Having never ever seen this in a large breed before, has anyone else? how long would you leave it before veterinary intervention?

How old is the dog?

Two of my dalmatians had it, but I wouldn't call them a particularly large breed. Presumably it's the canine teeth? If they're not out by 6 months I'd get the vet to remove them.

5and a half months, top canines affected only

Those are the usual ones to be retained. I wouldn't leave them longer than 6 months.

In the toy breeds it happens more frequently, and when I take pups that I keep for the 6 month puppy health check, any remaining puppy teeth are booked for removal.  So it does look like 6 months, whatever the breed, given answers from other members.

My GSD didn't lose his last canine until he was 11 months. The vet had checked him and was going to remove it when he was neutered but it came out of its own accord

> My GSD didn't lose his last canine until he was 11 months

Yes, I know this can happen, but it does depend how the teeth are situated.  I knew someone with a Toy Poodle from top lines, he was stunning.  Owner asked vet to remove an extra canine at 6 months.  Vet said it wasn't necessary.

The dog now has a tooth growing at almost right angles, and it pokes out of his mouth permanently.  Milk teeth can, and do, cause problems.

In a 51/2 or 6 month old pup, I'd be giving him plenty of very large meaty bones to chew.  Often, this sorts out teeth that are reluctant to come out ;)   If that didn't work, then I'd be thinking of the vet ;)

11 months for my crestie and gave him bones and a knotted ragger that i got him to tug around with the big dogs and it came out sometime between 11 months and 12 months old

I have seen this few times in my breed.
Silly question but have you tried taking a hold of the tooth and tugging straight down?
We have found many teeth that feel like they are not moving much just pop out when you do this :)
Never needed a vet so far just bones and the gentle tug has worked many times too :)
It needs to be straight up or down depending if it is bottom of top one...

Having seen the teeth that the vet removed from mine there was no way they were going to fall naturally - the roots hadn't been re-absorbed at all (as usually happens), and were over an inch long!

I was thinking of starting a post on this very subject! My 5 month puppy still has her baby canines as well as the adult ones. Her mother did the same thing and they came out naturally. I've been gently wiggling them each day and encouraging tuggy play, and they are perhaps a tiny bit looser than they were 2 weeks ago. Will it count against her in the ring, ie shall I get them removed if they don't come out naturally at just short of 6 months? Or will the judge not notice them when checking the bite?

The judge will certainly notice them, but whether she's penalised her for it is up to him. The problem with leaving them is that they can make the adult teeth be in the wrong position, which can cause other, more difficult, problems.

I certainly wouldn't leave them much past 6 months, it just that her first show is 28th December, so it's a question of getting them done just before Christmas if I need to.... Presume it's just a question of leaving them for a morning or whatever like when you get a dental, not a major op to need recovery time. :-)

Be careful with bones and tugging. You may get the tooth out and leave the root and its the root that causes the problem. If it hasnt disintegrated by 6 months its best to get a vet to  remove the tooth. I had a few retained teeth in a litter last year........never had it before.

I think I'd be too scared to tug, I just wiggle. Come to think of it, that must have been what happened with her mother as a puppy - like I said, she had retained puppy canines, and I wiggled them as advised, and one evening the tooth had vanished and just a little red lumpy bit was hanging down. I was petrified in case I'd somehow made the tooth come away and leave the pulp and nerves and everything exposed, but she wasn't acting odd at all so I left it overnight, and in the morning it was all gone.

suddenly one has gone and 2nd one is wobbling....panic over :) thanks for helpful advise.

Lucky you! Hetty's are still nice and firm.....