anaphylactic shock can be bought on my annual boosters, which one of my bitches was unfortunate to have suffered from many years ago, or indeed stings, as it is the reaction to a foreign body in the system. Usually treated - by a vet as an emergency as if left can severely affect the internal organs such as the liver etc - with epinephrine, and I would have thought an epipen more appropriate as a stand by, cant see what piriton would do with such a severe reaction, but maybe I am wrong?