How on earth do I deal with this? Dog suddenly peeing up things.

[BumbleBeeWineGlass]

I have a 3 yr old Chihuahua, male.
He was housetrained easily as soon as we got him, he's never used the indoors as a toileting area.
We have a disabled child with a lot of medical equipment that needs to be clean and sterile, it was because the dog was so reliable with his toileting that we got the go ahead to keep him from DS's consultant.

Anyway, when we go away we leave the dog at home and ask BIL to stay to feed/walk/keep company because the dog doesn't like other dogs so we felt a kennel isn't right for him.

Last time we went away we came back and BIL said he's had awful problems with the dog as he's started peeing up the curtains, bookcases and the sofa.
He's a tiny chi so doesn't usually cock his leg to do a full wee but this is cocking the leg and almost scent marking, always the same 3 places and now the house STINKS!
If it continues I can see DS's healthcare team saying he has to be rehomed which I don't want to do.
Anyone have any ideas? I can remove the curtains and I've scrubbed those patches with bleach but it's still happening.

Bleach won't stop it happening - you need a proper enzyme remover specifically designed for pet urine - you can get it in pets at home.

Is your dog neutered? That generally stops marking behaviours.

No he's not neutered, I was just about to call the vets to ask advice if that might stop it.
I will get an enzyme treatment for the floors too.

Does anyone know anything about the plug in things for calming animals?

Scent marking is the only behaviour that might be improved by neutering - how old is he?

He's 3

Sorry I see his age in the original post(!) in a rush
,
Yep I would speak to the vet about castration and also rule out a urine infection.

The plug in adaptil can work for some dogs but others make no difference at all, could be worth a try

At three I really think you should consider neutering. There are plenty of health benefits and it's been shown to stop marking behaviours.

I will get it sorted ASAP.

Neuter, that will stop marking, it will also prevent the very embarrassing situation that we found ourselves in when we had a house full for a dinner party and our lovely young boy decided to have a full on fantasy, including ejaculation, under the dinner table 😂 😂