Tomcats spray urine as a means of chemical communication and to mark their territory. This activity, which may be under taken by both entire and castrated males, should be differentiated from normal micturition and abnormal urination associated with Urinary Tract Infections. When spraying, a cat holds its rump high with the tail erect and the tip of the tail quivers. Treading movements are also often seen as the spray, usually about 1 ml, is sent back onto a vertical surface in short jets. Spraying indoors may be triggered by the presence of rival cats, social upheaval (including home decoration) or the loss of human or animal companions.
Castration of entire males usually diminishes or stops spraying and makes the urine less pungent smelling. It is, however, not universally effective; rates of effectiveness have been reported to be around 78%. The administration of progestagens is sometimes effective in both entire and neutered cats. Medication can be given intermittently or continuously. The mode of action is thought to be through negative feedback on the hypothalamus and through calming effects in the cerebral cortex. The use of sedative or psychoactive drugs may also be of help in the short term, while environmental and behavior modification are introduced.
Cat owners should be discouraged from punishing the tomcat in any way after spraying, since this can exacerbate the situation. On the other hand, if the cat can be caught in the act, direct punishment (a jet of water from a water pistol) or a suitable object that, when thrown, physically disrupts the behavior, can be very effective. Cats caught spraying can also be deterred by an unexpected noise, such as that produced by an alarm or throwing a bunch of keys for example.
Source: Cat Heat Symptoms