Sometimes we might encounter a pet with an especially high tolerance for pain, high pray drive or ball drive and even dogs with aggression issues. This unique situation require the type of system that Pet Stop is known for 100% containment. To date we do not have any dogs not contained and we’ve never met a particular breed we couldn’t train effectively. Adam, Mike and the staff at Whispering Oaks Kennels are certified experts in handling all dog situations through CPT and the AKC. Additionally if it is a stronger collar that is needed, Only Pet Stop Brand offers collars that host 6 volt. 7.5 volt and even 12 volt batteries. If anyone can keep them in, we can!