Why does your staffy chase his tail?

There could be a few issues cause this behavior. The main one could be boredom. If a dog is not exercised properly and not given proper ways to expel the energy it will eventually be channeled into bad energy. This could lead to everything from obsessive behaviors such as chasing the tail, destroying things, aggression, and other types or unwanted behaviors. You might to give the dog longer walks and more playtime. If you have a insane schedule like me you might want to look into getting a dog walker or sending the dog to doggie daycare. Where he will not only socialize but also ware his self out. Also if you have the time you might want to look into a agility or rally or a type of activity like these. These activity are really enjoyed by dogs with lost of energy. When you have to leave the dog try giving him something to do while your gone. This could be anything from a Kong stuffed with treats or cheese whiz or peanut butter, to hiding pieces of treats or kibble around the area (if left in a fenced yard) . The dog will occupy his time tying to find all the kibble instead of chasing his tail.