In the UK of course. Muslims consider dogs unclean:

Where Muslims object, officers will be obliged to use sniffer dogs only in exceptional cases. Where dogs are used, they will have to wear bootees with rubber soles. “We are trying to ensure that police forces are aware of sensitivities that people can have with the dogs to make sure they are not going against any religious or cultural element within people’s homes. It is being addressed and forces are working towards doing it,” Acpo said.

It’s nice that they are being so thoughtful of the religious sensibilities of their terrorists.
But evidently they are going too far:

Ibrahim Mogra, one of Britain’s leading imams, said the measures were unnecessary: “In Islamic law the dog is not regarded as impure, only its saliva is.

Make sure you read the rest of the article because it’s pretty funny.
(via)