6 yr old Maltese Peeing in her Crate

Question
Hi there, our Maltese has started peeing in her kennel.  She sometimes pees in the house in other spots as well.  We've taken her to a vet, had xrays and blood work done which reveal nothing.  She is happy, and nothing, i mean nothing has changed in her routine, food or anything we can think of.

We work during the day and prior to a month ago, her and her "brother" a 7 year old chihuahua terrier cross, were free to roam their own room with water and food.  Then one of them, we weren't sure which one, started peeing in the room.  We have always crated them at night, toghether, so we started crating them during the day.  Then we noticed the pee in the crate too.  So we've separated them and she still pees in her crate or in the room if we've left her out.  

Any ideas how to get her to stop this behavior?

Answer
Is your female dog spayed?  It could be that she has a relaxed sphincter, which means that she could be leaking urine when she sleeps.  Sometimes this is called "spay incontinence". It wouldn't show up as an abnormality on tests, but sometimes worsens as a female dog ages.  There are medications that can be used, so speak to your vet again about whether he/she thinks this may be a possibility.  Also, consider that a change in the dog's environment may have occurred and yet isn't obvious to you (maybe some construction in the neighborhood etc.)  That can change a dog's routine or make them regress in house training skills.  In case this is marking behavior, be sure to clean any mistakes with an enzymatic cleaner (Petastic, Nature's Miracle, etc.) If you can't find any cause, the normal solution is to go back to house training 101, as if both dogs were puppies.