Dog sperm head morphometry: its diversity and evolution

Abstract

Dogs have been under strong artificial selection as a consequence of their relationship with man. Differences between breeds are evident that could be reflected in seminal characteristics. The present study was to evaluate differences in sperm head morphometry between seven well-defined breeds of dog: the British Bulldog, Chihuahua, German Shepherd, Labrador Retriever, Spanish Mastiff, Staffordshire Terrier, and Valencian Rat Hunting dog. Semen samples were obtained by masturbation and smears stained with Diff-Quik. Morphometric analysis (CASA-Morph) produced four size and four shape parameters. Length, Ellipticity, and Elongation showed higher differences between breeds. MANOVA revealed differences among all breeds. Considering the whole dataset, principal component analysis (PCA) showed that PC1 was related to head shape and PC2 to size. Procluster analysis showed the British Bulldog to be the most isolated breed, followed by the German Shepherd. The PCA breed by breed showed the Chihuahua, Labrador Retriever, Spanish Mastiff, and Staffordshire Terrier to have PC1 related to shape and PC2 to size, whereas the British Bulldog, Valencia Rat Hunting dog, and German Shepherd had PC1 related to size and PC2 to shape. The dendrogram for cluster groupings and the distance between them showed the British Bulldog to be separated from the rest of the breeds. Future work on dog semen must take into account the large differences in the breeds’ sperm characteristics. The results provide a base for future work on phylogenetic and evolutionary studies of dogs, based on their seminal characteristics.

Dog sperm swimming parameters analysed by computer‐assisted semen analysis of motility reveal major breed differences

“…In particular, associations between sperm head dimensions and swimming parameters have been recorded in birds and mammals (Humphries, Evans, & Simmons, ; Lüpold et al, ; Malo et al, ). In a previous study, we examined dimensions of the sperm head in different dog breeds (Soler et al, ) and a preliminary comparison between them and those of the present study suggest a trend for a positive link with motility, spermatozoa with bigger heads exhibiting higher velocities. This apparent association requires further examination on a larger number of animals and breeds.…”

“…Manual stimulation was used to collect semen samples into sterile sample cups (Soler et al, ). Since a high sperm concentration can have a confounding effect on sperm velocity and linearity (Günzel‐Apel, Günther, Terhaer, & Bader, ; Rijsselaere, Van Soom, Maes, & de Kruif, ), all samples with >50 × 10 6 sperm/ml were diluted with CaniPlus Chill ® sperm extender (Minitub Ibérica S.L., Tarragona Spain) before motility analyses.…”

“…Other studies have suggested associations between body mass and sperm size, so that the bigger the animal the smaller its spermatozoa (Cummins & Woodall, ; Soler, Sancho et al, ). However, this is not observed in the case of dog breeds (Soler et al, ).…”

Puma (Puma concolor) epididymal sperm morphometry

“…It has been observed that mammalian sperm morphometric differences can have an evolutionary significance11 in different species’ diversity (dog,12 rodents,1314 South America camelids15). Similar works could also be done on the Felidae family.…”

Morphometry and subpopulation structure of Holstein bull spermatozoa: variations in ejaculates and cryopreservation straws

“…Since then, multivariate analysis has been introduced for the simultaneous consideration of all the parameters, including their relationships 24. During recent decades, new efforts have been made to define the best analytical approaches by using subpopulation analysis25 and morphological sperm subpopulation structure, based on morphometric data, which has been observed in a great variety of species: dogs,2627 boars,2829 bulls,3031 foxes,32 humans,3334 llamas,15 marmosets,35 pumas,36 rabbits,37 rams,383940 red deer,41 and stallions 42…”