My dog is eleven, he weights 13lbs and has been diagnosed with MCTs Grade 3. The Vet prescribed Previcox 57mg, Prednisone 5mg and Benedryl 12.5mg . Last night after giving him the Previcox and Benedryl he started breathing so heavily it was awful. I read online that Previcox and Prednisone should not be taken together. I haven't given him any medication this morning and his breathing is normal and he seems more alert.