Beavers in Caithness?

Can any one tell me if there are beavers in Caithness as I think I saw one.

There shouldn't be - they were reintroduced to Scotland in Argyll in 2009 on a strictly controlled trial basis, there should be a decision late next year on whether they'll be allowed out of the trial area.

Could it have been a water vole?

Dog otter by any chance?

Thanks for the replies but it was the size of my small collie dog,dark coated with a tail like a round large paddle, the tail was even darker. It was on the sand and ran into the sand bank on the sea shore. A vole is not that big as for dog otter the tail was different.

Beavers live in fresh water and eat deciduous trees, so unless they were near by, I don't see how it could be a beaver.