A genome-wide significant association on chromosome 15 for congenital entropion in Swiss White Alpine sheep

Comparison of entropion outcome with and without intervention in Romane and Ile de France sheep breeds

BACKGROUND

Congenital entropion is the most frequent ocular disorder in newborn lambs of certain sheep breeds, which, if not treated, can result in complete blindness and death due to starvation.

OBJECTIVES

The aims of this study were to compare the spontaneous healing of entropion in two breeds and assess the outcome of cases with and without therapeutic intervention.

METHODS

A total of 158 entropion cases (119 Ile de France and 39 Romane) were investigated, and swab samples were collected from the cornea and conjunctiva of 73 of the affected lambs for bacteriological investigation. In addition, an ocular intervention was carried out in 123 affected animals.

RESULTS

The Romane breed developed entropion at an average age of 7 days compared to the Ile de France, which developed it at an average age of 1 day. Likewise, significant differences were found between bilateral and unilateral involvement in both breeds. Meanwhile, 22.1% of cases recovered spontaneously, and the highest rate of spontaneous recovery without intervention was observed in the Romane breed (66%). Bacteria isolated from ocular samples included Staphylococcus spp. (42.5%), Bacillus spp. (21.9%), Trueperella pyogenes (13.7%), Corynebacterium spp. (12.3%) and Escherichia coli (9.6%).

CONCLUSIONS

The results of the study showed that the onset time of entropion, bilateral involvement, the severity of the process and the need for re-treatment were higher in the Ile de France breed than in the Romane breed. Likewise, the Romane breed showed a higher degree of spontaneous recovery of entropion.

Molecular Cytogenetics in Domestic Bovids: A Review

The discovery of the Robertsonian translocation (rob) involving cattle chromosomes 1 and 29 and the demonstration of its deleterious effects on fertility focused the interest of many scientific groups on using chromosome banding techniques to reveal chromosome abnormalities and verify their effects on fertility in domestic animals. At the same time, comparative banding studies among various species of domestic or wild animals were found useful for delineating chromosome evolution among species. The advent of molecular cytogenetics, particularly the use of fluorescence in situ hybridization (FISH), has allowed a deeper investigation of the chromosomes of domestic animals through: (a) the physical mapping of specific DNA sequences on chromosome regions; (b) the use of specific chromosome markers for the identification of the chromosomes or chromosome regions involved in chromosome abnormalities, especially when poor banding patterns are produced; (c) better anchoring of radiation hybrid and genetic maps to specific chromosome regions; (d) better comparisons of related and unrelated species by comparative FISH mapping and/or Zoo-FISH techniques; (e) the study of meiotic segregation, especially by sperm-FISH, in some chromosome abnormalities; (f) better demonstration of conserved or lost DNA sequences in chromosome abnormalities; (g) the use of informatic and genomic reconstructions, in addition to CGH arrays, to predict conserved or lost chromosome regions in related species; and (h) the study of some chromosome abnormalities and genomic stability using PCR applications. This review summarizes the most important applications of molecular cytogenetics in domestic bovids, with an emphasis on FISH mapping applications.