Cats can mark out of their boxes for several reasons.

unclean box, smell of other animals in their space, urinary tract infections, but the big one is stress. Cats can become stressed so easily.

Here is what I reccomend that you start with.

Strip out the area and CLEAN it well with a urine remover cleaner. Amazon and so on has many great products.

#1 get a NEW box. Dont just clean the old one. Make sure you have at least 4 boxes in your home. ONE box for 5 cats is just too few. it sets them up for competition, and marking. Put them away from each other and out of the public areas such as the kitchen or the hall where folks can watch them urinate. They, like us want to be hidden from view when we tinkle.

#2 use an UNscented litter. Petco sells a good product that is scoopable, and easy to use and keep up to. Cheap too!

I use a product called Feliway. its a pheromone that is secreted by the momma cat to her babies and its very calming. So, if they are stressed about another animal smell, it will help them relax and not feel as if they need to protect or mark the area. It can take a few days to start working, but on really stressed animals it can work within minutes. They sell a plug in, like an air freshener. A spray that you can spray on the area that is affected by urine, or a collar that they can take with them everywhere, and stay calm, even out of sight of that spot.

http://www.amazon.com/Pack-Feliway-E...1427486&sr=1-9

Over crowding, into one litterbox or even 2 boxes with that many cats can be upsetting. Cats are very clean, and dont want to pee on top of someone elses pee.

Stress in the house can also cause behavior issues (i know you and hubby have been struggling lately) and the pheromone would be helpful there too.

Do you have a place for your cats to climb in the house? a tree house? a ledge? a high window? a shelf? top of a bookcase? Cats are tree dwellers and love to climb up high to relax and unwind. If they are forced to stay on the ground where the dog smell is, it may keep them stressed. Help them find a way to get up off the ground. Mine hang out on top of the kitchen cabinets, or on a tree house. Its a great place to go destress, and it only smells like them.

If you are leaving this house, dont bother replacing carpets and wasting money on a place you are not staying in. If you are going to give it another go, and decide to stick it out again, then it may be worth the investment to at least pull up the rug, even if you are just exposing the sub floor. At least it wont be full of dander, wee, and mold anymore.

I hope that helps.