Vegas...He has been trained to go in a certain area so we don't have worry about hitting landmine when we're playing ball in the rest of the yard. He was doing fine for a long time and it just stopped suddenly, so it tells me something is wrong. He's going in different places if we don't watch him so it's not like he's found a better spot.
Franksmom, the area is cleaned every week and it's a good size area he can go in, about 20 yds long by 5 yds wide. Now, you do mention a couple things I hadn't thought of... other animals using the area. We have coyotes too, but they would have to jump a 6ft fence to get in. Not impossible, so I will take a closer look for other "users". My daughter is studying to be a vet tech so we'll crack open her books and see if the behavior is indicative of UTI for a dog.
Also going to disinfect the area to see if that helps.