genetic diseases in chihuahuas

2009;12:25362. Correspondence to TB collected and collated the data, assisted in analysis, and aided interpretation of the data. Similarly, the inability to determine risk for individual breeds reflects insufficient representation of every individual breed thereby preventing meaningful analyses of the contribution of individual breeds to genetic risk of a particular disorder. That study also compared prevalence of these common conditions between purebred and mixed-breed dogs and showed that purebred dogs had significantly higher prevalence only for otitis externa, obesity, and skin mass lesion. Evolutionary genomics of dog domestication. Other disorders, such as atopy/allergic dermatitis, hypothyroidism, and IVDD, were more pervasive across the purebred population (Tables2 and 3). A review by Wade [36] may provide insight into these seemingly contradictory findings. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. Illinois State Museum Landscape History Program 2014. Part of Hulley SB, Cummings SR, Browner WS, Grady DG, Newman TB. Canine Genetics and Epidemiology 1963;65:42930. PLoS ONE. CAS Trevejo R, Yang M, Lund EM. Shearin AL, Ostrander EA. Google Scholar. J Am Anim Hosp Assoc. The number of mixed-breed dogs used in the analyses was 22,683. Disorders that were found to be more prevalent among subsets of the purebred population may be due to liability genes passed down from founding ancestors of related breeds, a consequence of selecting for a structural morphology that predisposes certain disorders, or the interplay between ancestral mutations and a morphological phenotype. This would suggest that most breeds comprising the herding group are not at higher risk for aortic stenosis but the German shepherd is more prone which is consistent with the literature [1618]. Google Scholar. 2005;66:17384. The domestic dog is frequently cited as being an exceptional model for human inherited disorders due to the number of diseases identified, similarity in disease presentation, and population structure in the dog [1]. Notably though, the overall prevalence within the mixed-breed population exceeded 4 % possibly reflecting the breeds at risk to IVDD contributing to the ancestry of a mixed-breed dog. For each comparison, the purebred subgroups to mixed-breed odds ratio was determined as was the mean P value used to test this ratio. To enhance reliability of the analyses, sampling of matched healthy to affected dogs was repeated 50 times. By using this website, you agree to our Using published genomic data, actual genetic diversity was compared to estimates derived from pedigree analyses; the pedigree analyses tended to underestimate the extent of genetic diversity [36]. Herding and hound groups showed higher probabilities for four, non-sporting in five, working in six, and sporting in seven disorders as compared to the mixed-breed population. Individual dogs may have equivalent weight but have significantly different morphologies. In contrast, for aortic stenosis, gastric dilation volvulus, early onset cataracts, dilated cardiomyopathy, elbow dysplasia, epilepsy, and portosystemic shunt, the prevalence in most purebred groups was not distinct from that seen in the mixed-breed population. For other disorders, although the study was designed to account for potential influences of weight on prevalence of disorders by comparing purebreds to mixed-breeds that were matched for weight, some disorders may reflect structural differences. Furthermore, various dog breeds retain approximately 87 % of the genomic diversity seen in the ancestral wolf [36] suggesting sufficient genetic diversity exists within breeds provided breeders do not homogenize the breeds. 2013;197:3517. Because not all purebred breeds are designated into the AKC breed groupings, the number of dogs used in the analyses was 88,635. O'Grady MR, Holmberg DL, Miller CW, Cockshutt JR. Canine congenital aortic stenosis: a review of the literature and commentary. The authors declare that they have no competing interests. Population structure and inbreeding from pedigree analysis of purebred dogs. Specifically, dogs were classified as controls if none of the inherited conditions under study were diagnosed. Cite this article. Furthermore prevalence was highly breed dependent, leading the authors to suggest that any breeding reforms with a goal to improve the health of dogs must consider conditions amenable to genetic improvement and do so on a breed-by breed basis. Thus, perhaps it is time to consider that all health conditions have some degree of inheritance and assessing lineage contributions may play a role in reducing incidence within all disorders. Golden retrievers, Labrador retrievers, German shepherds, Bernese mountain dogs, and Rottweilers are all known to be predisposed to elbow dysplasia [22]. All authors read and approved the final manuscript. Lund E. Epidemiology of canine atopic dermatitis. Tidholm A. Retrospective study of congenital heart defects in 151 dogs. PubMed Central However, the Bernese mountain dog, the Newfoundland, and the Rottweiler breeds, having the highest prevalence for elbow dysplasia in this data set [6], are classified as retrievers by haplotype allele sharing. Briefly, dogs were classified as having one of the 24 inherited disorders studied (hemangiosarcoma, lymphoma, mast cell tumor, osteosarcoma, aortic stenosis, dilated cardiomyopathy, hypertrophic cardiomyopathy, mitral valve dysplasia, patent ductus arteriosus, ventricular septal defect, hyperadrenocorticism, hypoadrenocorticism, hypothyroidism, elbow joint dysplasia, hip joint dysplasia, IVDD, patellar luxation, ruptured anterior cranial cruciate ligament, atopy or allergic dermatitis, GDV, cataracts in dogs 6 years or younger, epilepsy, lens luxation, and portosystemic liver shunt) only if the record included definitive confirmation of the condition by the veterinary medical teaching hospital staff or the referring veterinarian. Jansson M, Laikre L. Recent breeding history of dog breeds in Sweden: modest rates of inbreeding, extensive loss of genetic diversity and lack of correlation between inbreeding and health. The ability to record health data for defined breeds has simultaneously permitted genetic dissection of particular disorders and bolstered the implicit assumption that purebred dogs are more prone to inherited disorders than mixed-breed dogs [25]. Manage cookies/Do not sell my data we use in the preference centre. One study reported that higher levels of inbreeding and reduced genetic diversity were associated with a reduction in the prevalence of hip dysplasia [32]. This suggests that the breed contributing to the increased risk in the AKC herding group is the German shepherd dog, a breed having an elbow dysplasia prevalence of ~19 % (www.offa.org/stats_ed.html, accessed 07/14/2014). AMO designed the study, assisted in analysis, and drafted the manuscript. Nat Rev Genet. Mixed-breed dogs numbered 22,683. Studies that have comprehensively assessed the genetic diversity of particular dog breeds have uncovered contradictions to the assumption that loss of diversity and inbreeding correlates with reduced health. Dogs were stratified by weight, age, sex, and breed category (AKC breed category or shared haplotype category) as previously described [6]. For each disorder evaluated, the sampled data set was used to estimate the proportion of each purebred breed category with the disorder relative to the proportion of mixed-breed dogs with the disorder. Tissue Antigens. Calboli FC, Sampson J, Fretwell N, Balding DJ. Data presented as mean OR (with 95 % CI) of the purebred group relative to mixed-breed dogs, mean P value of the matched control sampling sets, and the number of times (of 50) that those matched control sampling sets indicated a significant difference in probability that mixed-breed and purebred categories differed in prevalence of each condition (denoted in italics), Red upward arrows indicate a significant increased risk of presentation whereas green downward arrows indicate a reduced risk of the condition relative to mixed-breed dogs. CAS California Privacy Statement, Although the resolution of the diagnosis of elbow dysplasia in the present study does not allow attribution of individual conditions to breeds as done by LaFond et al. An additional limitation is that for some groupings, a condition may be rare or the number of dogs classified in a particular group was not frequently seen at the teaching hospital leading to imprecise risk estimates. Similarly, atopy/allergic dermatitis is found in greater prevalence in some breeds [11, 12] whereas other purebred dog breeds had equivalent prevalence to mixed-breed dogs [13]. Purebred dogs of AKC breeds were categorized into one of the seven AKC breed group designations (n = 65,952): herding (n = 9724), hound (n = 5344), non-sporting (n = 6516), sporting (n = 18,940), terrier (n = 4885), toy (n = 9798), and working (n = 10,745) (Additional file 1: Table S1). 2013;242:154955. Vet Record. Accordingly, any post-hoc adjustment of P values (e.g., Bonferroni adjustment) was unnecessary. For each condition, the random sampling from the control dogs was repeated [6]. Analysis of 88,635 dogs seen at the University of California, Davis Veterinary Medical Teaching Hospital from 1995 to 2010 identified ten inherited conditions having greater prevalence within the purebred dog population as compared to the mixed-breed dog population: aortic stenosis, atopy/allergic dermatitis, gastric dilatation volvulus (GDV), early onset cataracts, dilated cardiomyopathy, elbow dysplasia, epilepsy, hypothyroidism, intervertebral disk disease (IVDD), and hepatic portosystemic shunt. Disorder by breed groupings: Defining the lineage associations for particular disorders may provide approaches to both breeding strategies and therapeutic interventions. PubMed Central Veterinary J. 2013;196:927. 2001;21:323. Open J Veterinary Med. Breeds categorized by AKC breed group and by haplotype allele sharing as per Wayne and VonHoldt [1].). Canine Genet Epidemiol 2, 9 (2015). 2011;238:898904. J Am Vet Med Assoc. The predisposition of these breeds for the inherited disorder further supports the common ancestry of the disorder shown by the association with breeds sharing alleles although environmental factors such as diet or exercise or enhanced screening by owners for these breeds also contribute to the prevalence reported. Excessive odds ratio (OR) values should be interpreted with caution because though increased risk may exist, the magnitude of that risk may be lower than the value computed. Some disorders appear linked to common ancestors providing insight into disease allele origin whereas others may be due to selection for common structural morphology. LaFond E, Breur GJ, Austin CC. A preference for a particular morphology designated by a breed standard may contribute to a greater prevalence for purebreds, as in the case for IVDD. Disorders that require more extensive diagnostic procedures may also inflate the risk determined because motivation to fully diagnose a condition may differ between owners of purebred and mixed-breed dog owners. 2014;9:90501. The present study illustrated that certain subpopulations of the purebred dog population were more likely to display certain conditions while other subpopulations were not statistically different than mixed-breed dogs in terms of disease prevalence. PubMed Central CAS Comhaire FH. Terms and Conditions, The present study identified specific breed groupings that contributed to disorders being more frequently observed in the purebred dog population. Brockman D, Washabau R, Drobatz K. Canine gastric dilatation/volvulus syndrome in a veterinary critical care unit: 295 cases (19861992). statement and 2006;159:2416. When considering the genomic similarities of the breeds based on haplotype sharing, ancient and spitz, herding, and sight hounds showed greater probability for one of the disorders when compared to mixed-breed dogs whereas scent hound, small terrier, and toy breeds showed higher probability in two, mastiff-like, working group 1, and spaniel in four, and retrievers and working group 2 for six of the inherited disorders. The number of purebreds able to be categorized into the AKC breed groupings and used in the analyses was 65,952 while the number of purebreds categorized based upon allele sharing was 55,353. Briefly, a logit link function with the model terms including the class variables of age, weight, sex and breed group was applied to the binomial disorder status. Reports in the literature show that breeds defined by haplotype to be retrievers (Newfoundlands) and mastiff-like (boxers and the Dogue de Bordeaux) have a genetic predisposition for aortic stenosis [1921] also corroborating the current findings. This concept is supported by the observation that the terrier group had lower risk when compared to the mixed-breed population. In comparing the purebred dog population to the mixed-breed dog population for ten inherited conditions found at a higher frequency in purebred dogs, the current data indicate that risk for certain inherited disorders can be apportioned to specific purebred populations. PubMed The results offer an assessment of the distribution of inherited disorders within purebred dogs and illustrate how mixed-breed and subpopulations of purebred dogs do not differ statistically in prevalence for certain disorders. Hospital controls from the same patient population were used in accordance with clinical research designs [40]. 2014;121. Inheritance of hypoadrenocorticism in bearded collies. Breed susceptibility for developmental orthopedic diseases in dogs. This study represents a further analysis of the database interrogated in the report by Bellumori et al., [6] in which the prevalence of inherited conditions were compared between purebred and mixed-breed dog populations seen at a veterinary teaching hospital over a 15-year period. Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. J Anim Sci. Our analysis sought to describe the distribution of inherited disorders as a function of purebred categories when compared to the mixed-breed population for those ten inherited conditions determined to be more prevalent in the purebred population as a whole. Farrow T, Keown A, Farnworth M. An exploration of attitudes towards pedigree dogs and their disorders as expressed by a sample of companion animal veterinarians in New Zealand. Voith VL, Ingram E, Mitsouras K, Irizarry K. Comparison of adoption agency breed identification and DNA breed identification of dogs. The relationship of inherited disorders and breed groupings in the present study supports the role of common ancestry to the contribution of risk. Genetic evidence of subaortic stenosis in the Newfoundland dog. These seven conditions showed higher risk only for certain subgroups of the purebred dog population. Observed in the present study supports the role of common ancestry to the mixed-breed population the study, in! Correspondence to TB collected and collated the data, assisted in analysis, and interpretation!, dogs were classified as controls if none of the analyses, sampling of matched to! [ 40 ]. ) R, Drobatz K. Canine gastric dilatation/volvulus syndrome in a veterinary critical care:. 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