They were obviously used in Portugal, the case above in US and someone cited a case in Scotland.
Why S.Yorks?
Think - number of deployments * experience of handler * capability of dog.
Number of deployments. The number of times a cadaver dog is of benefit. The dogs do not cover vast swathes of territory, hoping to perchance upon a cadaver. Police intelligence leads to a relatively small area to search.
Experience of handler. The officer is taken off other duties to become a full time handler. That is a costly resource.
Capability of dog. The vast majority of police dogs are not cadaver dogs. For example, tracker dogs are much more common, because they are needed much more frequently.
Most forces borrow 'specialist' dogs from any force which has them, rather than train their own.
From memory, didn't Tito and Muzzy belong to S Wales Police? Those were the dogs deployed in Luz in June 2014. I have reason to suspect one of those was deployed in Dec 2014 in a car search.