Urine marking is a primal urge, but if you have trained your cat to use the litter box, and it continues to mark the home or squat and urinate any place except the litter box, there may be something else going on. For example, the cat may not be satisfied with the litter box (i.e., its location or its environment) or it may have kidney stones, which is associated with painful urination.

Inappropriate urination can occur in any age, breed, or gender, and urine spraying is more common with males than in females. Spraying around doors or windows might be a marking response to the presence of a cat outside. Marking in the home may be a response to another cat, either in the home or outdoors. Also, due to competitive behaviors, the probability of urine spraying indoors is directly proportional to the number of cats in the household.

Causes

You should also consider the possibility that there may be a physical cause for the behavior. Following are some possibilities:

• Liver disease
• Hyperthyroidism
• Urinary tract stones
• Excessive glucose in the urine (diabetes mellitus)
• Lower urinary tract disease, including inflammation of the bladder (cystitis)
• Old age (neurological issues that are due to senility)
• Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV)
• Recent medical treatment

Some environmental/behavioral factors to consider:

• Is there something about the litter box itself that might be a problem for the cat?
• Is the box cleaned frequently? 
• Not enough boxes. A box for every cat plus one is recommended.
• Location of the box. Is it remote or is it in surroundings that are unpleasant? Is it in a location where dogs or children might interfere?
• Type of box. If it is covered, it might hold odors that repel the cat, or it might be too small for a big cat to move around in as it wants to. Also, a covered box makes it easy for other cats, dogs, or children to target the cat as it exits.
• Time factors. If there is a daily or weekly pattern of inappropriate urination, the cause is probably environmental. If a cat that has always used the litter box suddenly begins to urinate inappropriately, it is probably a medical problem.
• The litter itself. Tests indicate that most cats prefer unscented, fine-grained litter. If the cat’s habits change when you change the litter type, there may be an association with the new litter. If the cat shifts from the litter box to another surface, such as a porcelain sink, a lower urinary tract disorder may be the culprit.
• Location. Urination outside the litter box may suggest a location preference or social factors. Try moving the box.
• Social dynamics. Social conflicts between cats may affect urination behavior. Also, a change in the cat's social world, such as the addition of a new cat, may be behind the change.

If none of the solutions you are attempting are succesful and if you are unsure what seems to be the underlying cause of the house soiling, consult your veterinarian as it may be a health-related condition.