
Hi Phillippa!
It's fairly common in gundogs, though I haven't heard of it in any other breed, so this is a new one. Many vets have never heard of it; my Chris wrote an article in the Vet Record some time back, and I think it was quite an education for some of them.
It's called many names, mostly 'frozen' or 'limber' tail. Usually comes on after a cold swim, but can occur when another dog treads on the tail or something similar, so we reckon it is along the lines of a trapped nerve; maybe the tail equivalent of a whiplash injury.
No treatment is necessary as the condition usually goes right all by itself in about 3 days, but occasionally it can take longer. I know some vets have given steroid injections but I think they are of dubious effectivity (is that a word?).
Once the dog has had the condition, it does seem to be more prone to recur, which is bad luck if you're showing, and bad luck for the dog, as it can be quite painful.
Jo and the Casblaidd Flatcoats