Jealousy and Sharing

[Linda,Yankee & Finn]

Hi everyone,

Yankee is a wonderful friendly dog but lately he has become possessive. If he sees another dog with a ball or stick, he goes to play with them until he gets what they have. If they try to take it back, he snaps. He has always shared his water bottle but the last couple of times that another dog came to drink with him, he snapped.

He is also jealous if his best buddy (Charley) starts playing with another dog. He tries to get Charley away from the dog by poking him with his nose or trying to wrestle with him. If that doesn't work, he barks at him. Now if he thinks another dog is coming to play with Charley, he will snap at them hoping they will go away. He seems to think that Charley is his dog and only his. Charley on the other hand, will play with a variety of dogs.

How should I deal with this behaviour? I have been scolding him when he snaps for any reason. Should I force him to share his stuff? How do I get him to let another dog join in their play or get him to play with other dogs when Charley is around?

[Linda,Yankee & Finn]

I do bring Yankee to the park without Charley 3 or 4 times a week. He also knows drop it and does this quite well at home. It's different at the dog park. The dogs there chase each other for sticks including Yankee. If he gets it, he will put it down and won't let anyone take it.
He is really attached to Charley. I have to leash him when Charley isn't meeting us because he will run into the parking lot to look for him. I can't take the leash off until we are far enough into the park.
i