Georgian era (looks like newly brass plated over white metal). I have seen one exactly like this sell at auction for $1300 in 2004. It was described as a Slave Collar despite clearly having 'whose dog are you' engraved upon the name plate. Would look beautiful as a piece of jewellery. The man I bought it from adorned his Saluki with it.
Georgian Brass Plated Dog Chain Collar and Key
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