My lab has always had Advocate but the last time I gave it to him he seemed to have a terrible reaction to it. He cried for two days and was so out of sorts. Vet has suggested trying again in case it was a one off but I'm really not keen - he's an old man of 12 now, deaf and has arthritis and I really don't want to stress him out. He has drontal too, which he never has any issues with. Any suggestions please?