Prevalence of congenital hereditary sensorineural deafness in Australian Cattle Dogs and associations with coat characteristics and sex

Abstract

BackgroundCongenital hereditary sensorineural deafness (CHSD) occurs in many dog breeds, including Australian Cattle Dogs. In some breeds, CHSD is associated with a lack of cochlear melanocytes in the stria vascularis, certain coat characteristics, and potentially, abnormalities in neuroepithelial pigment production. This study investigates phenotypic markers for CHSD in 899 Australian Cattle Dogs.ResultsAuditory function was tested in 899 Australian Cattle Dogs in family groups using brainstem auditory evoked response testing. Coat colour and patterns, facial and body markings, gender and parental hearing status were recorded.Deafness prevalence among all 899 dogs was 10.8% with 7.5% unilaterally deaf, and 3.3% bilaterally deaf, and amongst pups from completely tested litters (n = 696) was 11.1%, with 7.5% unilaterally deaf, and 3.6% bilaterally deaf.Univariable and multivariable analyses revealed a negative association between deafness and bilateral facial masks (odds ratio 0.2; P ≤ 0.001). Using multivariable logistic animal modelling, the risk of deafness was lower in dogs with pigmented body spots (odds ratio 0.4; P = 0.050).No significant associations were found between deafness and coat colour.Within unilaterally deaf dogs with unilateral facial masks, no association was observed between the side of deafness and side of mask. The side of unilateral deafness was not significantly clustered amongst unilaterally deaf dogs from the same litter. Females were at increased risk of deafness (odds ratio from a logistic animal model 1.9; P = 0.034) after adjusting for any confounding by mask type and pigmented body spots.ConclusionsAustralian Cattle Dogs suffer from CHSD, and this disease is more common in dogs with mask-free faces, and in those without pigmented body patches. In unilaterally deaf dogs with unilateral masks, the lack of observed association between side of deafness and side of mask suggests that if CHSD is due to defects in molecular pigment pathways, the molecular control of embryonic melanoblast migration from ectoderm to skin differs from control of migration from ectoderm to cochlea. In Australian Cattle Dogs, CHSD may be more common in females.

Approaches to canine health surveillance

“…Brain stem auditory evoked response (BAER) testing distinguishes bilaterally and unilaterally hearing-impaired dogs from non-affected animals [ 161 ]. BAER data have been used to report prevalence estimates for deafness in Dalmatians [ 162 ], Border Collies [ 163 ] and Australian Cattle Dogs [ 164 ] as well as across multiple breeds [ 165 ]. These studies benefitted from well-defined case inclusion criteria and large study sizes but the voluntary submission process may have affected the presentation probabilities for known deaf individuals.…”

The Genetics of Deafness in Domestic Animals

“…The boxer Tasha that was used to sequence the canine genome had a phenotype designated as flash ( Ss w ), which enabled construction of BACs (bacterial artificial chromosomes) for each allele from her DNA ( 74 ). Significant associations between deafness and the recessive piebald alleles have been demonstrated for Dalmatian, English setter, and English cocker spaniel ( 75 ), border collie ( 76 , 77 ), Australian cattle dog ( 78 ), and Jack Russell terrier ( 79 ). It has also been shown that a strong relationship exists between deafness and the absence of pigment in the iris and tapetum lucidum, interpreted to be evidence of strong expression of the piebald locus ( 75 ).…”

Congenital sensorineural deafness in English setters in the United Kingdom: prevalence and association with phenotype and sex

“…Several studies have evaluated the prevalence of CSD in predisposed breeds in particular geographical areas 9 14–20. Prevalence ranges widely from 1.3 per cent in whippets9 to 30 per cent in dalmatians 9.…”

“…Some phenotypic characteristics have been found to be significantly associated with CSD in particular breeds of dog. These are generally traits associated with lack of pigmentation such as blue eyes or white coat 9 14 16 17 19. Some studies in dalmatians have reported a higher prevalence of CSD in females,21–24 but others25 26 have found no difference.…”