Spiked dog collars were invented many years ago as a means to protect the dog wearing the spiked collar.
The spiked collar was worn by the dog to protect the dog should it get into a fight with some other predator such as Wolves.
The spiked dog collar was invented and first put into use in the Middle ages when dogs were primarily used as hunting dogs.
Another term for a spiked dog collar is a Wolf Collar because it was used to protect the dog from Wolves.