These herd dogs look metal but its out of practical reasons. Anti-wolf collars are made out of metal spikes and put around dogs neck as this is the area wolfs attack. They will hurt themselves on the spikes and let the dog escape their grip.

They were used for hundreds of years and medieval armies even had them as standard gear for their war dogs. In reality, the collars were never very effective against wolves as a pack will easily find a way around it, hence this is now quite rare to see