Evaluation of the present breeding programme against copper toxicosis in Danish Bedlington terriers

Artificial Selection Drives SNPs of Olfactory Receptor Genes into Different Working Traits in Labrador Retrievers

Labs as guide dogs or sniffer dogs in usage have been introduced into China for more than 20 years. These two types of working dogs own blunt or acute olfactory senses, which have been obtained by artificial selection in relatively closed populations. In order to attain stable olfactory attributes and meet use-oriented demands, Chinese breeders keep doing the same artificial selection. Though olfactory behavior is canine genetic behavior, genotypes of OR genes formed by breeding schemes are largely unknown. Here, we characterized 26 SNPs, 2 deletions, and 2 insertions of 7 OR genes between sniffer dogs and guide dogs in order to find out the candidate alleles associated with working specific traits. The results showed that there were candidate functional SNP alleles in one locus that had statistically severely significant differences between the two subpopulations. Furthermore, the levels of polymorphism were not high in all loci and linkage disequilibrium only happened within one OR gene. Hardy–Weinberg equilibrium (HWE) tests showed that there was a higher ratio not in HWE and lower FST within the two working dog populations. We conclude that artificial selection in working capacities has acted on SNP alleles of OR genes in a dog breed and driven the evolution in compliance with people's intentions though the changes are limited in decades of strategic breeding.

NHLRC1 repeat expansion in two beagles with Lafora disease

Lafora disease is a fatal genetic disorder characterised by neurotoxic deposits of malformed insoluble glycogen. In humans it is caused by mutation in the EPM2A or NHLRC1 genes. There is a known mutation in miniature wirehaired dachshunds which has not been documented in other dog breeds, including beagles, in which the disease is relatively commonly reported. This case report describes the causative defect in two affected beagles, namely the same massive expansion as in miniature wirehaired dachshunds of a 12-nucleotide repeat sequence that is unique to the canine NHLRC1 gene. This is the first mutation described in beagles with Lafora disease, and so far the only Lafora disease genetic variant in dogs.

Identification of a mutation in the CHAT gene of Old Danish Pointing Dogs affected with congenital myasthenic syndrome

The presence of a recessive inherited muscle disease in Old Danish Pointing Dogs has been well known for years. Comparisons of this disease with myasthenic diseases of other dog breeds and humans have pointed toward a defect in the synthesis of the neurotransmitter acetylcholine possibly due to decreased activity of the enzyme choline acetyltransferase. We sequenced exons 5-18 of the gene encoding choline acetyltransferase (CHAT) in 2 affected and 2 unaffected dogs and identified a G to A missense mutation in exon 6. The mutation causes a valine to methionine substitution and segregates in agreement with the inheritance of the disease. The mutation was not detected in 50 dogs representing 25 other dog breeds. A DNA test has been developed and is now available to the breeders of Old Danish Pointing Dogs.

Genetic counseling in the era of molecular diagnostics

Veterinarians with an interest in theriogenology will often be asked by small animal clients for advice concerning hereditary diseases in their breeds. Many new DNA-based tests for analysis of genetic diseases and traits (e.g. coat color) are now available for use by both breeders and veterinarians. With appropriate interpretation, these tests can be invaluable tools in a breeding program. For example, they can be used to produce animals free of specific diseases, to quickly eliminate a disease from an entire breed, or to select for specific traits in breeding stock. Selection strategies that do not take into account maintaining genetic diversity of the breed may be detrimental and reduce the potential for future improvement.

Microsatellite marker analysis of the genetic variability in Hanoverian Hounds

Genetic variability of the dog breed Hanoverian Hound was analysed using a set of 16 microsatellites. The sample of 92 dogs was representative for the total current population [n=334, inbreeding coefficient 9.2%, relationship coefficient 11.2%] with respect to the level and distribution of the inbreeding and relationship coefficients. All microsatellites used were in Hardy-Weinberg equilibrium. The average number of alleles was 6.4. The average observed heterozygosity (H(O)) was slightly higher than the expected heterozygosity (H(E)). Dinucleotide microsatellites exhibited lower polymorphism information content (PIC) than tetranucleotide microsatellites (0.52 versus 0.66). The average PIC was 0.61. The individual inbreeding coefficient was negatively related to the average H(O) of all microsatellites, whereas the proportion of genes from introducing of Hanoverian Hounds from abroad showed no relationships to H(O). We found that the genetic variability in the Hanoverian Hounds analysed here was unexpectedly higher than that previously published for dog breeds of similar population size. Even in dog breeds of larger population size heterogyzosity was seldom higher than that observed here. The rather high genetic variability as quantified by polymorphic microsatellites in Hanoverian Hounds may be due to a large genetic variation in the founder animals of this breed and to the fact that this genetic diversity could be maintained despite genetic bottlenecks experienced by this breed in the 1920s and 1950s and despite the presence of high inbreeding and relationship coefficients for more than 50 years.

Genetic variability of seven dog breeds based on microsatellite markers

The present study, compared the genetic variability of seven dog breeds and a test sample from Switzerland by means of 26 microsatellite markers. Five loci were excluded from further analyses because one was monomorphic, one not in Hardy-Weinberg equilibrium in all breeds and three in linkage disequilibrium with linked loci. The proportion of shared alleles at the individual level of the remaining 21 microsatellite markers combined with the neighbour-joining method allowed for the clustering of the large majority of the individuals in accordance to their breed. The results were confirmed by analyses using a Bayesian approach for clustering and a Monte Carlo re-sampling method for individual assignment or exclusion to a given population.