are more easily monitored by the tutor, encouraging frequent cleaning.

A territorial problem …

It is important to identify the type of behaviour associated with a cat peeing outside the box. Urine spraying is the deposition of small amounts of urine on vertical surfaces and is consistent with territory marking behaviour (this is different from urine elimination behaviour). However, occasionally the cat may also mark territory with small amounts of urine on horizontal surfaces. In both cases of territory marking, the urine has a characteristic strong odor and the amount is usually small.


Urine marking may be sexually oriented. Both males and females use sexual marking to signal their presence and availability. It is normal for sexual marking to be accompanied by vocalisations. Neutering, dramatically reduces sexual marking behaviour. However, approximately 10% of male cats and 4% of females continue to exhibit this behaviour after neutering.

In addition to sexual marking, cats also mark the territory in response to environment stimuli. The presence of other cats in the vicinity, either on the street (sighting cats outdoors) or inside the same house, can trigger this type of behaviour. In addition, cats also mark the territory if they feel threatened or stressed. Stress can be caused by routine or home changes, changing house layout or other social changes (new people or animals).

A behavioural or a medical cause?

Any cat that is sick can show behavioural changes. Urinating outside the box may be one of these changes.

There are actually several diseases that can cause the cat to urinate out of the box. Therefore, ruling medical causes out should always be the first step in understanding the cause of this type of behaviour.

Untitled-design-19In the presence of a house soiling problem, your veterinarian may order several tests to rule out urinary tract problems. In addition, diseases such as diabetes mellitus, hyperthyroidism, arthritis, orthopedic diseases, cancer or feline idiopathic cystitis may also be associated with inappropriate urination behaviour.

Some of these diseases can cause pain when urinating and will cause the cat to associate the box with pain, and consequently avoid it. If there is a disease that causes an increase normal urine output, the cat may choose to urinate elsewhere simply because it considers the box to be dirty.
Disabling conditions such as arthritis, muscle weakness, and vision problems can impair the ability of elder cats to reach the litter box. Particularly if it is located far from the cat’s main territory (in a basement for example) or in poorly visible places. It is also important to consider the type of box used in these cases. For example, cats in pain may have difficulty entering boxes with high sides.

Remember: behavioural changes in your pet may have a clinical cause. Always consult your veterinarian to rule out clinical causes first.


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