Infection occurs via the drinking water and from regurgitated food or crop milk.
Most pigeon flyers are familiar with these symptoms, but we must concern ourselves with the subclinical picture. These symptoms are more subtle and may only manifest themselves by slight inflamation of the throat and strings of mucous. Sometimes we see no symptoms at all. Recent studies of racing pigeons have revealed a negative effect on performance in even the mildest of cases. Perhaps more importantly, even a subclinical case of canker in pigeons stressed from shipping and racing can open the door for more serious viral and bacterial respiratory problems.