2 Male Cats Have Stopped Using Litter Boxes

[jr70895]

I have 2 male cats both 1 year old that have stopped using the litter boxes, both neutered.
I keep the boxes clean and scoop out every time I see something in them and make sure they are clean in the morning and at bedtime. Haven't changed any food types or the location of the boxes.
Even though they go outside several times a day they've always used the inside boxes especially at nite.
I can wake up the next morning and can plainly see where they've used them the nite before.
They are not even attempting to use, not standing over them straining to go or nothing.
I have started giving the Cat Lax in an effort to see if they are constipated, but as mentioned they are not even attempting to pee or poop.
If it was one cat I would think he would have medical problems but both is puzzling.
I have completely cleaned out and washed both boxes and put in fresh litter.
I am thinking of taking both to the Vet in a couple of days to see if it is medical.

Any suggestions would be appreciated, Thanks.

 

[jcat]

Are they going elsewhere in the house (you can use a black light to search for urine), or are they now doing all their "business" outside?

 

[Ceracera]

Maybe theyre now old enough to hold it until they get outside.

 

[jr70895]

I took both cats to the vet and had them checked. Vet said nothing wrong and they were not plugged up. Someone suggested Miralax. I gave them a dose and that worked the next morning. However, that was a week ago. They haven't used the litter boxes since. I do let them out but both are back in by 4:00PM.
The next morning they go back outside for an hour or so. In the time that they are inside which is at least for 16 hours they will not use the boxes. Again, they are not going outside the boxes or anywhere in the house. Boxes stay clean and haven't changed litter or location. They are not attempting to use at all.
Just find it hard to believe they went from constant litter box usage to nothing in a months period.
Any suggestions appreciated.

 

[Snakitty]

If they are eating and drinking okay and aren't plugged up and aren't going somewhere else in the house, they are going outside just fine (it's gotta be going somewhere). It's just their preference. I had friends that had indoor/outdoor cats for years and they never used the litter pans. If they have found an "alternate" spot in the house, then you have a problem.
Careful with the Miralax. I had a cat with chronic constipation and the Miralax caused diarrhea. Prolonged use can also create a dependency. When my cat was younger, switching to a grain free food really helped his digestion. I fed him Wellness Core. As he got older (17+) his vet put him on a Fiber Response food from Royal Canin and he pooped daily no problem, it worked great.