Image via WikipediaThe most common reason cats go to the veterinarian seems to be for urinary problems. This may be related to the common complaint many cat owners have that their kitties are eliminating outside of the litter box. Sadly, this behavior often results in them being thrown outside, because some people believe the cat is doing it on purpose, as a sort of revenge for something.
Cats don't have human emotions, so revenge isn't in their repertoire of behaviors. If they are having difficulty urinating, it's usually a medical problem and they should be taken to the vet to have an exam and possibly treatment. The most common urinary ailment is called Feline Lower Urinary Tract Disease, or, FLUTD. (For a list of common ailments, see my website:
If they pass their medical exam and it's determined to be a behavior problem, it's only fair to look into the possibilities with that, too. They don't have the problem-solving abilities that we do, nor do they have the authority to change things at the house! Check this list of reasons cats may not like using their litter boxes: www.theproblemcat.com/articles/elimination.html
Often, this problem can be cleared up fairly easily, either with a round of antibiotics if it's physical, or making some changes at home if it's emotional. It can be as simple as placing the litter box in a new location!