Question on odds of new cat spraying...

In a week and a half or so, once I finish moving in, I am adopting a 2-year old half-abby from a local rescue group. Mallorn, as I've decided to call him, was previously an outdoor only cat, and was only castrated 3 weeks ago.

Now, before he was altered he was spraying up the wazoo at the rescue place, but hasn't done it since. This was one of my reservations about adopting him, but he's been good.

I'm wondering if I can expect him to start up with it again once he is introduced to my current cat, Rowan who is... er... half spayed.

Is there anything I can do to decrease the odds of him spraying?

Ok...first, what is 'half-spayed'....I've never encountered such a thing. Secondly, the spraying the shelter may have experienced was most likely before and right after his neuter. Everything I have read indicates that neutering does reduce and can even eliminate spraying behavior. Here is just one example of an article that references the positive effect of neutering on spraying behavior.

Neutering male cats stops spraying or urine marking in over 90% of cats

http://www.api4animals.org/86.htm

Rowan is only "half" spayed because when she underwent her diaphragmatic hernia repair, the surgeon removed her ovaries, but not her uterus. -_-;; The vets where I work were astounded by this and weren't even sure what to call it.

So, the odds then are fairly good that he *won't* start up again? I had hoped that him being neutered would permanently fix the problem, but then I've also yet to encounter a male that was that old before he got altered so I was unsure.

I think that if you do a careful introduction of the new cats (click here to read how) AND if you plug in a Feliway Diffuser before he moves in, I doubt you will have a problem.

Good luck!