Researchers have claimed that dogs in kennels may show signs of extreme distress often linked to mental illness.

Lead author Hamish Denham of the University of Bristol's Anthrozoology Institute with his team videotaped male German shepherd trained police dogs and noted that the dogs bounced off the walls, Discovery reported.

They also saw that the dog spun - turned in tight circle pivoting about their hind legs, circled walked or trotted around perimeter of pen in circles or paced - walked or trotted back and forth along an imaginary line.

The researchers said that such repetitive, obsessive behavior is associated with numerous mental health problems.

In the dog study, about 93 percent performed some repetitive behavior.

The new study has been published in the journal Physiology and Behavior.