Turkish Spike Collars are also called 'Wolf Collars'. They are designed to protect dogs from wolves, fitted with elongated spikes to stop predators from directly attacking dogs on the neck.

In most parts of the world, these collars are no longer being used, however, they can be still found in Spain and Turkey. The metal spiked collar in the pictures are samples of the traditional collars worn by Turkish Shepherd dogs while guarding their herds. Flocks of sheep and goats are prey to fierce animals as they graze in the mountains and valleys of Turkey. These collars serve to protect the dog and become an aid in fighting against wolves and bears. The styles of collars vary from village to village, and from one blacksmith to antother. 

"A wolf collar is normally made out of metals such as iron. The length of the spikes can be quite long, but styles differ in different places. (...) The spikes provide protection and can also be used as a weapon. There are some tales that suggest that dogs were only given them after they had killed their first wolf; however, these are normally considered to be inaccurate. The use of wolf collars is now banned in some countries, as it is seen as cruel to dogs." (Wikipedia)

==========================================================================================================================================

In "The Story of Turkey" (2002) Elizabeth Rassiga describes her observations during her travels in Anatolia:  "We shared the space with the last nomad Shepard to leave the high country pastures for the season.  Three sheepdogs, a flock of 500 fluffy-coated sheep and a few goats accompanied him. (...) The true guardians, however, were the ferocious sheep dogs, who lazed along the perimeter.  Of the three dogs, two were support dogs; the large, sandy-colored lead dog, wore a two-inch steel collar with four-inch metal spikes around his neck to protect him from the gray mountain wolves that prey upon the sheep. (...) That night, I was awakened by the sound of the approaching bells.  The sheep, who had spent the day trying to stay cool, were now busy grazing.  The ringing grew louder, and I realized that the entire flock was headed for my tent.  I’d enjoyed watching them across the narrow valley all day, now they’d come to visit.  After a while, my tent became totally engulfed by the sheep. (...) Ismet had tutored me on the behavior of sheep dogs.  Anything that approaches the flock, from outside, is in peril.  I, however, was now at the center of the flock and the dogs would protect me as well."

===========================================================================================================================================

Below are pictures of modern Turkish collars, most of them quite unique,  colorful, designed with beads, bells, and other decorative trinkets:

The Nazar Boncuk charm (or Evil Eye Bead) is a big blue glass "eye” that is commonly used in making of these fancy dog collars. The eye stares back at the world to ward off the evil spirits and keep a person safe from harm. It is one of the most common items of decoration in any Turkish home. It is found hanging over doors, in cars, and from peoples' necks. Some Turks carry a few beads in their pocket and give them out to guests and visitors. No wonder, that the Evil Eye Beads are found on the leather collars made for the Livstock Guardians in the area.

==========================================================================================================================================

Iron collar pictures from Midle age/Reinnasence; Gaston Phoebus, Count of Foix , 1389 “Livre de Chasse” (The Book of Hunting)

Collar of Bering (circa 1.515 )

Another illustration coming oput from a wood engraving (circa 1480)

Picture source:  Manuel Turanzas