'The Boy Who Cried Wolf' updated by automatic sheep collars

Wired reports that Swiss scientists are trying to develop a sheep collar that will notify shepherds when wolves attack their sheep, and will release a chemical deterrent.

Well and good, but this leaves several questions unanswered. The collar registers the increased heart rate of the sheep when they are scared by wolves. I thought that sheep were unable to tell the difference between wolves and large dogs. What is to keep the collars from registering the sheep's fears of dogs? But sometimes dogs do attack sheep. Will the colllars work in these cases?

But if the collar is successful, what will the hungry wolves eat?

It sounds as though the tests have been hard on the sheep.