5 yr elderly lab have muscle spasms surrounded by stern when self pet.?

When I pet my 5 year old chocolate lab's put money on, his back tightens up contained by muscle spasms. He has never have this before. He stands nearby and lets me rub his back- it doesnt give the impression of being painful for him, but this sort of spasm scare me. He tries to reach his put a bet on and itch at it. There are no bumps or anything that looks wrongg...any advice to what it may be?
Answers: nil but a bunch of nerves close to skin--all dogs do it more so when they get around 6--want a giggle take a stiff brush and stroke it down backbone lol as far as i can see they love it

Related Questions and Answers ...