Influence of selective breeding on the Prevalence of chorioretinal dysplasia and coloboma in the rough collie in Sweden

Abstract

A total of 8204 rough collies, representing 76 per cent of all collies registered by the Swedish Kennel Club between 1989 and 1997, were examined before 10 weeks of age for collie eye anomaly (CEA). All dogs were permanently identified and examination results were registered and computerised. The policy of breeders during the study period was to select against coloboma in breeding stock, but to allow breeding of chorioretinal dysplasia (CRD) affected animals. The prevalence of CRD increased significantly from 54.2 per cent to 68.1 per cent (P < 0.001) from 1989 to 1997, while the prevalence of coloboma did not (8.3 per cent to 8.5 per cent, P = 0.4). These results are not compatible with a simple, recessive, autosomal inheritance for the entire CEA complex.

Compliance between clinical and genetic diagnosis of choroidal hypoplasia in 103 Norwegian Border Collie puppies

“…Wallin‐Håkanson et al . described that CH/CRD and colobomas were inherited as separate traits and that a polygenetic mode of inheritance of CEA was suspected . Lowe et al .…”

Collie eye anomaly in Hokkaido dogs: case study

“…Many studies have been performed to determine the mode of inheritance for this syndrome 3,6–12 . Variability in the severity and expression of the disease is well recognized in the CEA phenotype and suggests that CEA may be a complex trait with multiple genetic contributors 5 .…”

Bilateral typical complete colobomas in a donkey: Retinographic and fluorangiographic description

“…Complications and severity vary depending on the location and size of the coloboma ranging from small iris coloboma without clinical relevance to a wide retinochoroidal and optic disk defect causing blindness 2 . Typical colobomas has been described in mices, 3 rats, 4 cats, 5 collie dogs, 6 snow leopards, 7 lambs, 8 cattle, 9,10 and horses 11–15 . There are few reports of typical colobomatous defects in horses and to the authors’ knowledge it has not been previously described in the donkey.…”