Sexual dimorphism of Labrador Retriever dogs by morphometry

Abstract

The domestic dog (Canis familiaris) is the species of greatest morphological diversity among mammals. Seventy-four Labrador Retriever dogs- 27 males and 47 females - were used in this experiment. Thirty quantitative biometric characteristics, related to morphology were measured. The objective of this study was to evaluate the morphometric traits of the Labrador Retriever breed to establish descriptive biometric attributes that may show sexual dimorphism through principal component analysis (PCA) and discriminant analysis (DA). The PCA was processed using all the variables and performing a pre-selection of the most correlated variables. The DA was performed for the 30 variables and also for the five most correlated variables with the first component (CP1), in order to classify new individuals. The PCA was able to identify sexual dimorphism in size, with both the 30 original variables as with the pre- selected variables, the latter optimized the reduction to two principal components. The DA was able to discriminate the two populations, both for 30 variables as for the five variables most correlated with the CP1. The functions with five variables can be used to classify other purebred dogs for sex, with an error of about 6.75%.