A Thestral is a breed of winged horses with a skeletal body, face with reptilian features, and wide, leathery wings that resemble a bat's. They are very rare, and are considered dangerous by the Ministry of Magic.
A dog collar is a piece of material put around the neck of a dog. A collar may be used for control, identification, fashion, or other purposes. Identification tags and medical information are often placed on dog collars. Collars are also useful for controlling a dog manually, as they provide a handle for grabbing.
A note about collars: Never use a choke collar to tie out a dog. However, if you do all this work and then use a regular buckle collar, your dog may pull out of the collar and disappear anyway. This is why I use a martingale collar. Martingales should not be left on 24/7 or left on an unattended dog.