Bovis ISSN 2398-2993

Infectious bovine keratoconjunctivitis

Synonym(s): Pink eye, infectious ophthalmia

Contributor(s): Ash Phipps , Paul Wood

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Introduction

  • Cause: primary pathogen Moraxella bovis. Secondary pathogens Morexella lacunata, Morexella catarrhalis and Morexella bovoculi.
  • Signs: photophobia, blepharospasm and profuse ocular discharge (unilateral/bilateral).
  • Diagnosis: generally based on clinical signs, however, culture of the organism would be definitive.
  • Treatment: mild cases can be treated topically or parenterally. For severe cases more intensive treatment may be required.
  • Prognosis: good: up to 98% of cases can spontaneously recover. However, 2 % of cases can result in loss of the eye if left untreated.

Pathogenesis

Etiology

  • Moraxella bovis Moraxella bovis is a blunt ended gram negative bacillus
    • Has surface pili and haemolytic endotoxin (cytolysin) with corneotoxic properties.

Predisposing factors

General

  • Damage to the cornea.
  • Exposure to ultraviolet light.

Specific

  • Less pigment around the eye.
  • The presence of flies that carry the organism.
  • Dusty conditions particularly over summer.
  • Long grass that could cause trauma to the cornea and transmission of the organism.
  • Close proximity to wooded areas.
  • Vaccination with a live IBR Infectious bovine rhinotracheitis vaccine may increase risk due to increases in ocular discharge following vaccine administration

Pathophysiology

  • The organism, Moraxella bovis, attaches to the corneal epithelium by the pilus antigen.
  • Initial corneal erosion occurs with little inflammatory response.
  • Cytotoxicity effects of the organism lead to the production of a corneal ulceration. Resulting in destruction of the corneal epithelium and keratanocytes and severe inflammation of the eye.
  • As the lesion on the eye develops, the corneal ulceration deepens leading to further inflammation, edema and neovascularization.
  • Healing results in a formation of an extensive scar that can permanently impair vision.
  • Severe lesions may lead to globe rupture.
  • Initial lesions are central corneal ulcers that rapidly enlarge and become vascularized (5-7 d post infection). Lesions may also develop to demonstrate granulation tissue protrusion and purulent discharges.

Timecourse

  • Incubation period is approximately 2 to 3 days but can be as long as several weeks.
  • Erosion of the cornea occurs within 12 hours of infection.
  • Corneal opacity occurs 1 to 2 days.
  • Ulceration of the cornea occurs within 4 days.
  • After approximately 6 days post incubation period the whole globe may be affected (corneal vascularization).
  • Resolution of the infection occurs within 3 to 5 weeks.

Epidemiology

  • Cattle of all ages can become infected.
  • Rapidly spreads through naïve herds.
  • Generally there will be multiple animals affected at time.
  • The source within a herd is typically a carrier animal.
  • Most commonly seen in the autumn and summer seasons.
  • Under rare circumstances, the disease can be seen in animals in winter with animals housed in close proximity, such as feedlots.
  • The disease has no mortality rate.
  • The morbidity rate within some herds can be >80%.
  • Each animal may be unilaterally or bilaterally affected.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • McConnel C S, Shum L & House J K (2007) Infectious bovine keratoconjunctivitis antimicrobial therapy. Australian Veterinary Association 85 (1 &2), 65-69.
  • McConnel C S & House J K (2005) Infectious bovine keratoconjunctivitis vaccine development. Australian Veterinary Association 83 (8), 506-510 PubMed.
  • Abeynayake P & Cooper B S (1989) The concentration of penicillin in bovine conjunctival sac fluid as it pertains to the treatment of Moraxella bovis infection. (I) Subconjunctival injection. Journal of veterinary pharmacology and therapeutics 12 (1), 25-30 PubMed.

Other sources of information

  • Parkinson T J, Vermunt J J & Malmo J (2010) Diseases of cattle in Australasia: a comprehensive textbook. New Zealand Veterinary Association Foundation for Continuing Education, Wellington, NZ, pp 616-619.
  • Radostits O M, Gay C C, Blood D C & Hinchliff K W (2006) Veterinary Medicine. A Textbook of the Diseases of Cattle, Sheep, Pigs, Goats and Horses. 7th edn. Saunders, China. pp: 994-997.


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