Wolf collars, which were first used by ancient Greeks, are a type of dog collar with metal spikes designed to protect a livestock dog from wolf attacks.
A wolf collar (also known as Italian: roccale or vreccale, Spanish: carlancas) is a type of dog collar designed to protect livestock guardian dogs from attack by wolves. Wolf collars are fitted with elongated spikes to stop wolves from attacking dogs on the neck. Ancient Greeks used such collars to protect their dogs from wolf attacks. A wolf collar is normally made out of metals such as iron. 
