at least, there is one missing from a pack he found and ravaged in the last half hour. One of the others has tooth marks on it 
Scary.
dh has taken him to the vet, who is going to give him an injection to make him vomit and watch him for an hour or two. Some (US) stuff online says not to make them sick in case corrosive alkaline stuff burns their gastro tract - but knowing Mouse, he would have swallowed it whole anyway.
I feel guilty, but otoh the chicken soup was left alone, ditto a pack of chocolate biscuits, and he hadn't jumped up or chewed anything for ages - so this is really bad luck. It never occured to me to hide brand new pack of Duracell batteries that were up on a higher surface 
Crossed paws or happy ending battery-eating stories if you have them, please...