Crup

A Crup is a wizard-bred dog  that strongly resembles a Jack Russell Terrier, except that a Crup has a forked tail. They are wizard-bred dogs, since they are extremely loyal to wizards and ferocious toward Muggles. They will eat almost anything.

Crup owners are required by law to remove the tail of the animal when it is six to eight weeks old, using a painless Severing Charm in case they are noticed by Muggles. A license from the Department for the Regulation and Control of Magical Creatures must also be obtained, and the owner must pass a test to see if they are able to control the animal in Muggle-inhabited areas