SportDog makes a lot of equipment for people training bird dogs
. They have one dog fence in their lineup, the SportDog SDF-100. It is the longest range dog fence available, doing 100 acres and is strong. The downside is that the collar is not rechargeable, and the whole system is pretty bulky and not at all pretty.
If you aren't familiar with radio dog fences, you may have heard them called by another name. Radio fences are known by many brand names, and can be either professionally installed, or bought in a do-it-yourself kit. Radio fences also come in two main styles; one that uses a buried wire running around the perimeter of your yard that emits a radio signal, and another that emits a radio signal from a central point.
Where this dog fence collar stands out is that it is super tough. It can take a beating and has really good waterproofing. We had a customer a couple of years ago that left the collar outside and found it six months later when they hit it with a lawnmower. They switched out the battery and it worked perfectly.
What about small dogs on the containment system? I like to take the same approach with the smaller dogs. After 15 years installing invisible underground dog fences I have herd some horror stories. The first thing that concerns me when laying out the containment wire is the dogs safety. Wooded areas can be extremely dangerous for small dogs because of coyote's, if you small dog is in back near the woods it is easy pray for the coyote's. If you pinch the sides the dog can have access to the front yard during the night and the back yard during the day.
One other nice thing about the SportDog Dog Fence is that it comes standard with 1,000 feet of boundary wire. Twice as much as the standard system. Overall a good tough system that is the one to get if you need to go over over 25 acres.