I don't know if they ever grow out of it. My 9 year old cardigan will still eat litter crunchies if given half a chance. It dehydrates him horribly and he drinks outrageous amounts of water. That's usually how we catch on--although once he walked into the room with some litter stuck to his nose.

I've got hooded litter boxes and turn the opening toward the wall. He's a bulky dog and not overly bad, so this is enough to dissuade him. One of the boxes has a flap door too, which might keep a dog out.

Good luck---it's a nasty habit, but they seem to love it. I've heard it's because cats poo out more protein than is in the average dog food.

Ours do this too - we call it the smorgus board! The poor cats also discover they are getting washed by the dogs - we know there is an ulterior motive

Ewwww! Frin is liking litter cruchies - ewwww!

__________________

Irish Red and White Setters - Nuala, Lottie & Taz
Irish Wolfhound - Ripley
cats - Larkin & Runyon
Degu - Carlisle

RIP Nutmeg, Nimrod & Keats

We have 2 house cats and 5 dogs - the only way we can stop this is by clever use of stair gates. The cats can escape the dogs and also the dogs can't get to their litter tray.
Good luck!