Sometimes Agressive Jack Russell Terrier

[Streetersn]

We have a almost 4 year old male jack russell terrier who is playful, lovable, excitable most of the time. However, once in a while he has unprovocted biting attacks and we are now at our wits end. We have tried medication, obedience training, and even a behavioral specialist. He is naturally a little agressive, especially with food, possessions, or when we are leaving and have to put a gate up, he has bitten fingers before to cause bleeding, but those we can work around those because we can recognize the signs.
This last weekend at the cottage, where he gets to run around and play all day with two other JRT's, he was lying on the sofa relaxing in the evening. When I came up to him he bit me on the forearm with no warning. The next day, the same situation, and my wife came close to him to pet him on the head and he bit her on the nose which caused quite a bit of damage (three puncture wounds, blood, swelling). This has never happened to this degree.
We have called Ontario Russell Rescue and the local Vet and both say Euthanasia is the only option. We want to explore all possible options first, does any one have any other ideas for places that might take him???

Thanks for your time,

Simon & Nicole and Archie