Unilateral and Bilateral Congenital Sensorineural Deafness in Client-Owned Pure-Breed White Cats

Background: Congenital sensorineural deafness has been reported frequently in experimental mixed-breed white cats but there is a paucity of data on occurrence of deafness in client-owned pure-breed white cats.
Objective: To describe hearing status in client-owned pure-breed white cats.
Animals: Eighty-four pure-breed client-owned cats with white coat color of 10 registered breeds presented for routine hearing evaluation before breeding (1995–2008).
Methods: Hearing was assessed by click-evoked brainstem auditory evoked response.
Results: Overall deafness prevalence was 20.2%; 9 cats (10.7%) were bilaterally deaf and 8 cats (9.5%) were unilaterally deaf. There was no association between sex and deafness status ( P = .85). Deafness status was associated with iris color ( P = .04).
Conclusions and Clinical Importance: Congenital sensorineural deafness frequently occurs in pure-breed cats with white coat color. Unilateral sensorineural deafness was as common as bilateral deafness.     

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. HYPOTHESIS: Deafness in Border Collies is associated with pigmentation patterns linked to the merle gene. ANIMALS: 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 AND CLINICAL IMPORTANCE: 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.     

Brainstem Auditory-Evoked Potential Assessment of Congenital Deafness in Dalmatians: Associations With Phenotypic Markers

To screen for congenital deafness, brainstem auditory-evoked potential (BAEP) testing was performed on 1031 Dalmatians from three geographically separated areas. Phenotypic marker assessment was done to determine markers possibly associated with deafness. Markers included sex, hair coat color, pigmentation of different areas of skin (eye rims, nose, and ears), presence of a patch, spot size and marking (density of spotting), sire and dam BAEP status, and presence of iris and retinal tapetal pigmentation. Combined data from all test sites showed 8.1% bilateral deafness (N = 83 dogs) and 21.6% unilateral deafness (N = 223), or an overall 29.7% incidence of hearing disorders. Significant (P less than 0.05) associations with deafness for the data from all test sites combined were seen for patch, sire and dam BAEP, iris pigment, and retinal pigment. However, results differed for several of the significant phenotypic markers when analyses were done on the data from the individual test sites; changes from significant to not significant were found. This suggested the existence of multiple populations of deafness patterns, and reinforced the precautionary conclusion that associations of phenotypic markers with deafness are not necessarily functionally significant.     

Normative auditory brainstem response data for hearing threshold and neuro-otological diagnosis in the dog

There Is growing Interest In the application of auditory brainstem response (ABR) audlometry for hearing assessment In dogs. The technique is far from standardised, however, resulting In large discrepancles between studies. This study aimed to obtain normative data, under clearly defined conditions, for two breeds of significantly different size; head size being a potential factor determining ABR latency values. The subjects, 20 daimatians and 20 Jack Russell terriers, were sedated prior to ABR testing, and subcutaneous scalp electrodes used to detect the evoked potential ellclted by a click stimulus presented via Insert earphones. The mean ABR thresholds for the two breeds, 0 and -5 decibels re normal hearing level (dB nHL), respectively, were very simllar to those for humans. The latency values of the main ABR waves and the Interval between them were statistically significantly smaller for the smaller breed, but there was no correlation with head size within either breed. The results provide a baseline to assist with confirmation of hearing Impalrment and neuro-otological diagnosis In the dog.     

Prevalence of Deafness in Dogs Heterozygous or Homozygous for the Merle Allele

Background: Deafness in dogs is frequently associated with the pigment genes piebald and merle. Little is known about the prevalence of deafness in dogs carrying the merle allele.
Objective: To determine the prevalence of deafness in dogs heterozygous and homozygous for the merle allele of the mouse Silver pigment locus homolog (SILV) gene.
Animals: One hundred and fifty-three privately owned merle dogs of different breeds and both sexes.
Methods: Hearing was tested by brainstem auditory-evoked response and classified as bilaterally hearing, unilaterally deaf, or bilaterally deaf. DNA from buccal cells was genotyped as either heterozygous or homozygous for the merle allele. Deafness association tests among merle genotype, eye color, and sex were performed by the χ² test.
Results: Deafness prevalence in merles overall was 4.6% unilaterally deaf and 4.6% bilaterally deaf. There was a significant association between hearing status and heterozygous versus homozygous merle genotype. For single merles ( Mm ), 2.7% were unilaterally deaf and 0.9% were bilaterally deaf. For double merles ( MM ), 10% were unilaterally deaf and 15% were bilaterally deaf. There was no significant association with eye color or sex.
Conclusions: Deafness prevalence in merle dogs was greater than that in some dog breeds homozygous for the piebald gene, such as the English Cocker Spaniel, but comparable to, or lower than, that in the Dalmatian and white Bull Terrier. Dogs homozygous for the merle allele were significantly more likely to be deaf than heterozygotes.     

Congenital sensorineural deafness in dogs: a molecular genetic approach toward unravelling the responsible genes

Deafness is often diagnosed in different dog breeds and has been identified as a significant problem for breeders, owners and clinicians. The aetiology can be inherited or acquired, and a distinction must be made between sensorineural and conductive forms of deafness. This paper provides a brief overview of the varieties of findings in different dog breeds and in one breed in particular including prevalence, phenotypic and gender associations, histology, modes of inheritance and the number of contributing genes in congenital sensorineural deafness. We have also described molecular genetic approaches to canine hearing loss and discuss how comparative genomics could help reduce the prevalence of deafness in affected breeds leading to new insights into the molecular mechanisms of auditory function in both dogs and humans.     

Complex segregation analysis of deafness in Dalmatians

OBJECTIVE: To use pedigree analysis to evaluate the feasibility of a major locus model for deafness in Dalmatians. ANIMALS: 605 purebred Dalmatians from 42 families. PROCEDURE: Hearing loss was evaluated through the brainstem auditory-evoked response. Dogs were classified into mutually exclusive categories: normal hearing, unilaterally deaf, or bilaterally deaf. Information was collected on sex, coat color, presence or absence of a color patch at birth, and eye color. Statistical analyses were performed by use of regressive logistic models designed for complex segregation analysis. Genetic correlations among eye color, deafness, and color patch were estimated. RESULTS: Prevalence of hearing loss was 11% for dogs classified as unilaterally deaf and 5% for dogs that were bilaterally deaf. Complex segregation analysis detected statistical evidence of a single allele with an expected frequency of 0.21 that had an effect on the prevalence of deafness. Results of analyses suggested that this locus cannot completely explain the inheritance and incidence of deafness in Dalmatians. Genetic correlation estimates among deafness, eye color, and color patch revealed strong interrelationships among these characteristics. CONCLUSIONS AND CLINICAL RELEVANCE: To reduce the incidence of hearing loss in Dalmatians, unilaterally deaf, blue-eyed dogs should not be considered as potential parents.     

'Continuous muscle fibre activity' in six dogs with episodic myokymia, stiffness and collapse

Continuous muscle fibre activity was observed in a crossbred dog, a Yorkshire terrier, a border collie and three Jack Russell terriers. The clinical signs consisted of episodes of generalised myokymia which developed into muscle stiffness and delayed muscle relaxation and generally led to the dogs collapsing into lateral recumbency. These episodes were preceded by intense facial rubbing in three of the dogs, and were associated with severe hyperthermia in five of them. All three Jack Russell terriers showed continuous ataxia. The dogs had above normal activities of aspartate aminotransferase, alanine aminotransferase and creatine kinase, but their cerebrospinal fluid was normal. Myokymic discharges were observed by electromyography in two of the dogs. Two of them were treated with membrane-stabilising agents, with variable results.     

A KCNJ10 mutation previously identified in the Russell group of terriers also occurs in Smooth-Haired Fox Terriers with hereditary ataxia and in related breeds

Background

Hereditary ataxias with similar phenotypes were reported in the Smooth-Haired Fox Terrier, the Jack Russell Terrier and the Parson Russell Terrier. However, segregation analyses showed differing inheritance modes in these breeds. Recently, molecular genetic studies on the Russell group of terriers found independent mutations in KCNJ10 and CAPN1, each associated with a specific clinical subtype of inherited ataxia. The aim of this study was to clarify whether or not Smooth-Haired Fox Terriers with hereditary ataxia and dogs of other related breeds harbor either of the same mutations. A sub goal was to update the results of KCNJ10 genotyping in Russell group terriers.

Findings

Three Smooth-Haired Fox Terriers with hereditary ataxia and two Toy Fox Terriers with a similar phenotype were all homozygous for the KCNJ10 mutation. The same mutation was also found in a heterozygous state in clinically unaffected Tenterfield Terriers (n = 5) and, in agreement with previous studies, in Jack Russell Terriers, Parson Russell Terriers, and Russell Terriers.

Conclusions

A KCNJ10 mutation, previously associated with an autosomal recessive spinocerebellar ataxia in Jack Russell Terriers, Parson Russell Terriers, and Russell Terriers segregates in at least three more breeds descended from British hunting terriers. Ataxic members of two of these breeds, the Smooth-Haired Fox Terrier and the Toy Fox Terrier, were homozygous for the mutation, strengthening the likelihood that this genetic defect is indeed the causative mutation for the disease known as “hereditary ataxia” in Fox Terriers and “spinocerebellar ataxia with myokymia, seizures or both” in the Russell group of terriers.     

贵州地方猪品种毛色与KIT基因拷贝数之间的关联分析

为了研究KIT基因的拷贝数与贵州地方猪毛色之间的关系,本试验以黔北黑猪、柯乐猪、糯谷猪、香猪4个地方品种为试验材料,采用实时荧光定量PCR方法检测基因组中KIT基因的拷贝数变异,并与荣昌猪和大白猪2个白毛色猪品种相比较.结果显示,4个贵州地方猪种中,全黑/全棕毛色个体的KIT基因拷贝数以缺失为主,黑色带白斑个体的KIT基因拷贝数全部缺失,而棕色带白个体的KIT基因拷贝数增加、正常各半.大白猪的KIT基因拷贝数显著增加,荣昌猪KIT基因拷贝数以正常类型为主.表明大白猪的白毛色由KIT基因拷贝数增加决定,但荣昌猪的白毛色可能与KIT基因的拷贝数变异之间没有直接的联系;4个贵州地方品猪的全黑/全棕色毛色与KIT基因拷贝数的缺失有关,但柯乐猪和香猪中带白斑个体的KIT基因拷贝数并未增加,提示贵州地方猪品种的白斑毛色的形成机制有一定的特殊性.     

Normative auditory brainstem response data for bone conduction in the dog

Auditory brainstem response (ABR) is a valuable tool for the diagnosis of hearing disorders in dogs, but is hampered by the lack of published normative data. The aim of the present study was to obtain normative data for bone conduction, without masking, under clearly defined conditions. Subjects comprised 20 Dalmatians and 20 Jack Russell terriers. Two methods were investigated: holding the bone vibrator against the head by hand or by applying a 500 g weight. The results revealed no difference in hearing threshold between the two breeds or for the two methods of applying the bone vibrator to the head. The mean hearing threshold was close to 0 decibels re normal hearing level (dB nHL), which is the biological norm for humans. Hence, bone conduction thresholds can be used for confirmation of conductive hearing impairment in the dog, in the same way as in humans.     

Brainstem auditory-evoked potential assessment of auditory function and congenital deafness in llamas (Lama glama) and alpacas (L. pacos)

Auditory function of llamas and alpacas was assessed objectively by means of brainstem auditory-evoked response audiometry (BAER) to establish the normal hearing range and to test the hypothesis of a correlation between blue eyes, white coat, and deafness. Sixty-three camelids were available for the study. Thirteen animals had blue irides; 1 animal had 1 blue and 1 pigmented iris. Wave latencies, amplitudes, and interpeak latencies were measured under general anesthetic. Click stimuli (dB [HL]) were delivered by an insert earphone. Four to five positive peaks could be detected; waves I, II, and V were reproducible; wave II appeared infrequently; and wave IV generally merged with wave V to form a complex. Peak latencies decreased and peak amplitudes increased as stimulus intensity increased. A hearing threshold level of 10-20 dB (HL) was proposed as the normal range in llamas and alpacas. None of the animals with pigmentation of coat and iris showed any degree of hearing impairment. Seven of the 10 blue-eyed, pure-white animals were bilaterally deaf and one of them was unilaterally deaf. However, 2 blue-eyed, white animals exhibited normal hearing ability. Three blue-eyed animals with pigmented coat did not show any hearing impairment. All white animals with normal iris pigmentation had normal auditory function; so did the 1 animal with 1 normal and 1 blue iris. The high frequency (78%) of bilaterally deaf animals with pure white coat and blue iris pigmentation supports the hypothesis of a correlation between pigmentation anomalies and congenital deafness in llamas and alpacas.     

ADAMTS17 mutation associated with primary lens luxation is widespread among breeds

Primary lens luxation (PLL) is a well-recognized, painful and potentially blinding inherited ocular condition in dogs. We screened PLL-affected dogs of 30 different breeds, to identify those which carried a previously described c.1473+1 G>A mutation in ADAMTS17 that is associated with PLL in Miniature Bull terriers, Lancashire Heelers, and Jack Russell terriers. This ADAMTS17 mutation was identified in PLL-affected dogs from 14 additional breeds. PLL-affected dogs from some breeds (most notably the Shar pei and the Brittany spaniel) did not carry the G1473+1A ADAMTS17 mutation, indicating they must suffer from a genetically distinct form of the condition. We also estimated the frequency of this ADAMTS17 mutation in some of the breeds. Our findings indicate the mutation segregates in a large number of different breeds of dog, many of which are terriers or breeds with terrier co-ancestry, but some of which have more diverse origins. Our results also indicate that the mutation is present at high frequency within most of the breeds in which it segregates. In the miniature bull terrier breed estimates of mutation frequency ranged from 0.27 to 0.39, corresponding to 7.3-15.2% PLL-affected dogs in this breed. We also identified an increased risk of PLL associated with heterozygosity at ADAMTS17, suggesting that carriers carry a low risk of developing PLL.     

Prevalence of respiratory signs and identification of risk factors for respiratory morbidity in Swedish Yorkshire terriers

Yorkshire terriers may be prone to respiratory disease; however, limited epidemiological information is available. A cross-sectional study design was used to compare the prevalence of respiratory signs in Yorkshire terriers with the prevalence in a population of dogs in general and to identify risk factors for respiratory clinical signs within the Swedish population of Yorkshire terriers. Data on clinical signs and risk factors were obtained from a questionnaire. The prevalence of respiratory signs in general (RS) was significantly higher among Yorkshire terriers compared with control dogs (RS 56.3 per cent and 23.0 per cent), and likewise more frequent respiratory signs (FRS) (26.0 per cent and 5.0 per cent). Age, sex and breed were shown to be significant risk factors, and an interaction between age and sex was discovered. The study indicated a sex ratio reversal in the prevalence of RS - the probability of females having RS increased with advancing age, while the probability for males was fairly constant.     

Case Report Cutaneous vasculitis in five Jack Russell Terriers

Abstract A new, possibly breed associated, vasculitis of Jack Russell Terriers is described. Lesions include alopecia and focal crusted ulcers of the distal extremities and bony prominences. Histopathological lesions include single cell necrosis of the epithelium, pigmentary incontinence, leucocytoclastic vasculitis and ischaemic degeneration of hair follicles. Dermal oedema and an infiltrate of lymphocytes and/or macrophages are often seen. Clinically and histopathologically the disease most closely resembles dermatomyositis of Collies and Shetland sheepdogs but the obvious breed discrepancy makes systemic lupus erythematosus the most likely differential diagnosis. Dapsone and anti-inflammatory doses of prednisone have proved to be satisfactory treatments. Résumé— Une nouvelle dermatose à prédisposition raciale, de type vascularite est décrite chez des jack russel terriers. Les lésions cliniques incluent une alopécie, des ulcèrations focales et croûteuses des extrémités distales et des points de pression. Les lésions histolopathologiques montrent des nécroses isolées des kératinocytes, une incontinence pigmentaire, une vascularite leucocytoclasique et une dégénérescence ischémique des follicules pileux. Un oedème dermique et une infiltration lymphocytaire et/ou macrophagique sont également observés. Sur les plans clinique et histopathologique, cette maladie ressemble plus aux dermatomyosites du Colley et du Shetland, mais la discordance raciale évidente fait du lupus érythémateux systémique le diagnostic différentiel le plus vraisemblable. La dapsone et la prednisone à dose antiinflammatoire sont des traitements satisfaisants. [Parker, W.M., Foster, R.A. Cutaneous vasculitis in five Jack Russell Terriers (Vascularite cutanée chez 5 jack russel terriers). Veterinary Dermatology 1996; 7 : 109–115.] Resumen Se describe una vasculitis nueva, posiblemente asociada a la raza en el terrier Jack Russell. Las lesiones incluyen alopecia y ulceraciones costrosas en las extremidades distales y en prominencias óseas. Las lesiones histopatológicas incluyen necrosis celular individual del epitelio, incontinencia pigmentaria, vasculitis leucocitoclástica y degeneración isquémica de los foliculos pilosos. Con frecuencia se observa edema dérmico y una infiltración por linfocitos y/o macrófagos. Este cuadro se asemeja clinica e histopatológicamente a la dermatomiositis de los perros Collie y Shetland pero la distancia obvia entre estas razas hace que el diagnóstico diferencial más probable sca el de lupus eritematoso sistémico. Se consiguieron tratamientos satisfactorios con Dapsona y dosis antiinflamatorias de prednisona. [Parker, W.M., Foster, R.A. Cutaneous vasculitis in five Jack Russell Terriers (Vasculitis cutánea en cinco Terriers Jack Russell). Veterinary Dermatology 1996; 7 : 109–115.] Zusammenfassung— Es wird eine neue, möglicherweise rasseabhängige Vaskulitis bei Jack Russell Terriern beschrieben. Die Veränderungen bestehen in Alopezie, fokalen verkrusteten Geschwüren der distalen Extremitäten und Knochevorsprünge. Histopathologische Veränderungen bestehen in Einezelzellnekrose des Epithels, Pigmentinkontinenz, leukozytoklastischer Vaskulitis und ischämischer Degeneration der Haarfollikel. Dermales ödem und Lymphozyten- und/oder Makrophageninfiltrate werden häufig beobachtet. Klinisch und histopathologisch ähnelt die Erkrankung sehr der Dermatomyositis von Collie und Sheltie, aber die offensichtliche Rassendiskrepanz läßt den systemischen Lupus erythematosus als wahrscheinlichste Differentialdiagnose erscheinen. Dapson und entzündungshemmende Dosen von Prednison zeigten sich als ausreichende Behandlung. [Parker, W. M., Foster, R. A. Cutaneous vasculitis in five Jack Russell Terriers (Kutane Vaskulitis bei fünf Jack Russell Terriern). Veterinary Dermatology 1996; 7 : 109–115.]     

Variation in position of the medial fabella in West Highland white terriers and other dogs

O bjectives : To investigate whether West Highland white terriers exhibit significant variation in the position of the medial fabella compared to both small and large breed dogs.
M ethods : Criteria for the normal location of the medial fabella on a caudocranial radiograph were established. A retrospective analysis was undertaken of a consecutive series of bilateral caudocranial stifle joint radiographs from 70 West Highland white terriers, 100 small and 100 large control dogs by three reviewers. Medial fabellar location, cruciate ligament disease and medial patellar luxation were examined within and between groups.
R esults : Abnormal medial fabellar location was identified in 70 per cent, 9 per cent and 0 per cent of West Highland white terriers, small dogs and large dogs, respectively. In the vast majority of the affected dogs, the fabella was found in a mediodistal location. Presence of concurrent cranial cruciate ligament disease or medial patellar luxation and body weight was excluded as confounding factors.
C linical S ignificance : West Highland white terriers appear predisposed to, and have a high prevalence of, an abnormal mediodistal location of the medial fabella. The authors suggest this is an incidental finding and should not be confused with true pathological fabellar displacement.     

Lack of genetic association among coat colors, progressive retinal atrophy and polycystic kidney disease in Persian cats

An inherited form of progressive retinal atrophy (PRA) is recognized in Persian cats; however, the prevalence of PRA in the breed has not been determined. Breeders suggest that cats from only brown ('chocolate') or Himalayan ('pointed') lines are at risk for PRA, suggesting the disease is not widespread. This study was designed to evaluate whether PRA in Persian cats is associated with three coat colors, including chocolate, or with a highly prevalent inherited disease in this breed--polycystic kidney disease (PKD). Sixty related cats were evaluated for PRA by ophthalmic examination and genetically typed for PKD and the mutations that cause coat color variants in agouti, brown and color (producing the pointed coloration in Himalayan). No associations were identified among any of the traits, including between PRA and chocolate. These data suggest that PRA is not limited to cats with chocolate coat coloration and breeders and veterinarians should be aware that the prevalence of the disease may be higher than currently claimed.     

Deafness prevalence and pigmentation and gender associations in dog breeds at risk

Hearing function was tested in dogs from breeds at risk for pigment-associated congenital sensorineural deafness - Dalmatian, English setter (ES), English cocker spaniel (ECS), bull terrier (BT), Australian cattle dog (ACD), whippet, Catahoula leopard dog, and Jack Russell terrier. Deafness prevalence was highest in Dalmatians and lowest in ECS. Phenotype correlation studies were performed in breeds with >100 brainstem auditory evoked responses (BAER) tested subjects. No gender differences were observed. No differences were seen between black- and liver-spotted Dalmatians, among the ES roan colour varieties, among the ECS parti varieties, or among the ACD colour varieties. Blue eyes were positively associated and patches were negatively associated with deafness in the Dalmatian. Blue eyes were also associated with deafness in the ES and ECS. White BT were more likely than coloured BT to be deaf. Having one or more parent's ear deaf was positively associated with deafness in Dalmatians, ES, and ECS.