Simply, off-lead training means the search dog is unleashed and responds to verbal signals and commands from its handler. On-lead training means the search dog is leashed to its handler. The handler should decide early in the dog's training which method to use.

Without the handler the dog can often go into small or brushy areas that the handler can't, and there's no leash to get tangled or caught in debris. Off-lead SAR may also shorten the time it takes to find the victim because the dog can cover ground faster than its handler.

An off-lead dog must be trained to give a much stronger alert than an on-lead dog. Training time is usually longer because the dog must be trained to take directional controls and must be able to take them from a distance. Also, the handler cannot watch the dog as closely or respond as quickly if the dog is endangered. This is especially important because an off-lead dog may go places the handler has determined unsafe, thereby putting the dog at greater risk.

With on-lead training the handler has more control, training time is typically shorter, and the alert signal can be something more natural for the dog. On-lead training also allows the owner to better protect the dog, and it may allow some dogs that might not be able to do SAR work to perform certain aspects of it.

The leash can get caught in debris, and it is often harder on the handler because he must cover the same ground as the dog. Because the handler can't cover as much territory as quickly as the dog, this type of training may slightly increase the time it takes to find the victim.

Yes. Some dogs can be trained to do either. These dogs are usually trained first to work on lead, then moved off lead.

There are a few, but not many, units that will not allow a dog to go on missions on lead. This should not be a major factor in the handler's decision, however, because most dogs can eventually be trained to perform off-lead work.