If you have a sighthound you have a dreadful responsibility where sheep/cats/little dogs are concerned. You just must not trust it off the lead if there is a possibility that they will chase sheep or course cats and small dogs. They will kill them!! That is a fact! I have owned and bred sighthounds for over forty years and, unless they are brought up from puppyhood with livestock/cats/toy dogs they WILL chase them if they run. In fact they will chase strange sheep etc. even if they don't bother with the ones they are used to. PLEASE don't take risks with your dog's or other people's animals lives
On another note do you know that George is not a lurcher but a "long dog". This is the term for a cross between sighthounds.
If you are interested(and my battery lasts) the difference is this.
A sighthound or a long dog when coursing a hare will follow the true line of the hare, i.e. follow it on it's course.
Someone, either by design or accident, discovered that a sighthound crossed with something that had a portion of wit, usually a border collie would have the sense to realise that if it ran across the line and intercepted the hare it would catch it. This is known as "lurching" hence "lurcher". This is excellent if you want to catch a hare or rabbit but a major fault in a coursing dog.
Nowadays, of course, we don't course hares but plastic bags on a lure.