He urinates everywhere, He’s always urinated everywhere. No,

Hello, you are through to Dr Linda, a UK based vet.I'm sorry to hear this and appreciate your concern for Arlo.When did this begin?Has he been neutered?

Thank you.Has he ever had his urine analysed for crystals?Does he live with other pets?

Thank you, ok.Does he go outside?How many trays do you have?

Thank you, understood.And his urine is never cloudy or bloody?Does he ever pee in drips and drops?

Thank you, ok.I'm just typing my full reply now which will take a few minutes.

As Arlo hasn't his urine analysed, this is the first step.It's quite possible he has urinary crystals, bladder stones or a grumbling infections. He may benefit from a prescription diet and bladder supplements to minimise bladder inflammation.Whether or not there is a medical issue, his behaviour will also be ingrained by now as it's been going on for so long.We need to ensure he always has access to those 3 clean litter trays and I'd consider trying one with a roof and different litter substrates. Many cats have strong preferences.When he does go outside the tray, be sure never to punish him or shout at him as thus creates anxiety and often worsens the behaviour.Any soiled areas must be cleaned right away with an enzymatic cleaner to prevent re soiling. You're right to block off areas like upstairs.Cats who urinate outside of their tray very commonly have to share their territory with other pets. It may be that he's finding it hard to share his home, even if he's always lived with the others. Most cats are natural "lone rangers" and find it stressful to have others about. This can commonly lead to the behaviour he's displaying.Ensure he has all of his own resources and his own place to rest that the others can't go, such as a cat need on top of a cat tree.It may help to use a Feliway Friends plug in too.Icatcare have some excellent advice on the subject:
https://icatcare.org/advice/feline-lower-urinary-tract-disease-flutd/