Why are tails commonly docked?
Historically, and I mean a really long time ago, dog tails were docked to protect against injuries during hunting. At the same time, an English law was passed which taxed “non-working” dogs. Rat Terriers are natural hunters, and were (and still are in some cases) commonly used for hunting, thus their tails were historically very commonly docked. A natural tail is not a penalty in the breed standards. The term “NBT” (natural bob-tail) refers to dogs that are born with a bob tail already, and so do not need their tails docked.