Hunting Dog Collar
Probably England, painstakingly wrought from iron, ca. 17th/18th century, perhaps earlier.
The spikes would have protected the dog from attack by another dog, or large animal like a bear.
Spikes projecting from the "bands" are formed into shape, the spikes at the iron plates peened from behind. Must have been worn by a large dog, as the inner diameter is about 6 1/2 inches (spikes project up to 1.5 inches). All original; rust free.