ARTICLE BY DR.S.K.MAINI

Eye disorders are seen very frequently in Emu's, as the birds rely heavily on their sense of sight to carry on their daily activities, an increased incidence of eye problems can result in several types of complicationhs, a visually impaired bird is at a major disadvantage in competing for food , water, and social position in a population of birds.

Some of the common problems are listed below with their prevention/treatments.

Non-Infectious Causes

1.   Nutritional Deficiencies

Certain vitamin deficiencies, such as vitamin A and vitamin E, can result in damage to the eye.  Vitamin A is necessary for the production of visula pigment of the retina and for maintenance of the lining of the tear ducts.  Vitamin E si necessary for maintenance of the lens protein in the developing embryo.  Vitamin E is passed from the breeder hen to the egg.  If the breeder is receiving inadequate vitamin E in the diet, the embryo will suffer from a vitamin E deficiency and possible blindness.  Vitamin deficiencies are rare when well balanced commercial feeds are used.

2.  Developmental Disorders

Genetic or Congenital abnormalities in the formation and placement of the eye and eye socket occur, but the incidence is low.  Abnormalities seen include one or both eyes missing, eyes reduced in size or placed forward on the head.  These abnormalities may be hereditary or may be due to improper preincubation or incubation conditions.  Affected chicks should be culled at the hatchery.

3.  Cataracts

A high incidence of cataracts can occur in Emu flocks with vitamin E deficiency equine encephalomyelitis infection, or continuous exposure to some types of artificial lighting.

4.  Trauma

Injury to the eye and surrounding structures can occur in the hatchery, during, trasportation to th far, or on the farm by poorly maintained equipment.  Bright , shiny eyes can be an attractive target for picking by flock mates.  Most chicks, however, are very adept at protecting their heads so that eye injury due to picking is rarely a problem. If seen the chick/bird should be separated and approximately attended.

5.   Ammonia Toxicity

Ammonia gas is extremely irritating to the membranes that line the eyelids, eyes,s insues and trachea.  Conjunctiitis is inflammation of the conjuctiva (membrances that line the eyelids) and the exposed sclera (white part of the eye).  Affected birds have redened, swollen eyelids, and are sensitive to and avoid light. If high ammonia levels persist, the cornea, the outermost part of the front of the eyeball, becomes ulcertated and blindness may occur.

Ammonia gas is a bacterial breakdown product produced when uric acid from manure combines with water forming a suitable environment for bacterial growth.  Bacterial growth, and the resulting NH3 p roduction is also dependent upon litter  or manure PH and temperature.

In Intensive production systems (brooding rooms) high levels of ammonia gas buildup are associated with inadequate ventilation. Ammonia is not typically a problem for irds raised outdoors.  Change of litter , sprinkling of lime powder and improving the ventilation are suggested.

Infectious Causes -

1.   Avian Pox

Avian pox is a viral disease that affects many types of birds including Emu's Fowl pox primarily affects chickens and turkeys.  Pigeon pox affects pigeons, chickens, turkeys, ducks, and geese.  Canary pox infects canaries, chickens, sparrows, and probably other species.

Pox is characterized by raised, blister like lesions that develop on unfeathered areas (head,legs,vent, etc) of the birds. If the lesions are around the eyes, then swelling may occur with impairment of eyesight and possibly blindness in severe cases.  Ordinarily, the eyeball itself remains unaffected and, once lesions are resolved, eyesight should return to normal.  Pox vaccine for poultry