Kvet Forum
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This is a highly contagious disease that can spread rapidly during warm seasons of the year. IBK is seen in cattle worldwide and has significant economic consequences in some countries.
Aetiology
Moraxella bovis is considered to be the cause of the disease. Flies act as mechanical vectors for M. bovis and sunlight and dust are risk factors. The clinical signs are exacerbated by concurrent Infectious Bovine Rhinotracheitis (IBR) virus infection.
Clinical Presentation
The condition can be either unilateral or bilateral. Most cases are selected for treatment on the basis of obvious epiphora, with tear staining of the face initially serous, but becoming increasingly purulent and matting the lashes and hair of the face.
On closer examination of the affected eye(s) there is a marked conjunctivitis with injected tortuous scleral vessels and hyperaemic conjunctivae.
There is marked photophobia with blepharospasm when cattle are exposed to bright sunlight.
More advanced cases show keratitis and corneal ulceration. The ocular lesions are very painful and disrupt grazing patterns and this can cause poor performance and even weight loss.
Bilateral lesions cause temporary blindness accompanied by aimless wandering.
Spontaneous recovery starts in mild cases 3–5 days after clinical signs are first observed and is complete two weeks later. In severe neglected cases, ulceration may progress to corneal perforation and panopthalmitis.
Differential Diagnosis
These include:
- Foreign bodies (e.g. grass awns) within the conjunctival sac.
- Bovine iritis and
- IBR.
Diagnosis
Diagnosis is based on the clinical examination and response to antibiotic therapy. Bacteriological isolation is rarely undertaken.
Management
Prompt treatment is essential. Topical ophthalmic antibiotic cream/powders containing cloxacillin/oxytetracycline are commonly used by farmers.
Antibiotic injection (penicillin, oxytetracycline or ceftiofur) into the dorsal bulbar conjunctiva is the best treatment, but this can be difficult to achieve in fractious adult cattle and requires good restraint.
When subconjunctival or topical treatment is not practical, single-dose long-acting oxytetracycline, florfenicol, tilmicosin and tulathromycin have all been reported to be effective.
In severe cases, in order to provide protection from environmental conditions , suturing the eyelids together using mattress sutures can be undertaken under local anaesthesia together with an auriculopalpebral block. Adhesive eye patches can also be used.
Fly control using pour on insecticides is never absolute and repeated treatments prove costly.