Pedigree structure, inbreeding, and survival analysis in an Irish Wolfhound cohort

The Irish Wolfhound (IW) is a giant dog breed characterized by a relatively short lifespan, a high prevalence of heritable disorders, and extensive relatedness among lineages. Despite the recognized importance of inbreeding and population structure in purebred dogs, relatively little is known about how pedigree structure and demographic parameters influence survival patterns in large multinational IW populations. The aim of this study was to investigate pedigree structure, inbreeding, demographic parameters, and survival patterns in a multinational cohort of Irish Wolfhounds. An integrated pedigree comprising 2,343 individuals was reconstructed from the five-generation pedigrees of 96 reference dogs previously included in a genomic study. Pedigree completeness, ancestor redundancy, parental contribution, genealogical recurrence, generation interval, inbreeding coefficients, and effective population size (Ne) were evaluated. Longevity and survival analyses were performed using Kaplan-Meier estimators and Cox proportional hazards models.

Within the reconstructed pedigree, analyses revealed heterogeneous genealogical depth and substantial pedigree interconnectedness. The pedigree-based Ne estimate was 90.1 and remained similar (85.9) when a more restrictive pedigree-depth criterion was applied. Most recorded deaths occurred between 6 and 10 years of age. Females showed significantly lower mortality risk and slightly greater longevity compared with males; no significant cohort effects were detected. After adjustment for pedigree depth, pedigree-based inbreeding coefficients were not significantly associated with survival. Individuals with limited ancestral information often showed low or zero inbreeding coefficients despite reduced survival estimates, suggesting that missing pedigree data may underestimate relatedness and autozygosity.

Overall, the results highlight the importance of pedigree completeness for accurate interpretation of inbreeding and survival analyses in highly interconnected populations. Integrating pedigree and genomic information may improve the assessment of population structure and health dynamics in purebred dogs.