I've just come across this thread and offer a couple of photos of modern passive weapon dog collars from Turkey.
The first example (just like the medieval Hungarian example from ALEX) is from a village blacksmith in Elmali, in the mountains of South West Turkey in 2008.
The second photo is of a collar bought from a blacksmith in the wonderful bazaar in Urfa, just north of the Syrian border in South East Turkey in 2013.
Both blacksmiths said the collars were for use by dogs that protected herds of goats or sheep from wolf attacks.
Having recently dropped the second example onto my wrist from a very small height I can painfully confirm its capacity to do damage!