Will Falconer, DVM Moderator
This is remarkable, but I doubt if it's maternal antibodies. Those are short lived, by definition, and usually gone by 16 weeks. No, I think a 6 year old must have had exposure somehow, most likely to recently vaccinated dogs. Shedding isn't supposed to happen with this vaccine, especially if it's killed, but maybe some other form was used that got the transfer to this dog. Very peculiar.