Our rescue lurcher snapped at my eldest daughter tonight. We have had him about 18 months. He snapped at her once before but she approached him when we had a bone so we put it down to resource guarding. He growled at my youngest daughter the other day, but I thought he may have been asleep when she approached him. But tonight, I was watching. He was wide awake and my daughter went up to him to give him a gentle stroke to say goodnight. Out of the blue he growled and very quickly followed up with a snap. The girls are older and very sensible. They adore him and he seemed very close to them. He sought them out this afternoon, to go and sit near them and this is typical behaviour for him. We just don’t know what to do. My youngest was sobbing and terrified. My eldest defended him as she loves him so much, but I saw this with my own eyes. Me and my husband are devastated. He can be reactive on the lead on walks but otherwise is a gentle, loving boy. What are our options? Please help and he kind.