As a person who likes to walk, I don't like the invisible fences. A few months ago while walking on Odessa Circle in Tamarind Grove, there stood the largest dog I've ever seen, a Great Dane. I turned and walked the other way, I didn't want any part of that dog. I love dogs, but I was bit by a German Shepherd when I was about six and had to get rabies shots, so I've always been leery of big dogs.
One of the fellows on my softball team lives on Odessa Circle, so I asked him about the dog. He said, don't worry, they have invisible fencing. I still don't like it when the dog is out there. He looks just like this photo but is black & white in color.
As the previous poster mentioned. The fence doesn't keep out other creatures, and gators can easily enter a yard and snatch a dog. I grew up in Florida and that happens all the time. There was a national news story last year about a man in TV who had go in the water and wrestle with a gator to get his dog back. See the link below;
Man fights off alligator to save dog - YouTube
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