What are the common causes of eye lesions in chickens?
Zhao Deyue from Sihe Township, Sihong County called to report that one month ago he bought a batch of 2000 chicks, which are now 35 days old. At 25 days of age, some chicks showed tearing in both eyes; later the eyelids became swollen, and some chickens went blind in one eye or completely blind in both eyes. Currently about 50 chickens are affected each day, with a total of 300 affected. Sick chickens huddle with necks drawn in, stand listlessly, eat little, gradually lose weight, and scratch their eyes with their claws; when about to go blind, there is a milky white pus-like substance in the eyes. Treatment with cephalosporin drugs, roxithromycin, gentamicin and other drugs was ineffective, and there was no improvement after vaccination against fowl pox, but so far no chickens have died. He sent the sick chickens to the Sihong County Animal Husbandry and Veterinary Station for examination, but due to limited conditions, pathogen isolation and identification could not be carried out, and no diagnosis was confirmed. His neighbor Zhao Deguang's chickens also showed the same symptoms. He asks what disease the chickens have and how to treat it.
Chicken eye disease is not an independent disease, but a local symptom and reaction of some disease. There are many kinds of diseases that cause eye disorders in chickens, and it is difficult to confirm from the symptoms alone which disease is causing them; diagnosis requires pathogen identification.
The common diseases that cause eye lesions in chickens include: (1) Ocular Marek's disease. Also known as gray eye disease. Main symptoms: the iris pigment disappears and turns grayish white or blue-gray (normally chestnut or orange-yellow); the pupil shrinks, the edge is irregular and serrated, and in severe cases the pupil disappears, eventually leading to blindness. (2) Encephalomyelitis. Main symptoms: in the later stage, the surface of the eyeball is covered with a grayish white membrane, resembling cataract, and both eyes go blind; it occurs mostly in chicks. (3) Vitamin A deficiency. Main symptoms: exudate in the eye socket is milky or like bean curd residue, the cornea is cloudy, and there is more eye discharge in both eyes. (4) Ocular fowl pox. Main symptoms: eye abscess, from which clumps of caseous material can be squeezed out, mostly unilateral, with a chronic course. (5) Aspergillus eye inflammation. Main symptoms: caseous small spheres form under the nictitating membrane, the eyelids bulge, and there is ulceration in the center of the cornea. (6) Mycoplasma disease. Main symptoms: tearing in the early stage, then eyelid swelling and red conjunctiva, the exudate changes from viscous to purulent, the upper and lower eyelids stick together, the eyeball protrudes, and the eyelids swell. (7) Infectious rhinitis. Main symptoms: it spreads from the upper respiratory tract to the eyes, with marked swelling of the head, eye abscess, and gradually increasing secretion that changes from serous to purulent and pale yellow. The eyelids stick together and become edematous, and finally the eyeball becomes inflamed and blindness occurs. It is mostly unilateral. (8) Infectious laryngotracheitis and infectious bronchitis. Main symptoms: eye swelling and photophobia, closed eyes, tearing, red eyes, and conjunctivitis. Infectious laryngotracheitis is mostly bilateral, while infectious bronchitis mostly has symptoms in one eye. (9) Ocular colibacillosis. Main symptoms: unilateral eye inflammation, eyelid swelling, tearing, and viscous secretion.
From the situation reported by Zhao Deyue, the disease in their chickens may be one of ocular colibacillosis, mycoplasma disease, infectious laryngotracheitis, or infectious bronchitis, but confirmation requires pathogen isolation and identification. If a diagnosis cannot be made for the time being, symptomatic treatment can be used to relieve symptoms. For example, rinse the eyes of sick chickens with 3% boric acid solution once a day; apply anti-inflammatory drugs externally, such as chlortetracycline eye ointment. Eye disease in chickens generally has a chronic course, and during treatment cod liver oil should be supplemented, in addition to antibiotic treatment.