Evaluation of brachycephalic obstructive airway syndrome breeding test results in Finland from 2017 to 2022.

BACKGROUND: Brachycephalic obstructive airway syndrome (BOAS), observed in many flat-faced dog breeds, is one of the most urgent welfare problems in pedigree dogs. Various breeding schemes against BOAS have been implemented in many countries during recent years, but their impact on breed health remains unknown. The BOAS breeding test, used by the Finnish Kennel Club (FKC), includes an exercise component with a recovery assessment, BOAS grading by a veterinarian that evaluates upper respiratory signs before and after exercise, and a nostril stenosis assessment. The aim of our study was to evaluate BOAS breeding test results and estimate the heritability of the BOAS grade using parent-offspring regression from FKC data collected during 2017-2022. RESULTS: The majority (80%) of dogs (n = 957) participating in FKC BOAS testing were English Bulldogs, French Bulldogs, and Pugs. In 2022, 89-100% of the litters from these three breeds registered with the FKC had at least one parent tested for BOAS. The proportion of dogs failing the exercise test was highest in English Bulldogs (11%), followed by French Bulldogs (4%) and Pugs (3%). In these three breeds, moderate to severe BOAS signs were reported in 28%, 22% and 30% of dogs, respectively. The proportion of moderate to severe nostril stenosis was highest (71%) in Pugs, followed by French Bulldogs (55%), and English Bulldogs (40%). Estimates of heritability for BOAS grade were separately calculated for these three breeds and for all dogs, and the estimates were moderate to high, ranging from 0.39 to 0.58. CONCLUSIONS: The exercise test alone did not sufficiently identify dogs with moderate to severe BOAS signs. To better consider the complex nature of BOAS and breed differences, exercise tolerance, the severity of upper respiratory signs (BOAS grade) and nostril stenosis should all be assessed together in breeding animals. The heritability estimates for veterinary-assessed BOAS grade indicated that BOAS grade could be used in selective breeding to obtain less-affected offspring.

Breed differences in social cognition, inhibitory control, and spatial problem-solving ability in the domestic dog (Canis familiaris).

The extraordinary genetic and behavioural diversity of dog breeds provides a unique opportunity for investigating the heritability of cognitive traits, such as problem-solving ability, social cognition, inhibitory control, and memory. Previous studies have mainly investigated cognitive differences between breed groups, and information on individual dog breeds is scarce. As a result, findings are often contradictory and inconsistent. The aim of this study was to provide more clarity on between-breed differences of cognitive traits in dogs. We examined the performance of 13 dog breeds (N = 1002 dogs) in a standardized test battery. Significant breed differences were found for understanding of human communicative gestures, following a human's misleading gesture, spatial problem-solving ability in a V-detour task, inhibitory control in a cylinder test, and persistence and human-directed behaviour during an unsolvable task. Breeds also differed significantly in their behaviour towards an unfamiliar person, activity level, and exploration of a novel environment. No significant differences were identified in tasks measuring memory or logical reasoning. Breed differences thus emerged mainly in tasks measuring social cognition, problem-solving, and inhibitory control. Our results suggest that these traits may have come under diversifying artificial selection in different breeds. These results provide a deeper understanding on breed-specific traits in dogs.

Estimate of heritability and genetic trend of intervertebral disc calcification in Dachshunds in Finland.

BACKGROUND: Intervertebral disc disease (IDD) is a hereditary condition particularly common in Dachshunds. The breed is predisposed to early intervertebral disc degeneration and intervertebral disc calcification (IDC). When calcified, these severely degenerated discs are visible in spinal radiographs. Since the number of calcified discs (NCD) is associated with IDD, spinal radiography can be utilized in screening programmes in attempts to diminish the incidence of IDD in Dachshunds. Our aims were to estimate the heritability and genetic trend of NCD in Dachshunds in Finland and to explore the effect of age at the time of radiographic screening. Since the NCD has a highly skewed distribution, a log-transformed NCD (lnNCD) was also used as an analysed trait. The variance components for both traits were estimated, using the restricted maximum likelihood method. The fixed effects of breed variant, sex, as well as year of screening and the random effects of litter and animal were included in the model. The genetic trends in the NCD and lnNCD were assessed from the estimated breeding values (EBVs) of individual dogs by comparing the mean EBV of dogs born in different years. The breeding values were estimated, using the best linear unbiased prediction animal model. The pedigree in the genetic analyses included a total of 9027 dogs, of which 1567 showed results for NCDs. RESULTS: The heritability estimates of the NCD and lnNCD in Dachshunds were high (0.53 and 0.45, respectively). Small genetic improvements were seen as the mean EBVs increased from 100 to 104 and 105 over a 15-year period. The gain in the entire Dachshund population in Finland may differ from that observed, since less than 10 % of the Dachshunds registered have a screening result for NCD. Age at the time of the screening did not significantly affect the NCD or lnNCD. CONCLUSIONS: We recommend systematic radiographic screening for IDC in Dachshunds and adopting EBVs as a tool for selecting breeding dogs. Age at the time of the radiographic screening may not be as important as previously suggested.