Zazzy is attacked

It has been really hot this week, I thought I would take the girls down to the river near Chertsey Bridge where they could have a paddle and swim. We had just got out the van and they were running through the long grass, when out of nowhere a large tan and white greyhound/lurcher appeared, chasing them down. I only had time to call once, as they came back to me the lurcher chased down and pounced on Zazzy, knocked her to the ground and held her down as it stood over her tearing chunks of fur out of her as she screamed. Luckily she was close and I was over there in a heartbeat, lifted it up and backwards by grabbing under its hips, taking its hind legs off the ground, I threw it away from Zazzy. Thank goodness for all involved it reconsidered going back in, as I was now in its way and left it no doubt it would have to go through me first; it turned and ran off. No owner in sight. Poor Zazzy was whimpering and crying and staggering to her feet.