Infectious Keratoconjunctivitis (Pinkeye, Infectious ophthalmia)
Description Infectious keratoconjunctivitis (pinkeye) caused by MORAXELLA BOVIS is one of the most common bovine ocular diseases. Cattle are the only reservoir for M. BOVIS. Corneal ulceration starts in the center of the cornea. Synechia and glaucoma can follow an acute attack. M. OVIS is a common isolate from affected eyes but has not been shown to be a primary pathogen.
Infectious Keratoconjunctivitis (Pinkeye, Infectious ophthalmia)Infectious keratoconjunctivitis of cattle, sheep, and goats is characterized by blepharospasm, conjunctivitis, lacrimation, and varying degrees of corneal opacity and ulceration.In cattle, Moraxella bovis with multiple serovars is the most commonly recognized cause of infectious keratoconjunctivitis. Most other ocular infections of cattle are characterized by conjunctivitis and minimal or absent keratitis. The primary differential diagnosis is infectious bovine rhinotracheitis (IBR), which causes severe conjunctivitis and edema of the cornea near the corneoscleral junction, but corneal ulceration is uncommon. Other organisms that may cause conjunctivitis of cattle, either alone or in conjunction with M bovis , include Mycoplasma spp and Neisseria spp . Infection with IBR or other microbes may increase the severity of infection with M bovis . In sheep, infection with Chlamydophila ( Chlamydia ) pecorum is most common. Nonchlamydophilal infections may be caused by rickettsia-like organisms ( Colesiota conjunctivae ), Mycoplasma spp , and aerobic bacteria, notably Neisseria ovis . In goats, mycoplasmal infections are most common, although aerobic bacteria also have been isolated. Although much of the syndrome in young goats is caused by Mycoplasma agalactiae.
In all species, presumptive diagnosis is based on ocular signs and concurrent systemic disease. It is important to distinguish that the lesions are not due to foreign bodies or parasites (see eyeworms of large animals , Eyeworms of Large Animals). In IBR, upper respiratory signs and conjunctivitis predominate, while keratitis accompanied by ulceration is rare. In bovine malignant catarrhal fever, respiratory signs are prominent with primary uveitis and associated keratitis. Microbial culture may be beneficial in confirming the causative organisms. Chlamydophila and Mycoplasma spp require special media; the diagnostic laboratory should be consulted prior to sample collection. Cytologic evaluation of stained slides prepared from conjunctival scrapings of sheep and goats may reveal Chlamydophila or Mycoplasma organisms. However, the intracytoplasmic inclusion bodies can be difficult to recognize. PCR analysis can be used to detect Chlamydophila and Mycoplasma spp .