Reproductive parameters in Yorkshire terrier dogs in Poland

Abstract

The aim of this study was to determine the basic reproductive parameters, i.e., litter size, gestation length, neonatal mortality rate and the type of delivery in Yorkshire terrier dogs, one of the most popular breeds in Poland. We have verified a hypothesis put forward by breeders that larger females have fewer whelping difficulties and produce larger litters and that pregnancies of females having one or two pups last longer. The focus of investigation was reproductive data from 66 Yorkshire terrier females registered in the Lublin Branch of the Polish Kennel Club, an FCI (Federation Cynologique Internationale) member, which whelped 124 litters comprising in total 508 pups from 37 fathers. The data were collected between August 2009 and December 2014. The significance of differences was verified using Mann-Whitney U and Kruskal-Wallis H-tests. The relationships between the recorded dogs’ reproduction traits were estimated by calculation of Spearman’s correlation coefficients with the use of the statistical programmes Statistica and SPSS 20. The investigations have confirmed the hypothesis concerning the larger litter size produced by larger females and the lower incidence of postpartum dystocia; however, the hypothesis of the impact of body weight on the length of pregnancy was rejected. The differences between the body weights of stud females and males reached 125%. The Yorkshire terrier appears to be a good reproductive breed with normal reproductive functions and good reproductive parameters.