My 8 month old xbreed pup used to shake when she had been on a decent walk.
She would come home curl into a ball and shake for a while or untill asleep.
She has now started doing this whether or not she has been for a walk.

The shakes are nor continuos they seem to be in line with breathing ....

Has anybody else experienced this problem? does anybody think it is a problem?

Some dogs breath rapidly when over excited - is the shaking related to a breathing pattern? Dogs usually have 10-30 breaths per minute - if the dogs breathing isn't normal it may have a health problem.
Another option could be that the dog is 'fitting' , what other symptons do they have during these periods?

Nikki

Hi,
The shake is more liek a shiver when she is either breathing in or out.
She is usually curled in a tight ball and very subdued when this is happening.
She has started doing this every morning now and some mornings doesn't eat her breakfast.

I think you should have her checked out by the vet if you haven't already, hope its nothing too serious.

does it look like she is shivering?

Yes, It looks like she is shivering........it used to be after excercise but now it's more often especially firts thing on a morning.