Not always. They put heavy collar around there heads to build up neck muscles. I have been researching this and I am a big activist against dog fighting. On animal planet they show raiding dog fighting places and they find instruments that are used to exercise the dogs. They have tread mills and weight lifting equipment. They quite ofter wear these collar that weight sometime as much as 25-50 lbs. He might be innocent but I have never none an owner wanting to make a strong dog already stronger. I don't mean to make you mad but someone asking that made me very concerned. I feel very strong about this.