Clinical ocular findings in cows with malignant catarrhal fever: ocular disease progression and outcome in 25 cases (2007-2010).

Objective:   To describe the ocular clinical signs in a group of cows diagnosed with sheep associated malignant catarrhal fever (MCF), and to investigate a possible correlation between the severity and progression of certain typical clinical signs and disease outcome.

Procedure:   This prospective study involved cows diagnosed with MCF between 2007 and 2010, and included cows enrolled in a larger clinical trial. Signalment of affected cows, presence and progression of ocular lesions, as well as disease outcome were recorded. Cows were divided into two groups based on the disease outcome: (1) survival and (2) nonsurvival. The degree of corneal edema at first examination was statistically compared between groups. The progression of corneal edema, uveitis and the examining ophthalmologists' subjective assessment of disease progression between the first and last examination were also compared between groups.

Results:   Twenty-five cows (22 F, 3 M) of six different breeds and one mixed breed were included. Median age was 21 months (range 8-113). Ten cows survived, 13 cows were euthanized, and two died. No statistical association was identified between the degree of corneal edema at the first examination and the disease outcome. Deterioration of corneal edema was not noticed in any of the surviving animals. Anterior uveitis improved in all 10 surviving cows.

Conclusions:   The degree of corneal edema at first examination had no prognostic value for the disease outcome. The results of this study suggest that the progression of corneal edema correlates well with disease outcome, and that nonimprovement of uveitis is a bad prognostic sign.