Excerpt from dailymail.co.uk, November 4, 2011:
…But not being free to play off the lead makes them [dogs] more frustrated.
Dogs off one sniffed one another more often than dogs on a lead. They also threatened each other twice as often when on a lead.
‘This is most likely a reflection of the frustration dogs feel when the leash prohibits them from expressing normal greeting behaviours,’ said Inga Fricke, director of the Humane Society of the United States,
She said this is known as ‘leash frustration’ or ‘leash aggression.’
Lisa Peterson, spokesperson for the American Kennel Club, said dogs do not like being stopped from running and playing.
‘They can’t do this run-around behaviour when on a leash and they likely feel more threatened,’ she said.
‘They are also more inclined to resource guard, with the owner being the resource. It’s as though they are communicating.
‘He is my owner. I don’t want you to have him because he feeds and cares for me.