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Pink Eye in Sheep

A very common condition affecting sheep characterized by severe inflammation of one or both eyes

Symptoms of the Disease/Condition.

The condition is caused by infection of the eye by infective agents Chlamydia and/or Mycoplasmaconjunctivae.species with secondary bacterial infection.

Most outbreaks are mild, affecting adult sheep during the summer and autumn. However, outbreaks can be severe and affect sheep of any age.

Risk factors include dust, pollen in grass, and flies. It is common in flocks which are being fed hay and in dry warm weather when large numbers of flies and dusty farm conditions predominate. The watery secretions seen in the early infection stages are very contagious. Spread through a flock is rapid.

The appearance of Pinkeye in sheep can be confused with grass seed or barley grass contamination of the eye and entropion (inverted eyelids) in young lambs.

The Impact.

Outbreaks may be severe in some flocks with as many as 50% of the flock affected. More commonly 10-15% of the flock is affected. The condition can be significant when it affects pregnant ewes making feeding difficult and often leading to metabolic disease prior to lambing. Where ewe deaths occur prior to lambing, the cost of a 1% increase in ewe wastage may be as high as $4.50 per ewe in a flock scanning 170%.

Management and Control.

In most cases recovery commences within 3-4 days and is complete in 10-14 days although in some animals the cloudiness of the cornea may persist for several weeks or even permanently. Carrier animals are common where the Chlamydia organism persists well after an outbreak. It is thought more than 50% of recovered animals remain resistant for periods of up to a year.

Because recovery of the condition is quick and spontaneous in Chlamydia caused pinkeye, it is often questionable whether treatment and isolation of infected sheep is warranted.