Birds with respiratory infections usually look tired or will stay off to themselves. Look for any sneezing, wheezing, rattly breathing, or nasal drainage. Do they have a bad odor? MG can typically cause the swelling and runny eye from sinus infection. Coryza does the same, may smell bad, and nasal drainage will be thicker, and symptoms worse. Separate and medicate the sick birds. Some people cull sick birds to control the spread, but at least close your flock to birds going out or coming into the flock. MG can be common in backyard flocks. Your state vet or poultry lab can help with testing, or if you cull or lose a bird, they can do a necropsy (autopsy) to test for what disease.
Last edited: