Congenital cataracts in an Ayrshire herd: a herd case report

Abstract

An Ayrshire dairy herd was investigated for occurrence of ocular abnormalities in new-born calves. Ophthalmic examinations were performed on all the animals in the herd and 26% of them were diagnosed with bilateral cataracts. Cataracts varied in extent and severity but the majority were restricted to the lens nucleus. Epidemiological analysis showed the prevalence was higher in male animals and lower in animals born to heifers. A family tree was designed but no genetic impact of dam lines was evident. Sire data was incomplete and could therefore not be included. Based on the information provided by the farmer there was no obvious environmental or nutritional cause of these cataracts. However, data records were incomplete and further investigation/monitoring of the herd would be needed to establish a cause and enable a better insight into the aetiology of this disease in cattle.

Figure 1

Photographs of calves with different severity of cataracts. A) Photograph of a calf with central demarcation (arrow pointing to the ring-like structure) around the nucleus (Group A); B) Photograph of a calf with a nuclear cataract (Group B); C) Photograph of a calf with a cataract extending into the perinuclear cortex (Group C).

Figure 2

Incidence of congenital cataracts by year of birth with a confidence interval of 95% (represented by error bars).

Figure 3

Family tree (dam line only). The red dots represent animals with cataracts, the green dots represent animals with no ocular abnormalities and the black dots represent the animals not examined (not in the herd). Data for sires was not available. Animals with cataracts are spread evenly across the diagram, suggesting there is no hereditary component.