Risk factors associated with the infection of sheep with Dichelobacter nodosus.

Ovine footrot is a highly contagious foot disease caused by the gram-negative bacterium Dichelobacter nodosus (D. nodosus). In a recent report, we showed a prevalence of 42.9% D. nodosus positive swabs across Germany. In this follow-up study, we used real-time PCR results for D. nodosus and footrot scores of 9297 sheep from 208 flocks and collated these data with survey data on herd and animal characteristics and herd management. The aims of the present study were to investigate herd and animal factors associated with D. nodosus infection and footrot scores in individual sheep. Multivariable analyses with generalized mixed models showed that month of recording, breed, herdbook membership, use of antibiotics, and footbaths in the past 3-10 years, signs of footrot in the past 12 months and flock environment of the sheep, modelled as a random farm effect within region, were significant risk factors. Among the 21 different breeds, Romney had the lowest risk of D. nodosus infection, while Swifter had the highest risk and German Merino and German White Heath were the next breeds at highest risk of D. nodosus infection. The variance between farms in the prevalence of D. nodosus was large and accounted for 84% of the total variance in the mixed model analysis. We conclude that specific and as yet unknown effects influencing D. nodosus infections in flocks, as well as breed and weather, are the most important effects on D. nodosus infection in sheep, pointing towards the need to establish adequate infection control at farm level.

Prevalence of Dichelobacter nodosus and Ovine Footrot in German Sheep Flocks.

The bacterium Dichelobacter nodosus (D. nodosus) is the causative agent of ovine footrot. The aim of this field study was to determine the prevalence of D. nodosus in German sheep flocks. The sheep owners participated voluntarily in the study. More than 9000 sheep from 207 flocks were screened for footrot scores using a Footrot Scoring System from 0 to 5 and sampling each sheep using one interdigital swab for all four feet of the sheep. The detection and discrimination between benign and virulent strains was done employing a real-time PCR. Our results showed a mean prevalence of 42.93% of D. nodosus in German sheep on an animal level. Underrunning of hoof horn on at least one foot (Scores 3-5) was detected in 567 sheep (6.13%). Sheep with four clinically healthy feet were found through visual inspection in 47.85% of all animals included in this study. In total, 1117 swabs from sheep with four clinically healthy feet tested positive for D. nodosus. In 90.35% of the positive swabs, virulent D. nodosus were detected. Benign D. nodosus were detected in 4.74% of the D. nodosus-positive swabs while 4.91% tested positive for both, benign and virulent D. nodosus. In 59 flocks D. nodosus were not detected and in 115 flocks only virulent D. nodosus were found while seven flocks tested positive for benign strains.

Demographic assessment of the Dalmatian dog - effective population size, linkage disequilibrium and inbreeding coefficients.

BACKGROUND: The calculation of demographic measures is a useful tool for evaluating the genomic architecture of dog breeds and enables ranking dog breeds in terms of genetic diversity. To achieve this for the German Dalmatian dog population, 307 purebred animals of this breed were genotyped on the Illumina Canine high density BeadChip. The analysis of pedigree-based inbreeding was performed based on a pedigree with 25,761 dogs including the genotyped dogs. RESULTS: The effective population size derived from squared correlation coefficients between SNP alleles (r 2) was 69. The maximum value of r 2 was 0.56, resulting in a 50% decay value of 0.28 at a marker distance of 37.5 kb. The effective population size calculated from pedigree data using individual increase in inbreeding over equivalent generations was 116. The pedigree inbreeding coefficient was 0.026. The genomic inbreeding coefficient based on the length of runs of homozygosity (ROH) was calculated for seven length categories of ROHs, and ranged from 0.08 to 0.28. The fixation coefficients FIS_PED and FIS_GENO were at 0.017 and 0.004. PANTHER statistical overrepresentation analysis of genes located in consensus ROHs revealed highly underrepresented biological processes in 50% of the investigated dogs. One of those is the 0.28 fold enriched "immune response", which might be associated to the high prevalence of allergic dermatitis in the breed. Candidate genes for congenital sensorineural deafness (CCSD, a highly prevalent disease in the Dalmatian) were discovered in consensus ROHs. CONCLUSIONS: The fast decay of r 2 and the moderate inbreeding coefficients indicate that the German Dalmatian dog population is rather diverse. Pedigree- and genomic-based inbreeding measures were highly correlated and therefore prove good reliability for the given population. Analyses of consensus ROHs with genes coding for deafness and other breed-defining traits, such as hyperuricosuria, indicate that those ROH became fixed in the Dalmatian population about 500 years ago. In case of the Dalmatian dog, a ROH of 40 SNPs length is enough to investigate signatures of selection (e.g. the ROH with the fixed hyperuricosuria mutation) as far back as the breed formation point approximately 500 years ago.

A de Novo EDA-Variant in a Litter of Shorthaired Standard Dachshunds with X-Linked Hypohidrotic Ectodermal Dysplasia.

In this study, we present a detailed phenotype description and genetic elucidation of the first case of X-linked hypohidrotic ectodermal dysplasia in the shorthaired standard Dachshund. This condition is characterized by partial congenital hypotrichosis, missing and malformed teeth and a lack of eccrine sweat glands. Clinical signs including dental radiographs and histopathological findings were consistent with ectodermal dysplasia. Pedigree analysis supported an X-recessive mode of inheritance. Whole-genome sequencing of one affected puppy and his dam identified a 1-basepair deletion within the ectodysplasin-A (EDA) gene (CM000039.3:g.54509504delT, c.458delT). Sanger sequencing of further family members confirmed the EDA:c.458delT-variant. Validation in all available family members, 37 unrelated shorthaired standard Dachshunds, 128 further Dachshunds from all other coat and size varieties and samples from 34 dog breeds revealed the EDA:c.458delT-variant to be private for this family. Two heterozygous females showed very mild congenital hypotrichosis but normal dentition. Since the dam is demonstrably the only heterozygous animal in the ancestry of the affected animals, we assume that the EDA:c.458delT-variant arose in the germline of the granddam or in an early embryonic stage of the dam. In conclusion, we detected a very recent de-novo EDA mutation causing X-linked hypohidrotic ectodermal dysplasia in the shorthaired standard Dachshund.