lull v> ”01 Penn State Poultry j Pointers EYE DISORDERS OF DOMESTIC POULTRY Patty Dunn, DVM Animal Diagnostic Laboratory Dept. Of Veterinary Science Flock owners, service people, and other poultry health profes sionals often overlook the visual health of birds in their care because eye disorders are generally not a widespread problem in most chicken and turkey flocks. However, because all birds rely heavily on their sense of sight to carry on their daily activities, increased incidence of ocular abnormalities in a flock can result in a significant flock performance problem. A visually impaired bird is at a major disadvantage in competing for feed, water, and social position in a population of birds in cages, on die floor, or on range. When birds with impaired sight are moved to a new housing situation, many will die because of dehydra tion and starvation. To follow are some of the com mon disorders, diseases, and dis ease agents affecting the eye and associated structures that impact negatively on bird health and flock performance. Ammonia Toxicity Ammonia gas (NH 3 ) is the most common eye irritant that domestic birds encounter. Ammonia gas is inevitably produced in the poultry house when the nitrogenous waste product of birds, uric acid, com bines with water in the environment. POURED SOLID CONCRETE •"V-. • -* .£• *■ Far Lafl: 1-Million Gallon Circular Manure Storage Tank Far Right: 2 Sllaga Pita livßam Manure Receiving Pit ■} / - -. ’* flT'*' - ’ ~ 1 1,1 300’ Long Manure PH For Hog Confinement Invest in Quality • It will lest a lifetime. All sizes availsble - round or rectangular High NH3 levels are commonly due to poor management of venti lation. The goal of proper ventila tion is to limit available water in the environment and vent any nox ious gas away from the birds. The ventilation system must control water (moisture) in order to control ammonia. Ammonia gas is extremely irri tating to the membranes that line the eyelids, eye, sinuses, and tra chea. Ammonia dissolves in the liquid on mucous membranes and eyes to produce ammonium hydro xide. Ibis compound is an irritat ing alkali that causes inflammation of the delicate membrane that lines the eyelid and covers part of the eyeball known as the conjunctiva. Conjunctivitis, with characteris tic reddening and swelling of the eyelids, results. Affected birds appear photophobic and painful around die eyes. If high ammonia levels (above 100 ppm) persist, the covering of the cornea, the outer most part of the front of the eye ball, can become disrupted or ulcerated and blindness can occur. Marek’s disease, a neoplastic viral disease of chickens, is best recognized as causing leg weak ness, paralysis, or tumor formation and death. However, there appears to be an increased incidence of a form of Marek’s disease that first manifests itself as blindness. In this situation. IS- to 20-week old pullets are commonly noticed to be visually impaired. Some times irregularities of the normally sharp and regular border between the iris and pupil can be seen. A gray discoloration of the colored portion of the eye may be present. Often no grossly visible eye abnor- Since 1972 ... The Original And The Largest STORAGE SYSTEM SPECIALISTS Take the questions out of your now construction. Call Balmer Bros, for quality engineered walls. CONCRETE WORK, INC. ,/,F Marek’s Disease . Manure Storage For Hog Confinement 82' Boom Placing Concrete malities are present. Proper diagnosis of ocular Marek’s disease requires micro scopic examination of tissues by a veterinary pathologist. There will be characteristic infiltration of neoplastic and inflammatory cells into various structures of the eye, including the retina. A recent study 'has shown that conventional Marek’s disease vac cines may not adequately protect chickens form the particular virus that causes this form of disease. Bacterial Infections Systemic bacterial disease in youAg chicks and poults can lead to bacterial invasion of the eye with inflammation damaging all structures within the eye itself. Salmonella bacteria, particularly Salmonella Typhimurium and Sal monella Arizona are known to cause severe opthalmitis and blindness. Often these young birds acquire the infection from the hen or through a navel/yolk sac infection. Fungal Infections Aspergillus mold, although usu ally thought of as a respiratory tract pathogen, can invade the brain as well as all structures of the eye. A yellow caseous plaque may be seen under the eyelid or within the eye. The presence of the mold invokes an intense inflammatory response, and damage to the eye can be severe. Pox Avian pox, a disease of many types of birds caused by various pox viruses, often affects the skin of the head and face where it causes raised nodules and scabs. If these lesions are around the eyes and (Mi the eyelids, resulting swell ing can impair eyesight Turkeys and Bobwhite quail in particular can be severely affected. The eye itself remains unaffected, and once the lesions have resolved, eyesight should be normal. Respiratory Disease Upper respiratory pathogens (viral, bacterial, and protozoal) often cause conjunctivitis that should resolve when the disease runs its course. Examples are laryngotracheitis virus, Newcastle “ \ >-«' *• -• r-,f '■ 1&M.... ■' «*» »#>:- - ; * IV '^W \’jm —* Houm Foundation Wall Concrata Pit Sat-Up For Slatted Floors disease virus, infectious bronchitis virus, Bordetella, Haemophilus, Chlamydia, Mycoplasma, and Cryptosporidium. These pathogens do not damage the eye itself, but may cause dis comfort leading to rubbing and scratching of the eyelids, but rarely result in permanent eye injury. Many of these disease agents can also produce a sinusitis, caus ing the sinus directly under the lower eyelid to swell gready. New castle disease vims can cause a transient conjunctivitis in people, so care should be taken when handling and applying live New castle disease vaccines. Avian encephalomyelitis (AE) virus, which primarily affects the central nervous system, can cause cataracts and general eye enlargement The lens becomes fragmented and can no longer function effi ciently in focusing images. Vacci nation of breeder replacements for AE is highly effective in prevent ing the condition. Other infectious agents that infect the brain can impair vision at the processing level, while the eye itself, as an image receptor and transmitter, remains functional. Certain vitamin deficiencies, notably vitamin A and vitamin E, can be involved in visual impairment. These deficiencies are extreme ly rare in poultry on commercial feeds. Vitamin A is necessary for the production of visual pigment of the retina as well as for die mainte nance of the lining of the tear ducts. Vitamin E. passed from the breeder hen to the fertile egg, is necessary for maintenance of the lens protein in the developing embryo. Congenital abnormalities in the formation and placement of the eye and eye socket should be of low incidence in commercial poultry. 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PETERSHEIM 117 Christiana Pika, Christiana, PA 17509 Answering Service 215-593-2242 Chicks or poults with one or both eyes missing or eyes of reduced size or forward displace ment of eyes may be seen. The cause may be hereditary or may be due to improper incubation or pre incubation conditions. Affected chicks are usually noticed at the hatchery during chick processing and culled. Exposure of growing poultry to certain types of continuous artifi cial lighting has resulted in eyeball enlargement (“bug eyes,” “pop eyes”) with accompanying degenerative changes and blindness. Cataracts Most cataracts in birds are spor adic in occurrence and are of unknown causes. Flock problems involving catar act formation have been linked to vitamin E deficiency, avian ence phalomyelitis infection, and conti nuous artificial light. Eye-Notch Syndrome Eye-notch syndrome is a condi tion in caged layers characterized by lesions of the lower eyelids. Lesions range from small scabs to large fissures with skin flaps or tags. A rough, fringed appearance of the lid may develop. The cause and significance of the syndrome is unknown, but certain strains of birds seem to have higher inci dence than others, suggesting a genetic component. Significant visual impairment is not often involved. Trauma/ Cannibalism Bright, shiny eyes can be an attractive target for picking by flock mates. Fortunately, most birds are very adept at protecting their heads from this assault, and eye injury due to picking rarely becomes a flock problem, particularly if beak trimming is practiced. Adequate vision is extremely important for all types of poultry to grow, thrive, and remain produc tive. Prompt attention to potential problems involving the eye, and proper diagnosis of eye/vision dis orders, can prevent minor prob lems from becoming major disasters.
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