Canker - Trichomoniasis Canker
Cause - This is the most common pigeon disease. It's caused by a microscopic protozoan which is flagellated and, therefore, mobile. It can be transmitted from one bird to another usually through the drinking water, and parent birds can infect their young through feeding.
Symptoms - Infected birds show a definite reduction in activity, ruffled feathers, loss of weight, increased water intake, and diarrhea. Cheesy yellowish deposits can often be observed in the mouth or throat. In advanced stages, a stringy mucous and putrid odor can be detected in the mouth. Young birds are most susceptible.
Prevention - Control stress with half dosage of Improver and AntiFungal, this will control the stress to 0 in the birds.
Maintain regular feed and withering schedules, sanitize drinkers regularly, isolate and observe any newly acquired birds for several weeks, and administer an anti-canker drug http://www.pigeonmad.com/pigeon_medication.php#CANKER or Improver on a regular basis throughout the year. Veterinary recommendations vary from once every three months to once a month. This will depend upon incidence and susceptibility in your own flock.