Change in cat behavior

Question
I have two cats - both adopted from shelters at different times when they were about 5 months old.  We've had the oldest, which is a wonderful people cat, for about five years now.  I believe its our favorite that has started pooping periodically on the guest bed and one of my daughters beds.  She hasn't done this on anyone elses bed.  About 2 months ago, we did have a stray kitten in the house for about 3 weeks, which has since been adopted out.
I do clean the cat boxes (2) at least every other day.  Do you think this is behavioral towards that one daughter or do you think I should bring her to the vet?  Thanks so much!

Answer
To be honest, cats almost never urinate or defecate outside the box due to behavioral problems. People (including vets) used to conclude this a lot in the past, but it is becoming easier to test for medical problems and now we know that most of the time the cat is doing it due to pain or discomfort.

Always the first thing to rule out is medical issues. Constipation, parasites, food allergies and more could cause him pain or discomfort which she expresses by avoiding the litter box. Also some cats do this when they have urinary tract problems - they feel pain when they urinate, so they associate the litter box with pain, but they are too conditioned to pee in the litter (and don't like the splashing of their legs, but they don't want to go in the "place of pain" unless they feel they absolutely have to.

So, first is a trip to the vet for a full exam and:

1. get the vet to take a urine sample by cystocentesis and do a urinalysis
2. bring a fresh (< 12 hours) fecal sample to check for parasites
3. get a complete blood panel including thyroid

If all the above results are normal, think about what might have changed - her diet?

You can also try Cat Attract litter, it contains a herbal attractant that helps attract cats to the litter and it does work - but if there are medical issues it of course will not solve that. It is sold at Petsmart and other stores http://www.preciouscat.com

Also this article contains useful information:

http://catnet.stanford.edu/articles/litterbox.html

Did you add a litter box int he room in which she is defecating? Does she ever get closed in there by accident?

Finally, I would exclude your cat from the room that she is defecating in, until the habit is forgotten she may continue to do it.