Premise: The term cur refers to the lowest class of nameless dog or Pariah Dog, generally a mixed-breed dog. Originally the word "cur" referred to a certain English purpose-bred, short-tailed cattle driving dog known only from historical records, the cur dog, but in modern usage it applies to any mixed-breed.
Hypothesis: Originally the word "cur" referred to a certain Scottish purpose-bred, short-tailed cattle driving dog known only from historical records, the cur dog, but in modern usage it applies to any mixed-breed.