Hello Andreea, I'm Dr. Deb.
I recently came online and see that your question about Ivan Motanski hasn't been answered. I'm so sorry that you've had to wait for a response,but if you still need assistance, I'd like to help if I can.
When cats start urinating outside of the box, this is either going to be secondary to a behavioral problem or a medical one. It's not likely that he has an issue with his kidneys at his age, although it is possible that he might have a bladder infection. However, having said that, most cats with the latter problem will inappropriately urinate more frequently than every 3-4 days.
Cats use urination (and defecation) as a means of communication although when they inappropriately urinate outside the box. it may not always be obvious what they're trying to tell us.
Psychological stress, such as the presence of other cats, prolonged absence of the owner (who is usually viewed as a parent by the pet cat), or other problems may create a need for a cat to reassert a territorial claim and thus engage in this behavior.
The cause may also be something as simple as something involving the litterbox/litter itself. When presented with patients who urinate outside the box, I always like to address this first, especially if the problem is intermittent (as in this case). Much research has been done on this topic and the following is a summary of this research:
1. Some cats like a very clean box; when it becomes dirtier than they prefer, they'll urina elsewhere. So, the box should be scooped at least daily or twice daily and the entire box cleaned weekly with soap and water; avoid harsh smelling chemicals.
2. The number of boxes and size is important: The rule of thumb is one box/cat plus one box. A litter box length should be at least one and a half times the length of the cat (not including the tail) so they have adequate space to maneuver and eliminate.
3. Cats prefer clumping litter.
4. Cats prefer unscented litter.
5. Cats don't like hoods on their boxes because they retain odors.
6 Cats don't like their boxes where there's a of noise or foot traffic; they prefer privacy.
7. Use of enzymatic cleaners to degrade the urine rather than just cover up the odor (the cats can still detect it) are preferred. If your cat urinates in one particular area more frequently, he may think that it's ok to continue to do so.
Other helpful hints in addition to the above:
1. Use of Cat Attract in the litter
2. Sometimes confinement in a smaller room/space with food/water and the litter to "retrain" them can be useful.
3. Stress can play a role in this problem as well so you might consider use of a product called Feliway, a natural pheromone which may help reduce anxiety. These products are available here in the States on the internet and most pet stores as a diffuser or spray or a collar that the cats wear. There is another product called Composure Chews (Vetriscience) which may also be useful for some cats; it's the oral equivalent of Feliway.
If the problem persists, then a vet visit may be prudent so that a urinalysis can be done.
I hope this helps and gives you some options to consider. Again, my profuse apologies for the delayed reply. Deb