Barb, My vet said that the lab that he sends the samples to is Antec. I don't know if the spelling is correct. He says that this lab is used by most vets, so it shouldn't be difficult to get a number or address. They should cost about $40. My little girl, Zinc, had her titer a year after her last shot (accompanied by an anaphylactic reaction). The results indicated that she was still protected from distemper. I still worry though. My vet says that yearly titers should be sufficient. Has anyone else here heard otherwise? Do keep in mind that the titer will give you a ballpark figure, and nothing is a sure thing. Suzanna [Posted in FML issue 3409]