A happy ending for you Dunna, my mates dog had similar experience after a short dig he seemed to collapse and take a slight fit for a few minutes ,he was rushed to the vet who kept him in for scan of his heart and put fluids in him. He said the lack of air in the tube plus the adrenaline pumping caused it as one of the valves in his heart was not up to scratch, hes now retired, y/s Jigger.