Thanks for the tips @TW - as part of her regular booster stuff she sees the vet then - we mentioned it before and they did not seem that concerned - perhaps we'll book her in again !
You can gauge if she is actually dehydrated by the elasticity of her skin - if you pinch up the skin on the top of her head, if it take a little long to subside, she may be dehydrated.
(I am not a vet. My advice is no substitute for a vet's advice.)
You have seen a vet haven't you @anthonyj?