Just to echo what everyone else has said Joan, fantastic image, perfect timing catching the dogs in full flight. Lots of negative space for them to run into, looks like they needed it for how fast they are going.
Thanks everyone. The dogs are not particularly sharp if you zoom in but I had just whipped round from taking them full on and didn't have enough time to steady myself completely! This was them a second before. They really can move - and this is them after a very long winter layoff so not up to their normal speed!