Investigating the relationship between inbreeding and life expectancy in dogs: mongrels live longer than pure breeds.

This study aimed to investigate the establishment of relationship between inbreeding and life expectancy in dogs. A dataset of N = 30,563 dogs sourced from the VetCompass™ Program, UK was made available by the Royal Veterinary College, University of London, containing information about breed and longevity and was subject to survival analysis. A Cox regression proportional hazards model was used to differentiate survivability in three groups of dogs (mongrel, cross-bred and pure breed). The model was found highly significant (p < 0.001) and we found that mongrel dog had the highest life expectancy, followed by cross-bred dogs with only one purebred ancestor and purebred dogs had the lowest life expectancy. A second Cox regression was also found highly significant (p < 0.001) differentiating the lifespan of different dog breed and correlating positively the hazard ratio and the Genetic Illness Severity Index for Dogs (GISID). The results show that survivability is higher in mongrel dogs followed by cross-bred with one of the ancestor only as a pure breed, and pure breed dog have the highest morbidity level. Higher morbidity is associated with higher GISID scores, and therefore, higher inbreeding coefficients. These findings have important implications for dog breeders, owners, and animal welfare organizations seeking to promote healthier, longer-lived dogs.

A meta-analysis of the mastitis vaccination efficacy in dairy cattle.

Background: Mastitis is the most important disease in dairy cattle with impact in welfare of animals and the economy of the dairy farming activity. Attempts have been made to produce vaccines to prevent the disease, however, results have been dubious. Aim: The aim of this study was to evaluate the efficacy of the mastitis vaccination in dairy cattle by merging several trials to allow evidence synthesis. Methods: A list of publications with common methodological grounds was selected to allow a quantitative comparison in a meta-analysis with moderators. Results: A mixed methods model (p < 0.001), with four significant moderators was successfully fitted: "year of publication" (p < 0.001), "vaccination timing" (p < 0.01), "type of animal" (p < 0.001), and "vaccine fabrication" (p < 0.001). The model is homogeneous (p > 0.05), with the moderators explaining the variability. Efficacy decreases over time. Vaccines applied after calving show inefficacy [log risk ratio (RR) 1.72 (1.34, 2.21)], and applied before calving show reduced efficacy [log RR 0.86 (0.72, 1.03)]. Commercial vaccines don't show efficacy [log RR 1.07 (0.94, 1.22)]. Self-fabricated vaccines show efficacy [log RR (0.51, 0.94)]. Conclusion: Full clarification of efficacy is not shown; however, if vaccination is used, must follow a pre-calving protocol. While not showing efficacy, the vaccination has demonstrated a reduction of the severity in clinical cases, rate of culling, and has increased the production of milk and milk solids. Vaccination may improve health and welfare but does not prevent the disease effectively; it must be seen as an additional tool to the traditional preventive measures.