BOCA RATON, Fla. -- A dog trainer said that a dog was so ill behaved that she needed to "exorcise" the rebellion out of the puppy -- but the dog's owner said the trainer's methods led to the German shepherd's death.

Lisa Berstien said that she took her dog, Ringo, to trainer Jill Deringer after Petco referred her to the trainer. Deringer is employed by Petco.

Berstien said that Deringer came to her home Sunday to perform a procedure on Ringo. Berstien said that Deringer muzzled the dog and sat on him. She said that Deringer had her hold her dog's paws still while the trainer poked the dog in the head and stomach for about an hour.

Berstien said the dog began foaming at the mouth and lapsed into unconsciousness. She rushed the dog to an animal hospital where it later died.

The Palm Beach County Animal Control Division is investigating to see if any criminal offenses were committed.

Petco said that it is investigating the incident, and has contacted its lawyers. Representatives said that they are not responsible for what their employees do on their own time.

Deringer said that the dog's death is a tragedy, but that Ringo tried to attack her and if he hadn't been muzzled, she would have been mauled. She also attributed the dog's condition to having been chained too much and not getting enough exercise.