They need to see a vet to rule out medical problems.

Frequently when a cat stops using it's box there is a urinary tract problem.

Lisa

I agree with Meg. Litterbox avoidance is a common symptom of illness in cats, esp. urinary tract infection and/or urinary crystals. Your first step is to take them to the vet for an exam.

Laurie

neglected to mention both cats have seen the vet and are healthy....would be odd for them both to get UTIs at the same time too,,,,does the spray work??? I am wondering if it is a behavioral thing,,,,we do have a new baby in the house,,,maybe they feel "dis placed"???????

It could very well be behavioral. We just got a new puppy. I thought he was managing to poop in the corner of my bathroom near the litter box. But then I discovered it was one of my 3 cats. Box was cleaned and they were all just in for their yearly check-ups. So I used one of Riley's piddle pads in the spot (after cleaning the spot carefully). I also started giving them extra special attention -so far that seems to be doing the trick. It's taken some time though.

try using two seperate boxes.

Cats often avoid their litter boxes when they feel stressed. After the vet exam, which you did I would put Rescue Remedy in their water. You can get it at most health food stores. I would also use Feliway a Feline facial pheromone, I would spray it in the areas the cats like to hang out in. I would have toys they like and make time to have play with them.
Rescue Remedy and other flower essences: The principle behind healing with flower essences is similar to homoepathy. Each flower has a vibrational imprint that when ingested causes the cells in the body to vibrate at that same level. It is a hard concept to understand and hasn't been proven by science. I have used Rescue in many situations and I am still shocked at the differance it has made.
Feline facial pheromones: Cats have glands in their cheeks that secrete a pheromone, they use this scent to mark what is theirs and the smell geves them a sense of security and relaxation. Cats don't tend to spray, scrach or urinate when they this scent is present. Feliway is alot like aromatherapy for cats.

Are you saying that you took both cats in to the vet specifically for this issue? Or that they recently had their check-ups and were fine before this problem came up? I wouldn't be comfortable advising you unless you have taken both in specifically for this, as they could have both eaten something and have come up with a physical issue that a check-up would not have revealed if it took place before this problem became evident.

Did the vet specifically do a urinalysis or was it for routine stuff. Generally they won't do a urine check unless you mention a problem. Otherwise it could be stress.

Lisa