Prevalence of unilateral and bilateral deafness in border collies and association with phenotype.
BACKGROUND
Congenital sensorineural deafness (CSD) occurs in Border Collies, but its prevalence and inheritance are unknown. This study estimated the prevalence of CSD in Border Collies and investigated its association with phenotypic attributes linked to the merle gene, including coat pigmentation and iris color.


OBJECTIVE
Deafness in Border Collies is associated with pigmentation patterns linked to the merle gene.


METHODS
A total of 2597 Border Collies from the United Kingdom.


METHODS
A retrospective study of Border Collies tested, during 1994-2002, by using brainstem auditory evoked responses. Associations between deafness and phenotypic attributes were assessed by using generalized logistic regression.


RESULTS
The prevalence of CSD in puppies was estimated as 2.8%. The corresponding rates of unilateral and bilateral CSD were 2.3 and 0.5%, respectively. Adjustment for clustering of hearing status by litter reduced the overall prevalence estimate to 1.6%. There was no association between CSD and sex (P = .2). Deaf Border Collies had higher rates of merle coat pigmentation, blue iris pigment, and excess white on the head than normal hearing Border Collies (all P < .001). The odds of deafness were increased by a factor of 14 for Border Collies with deaf dams, relative to the odds for dogs with normal dams (P = .007), after adjustment for phenotypic attributes.


CONCLUSIONS
Associations between CSD and pigmentation patterns linked to the merle gene were demonstrated for Border Collies. Evidence for an inherited component to CSD in Border Collies supports selective breeding from only tested and normal parents to reduce the prevalence of this disease.
Platt
Simon
S
Centre for Small Animal Studies, Animal Health Trust, Lanwades Park, Kentford, Newmar- ket, Suffolk CB8 7UU, UK. Simon.platt@aht.org.uk
Freeman
Julia
J
di Stefani
Alberta
A
Wieczorek
Lara
L
Henley
William
W
D000367:Age Factors; D000818:Animals; D001947:Breeding / Q000379:methods; D003638:Deafness / Q000453:epidemiology / Q000235:genetics / Q000662:veterinary*; D004283:Dog Diseases / Q000453:epidemiology* / Q000235:genetics*; D004285:Dogs; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005127:Eye Color; D005260:Female; D005838:Genotype; D008297:Male; D010375:Pedigree; D010641:Phenotype; D010858:Pigmentation; D015995:Prevalence; D012189:Retrospective Studies; D012737:Sex Factors