Effect of drugs on fertility in male dogs: A review

The reproductive microbiome in dogs: Friend or foe?

The microbiome of the reproductive tract is an area of research in full development. Specifically, the microbiome may be involved in reproductive health, disease, and pregnancy outcomes, as has been shown in humans and animals, including dogs. The aim of the present review was to summarize current knowledge on the microbiome of the canine reproductive tract, to expose the controversial role that some bacterial agents may play in canine subfertility, and to highlight future research perspectives. This review discussed whether the use of antimicrobials in dogs is appropriate to increase reproductive performance and to treat subfertility without proper diagnosis, and the possible use of probiotics to modulate the reproductive canine microbiome. Finally, we indicate areas in which scientific knowledge is currently lacking, and could be promising directions for future research.

Characterization of the semen microbiota of healthy stud dogs using 16S RNA sequencing

The reproductive microbiota of male dogs has never been investigated using culture-independent sequencing techniques. The purpose of the present study was to get seminal knowledge on the microbiota of the ejaculate. Specifically, factors as the fraction of the ejaculate, the sperm quality (normospermia, teratozoospermia), and the living environment were evaluated. The sperm-rich and the prostatic fractions of the ejaculate were collected from healthy stud dogs. Following the sperm analysis, samples from twenty animals (normospermic n = 10 and teratozoospermic n = 10) were stored at - 80 °C until further processing including DNA extraction and 16S rRNA sequencing. Alpha- (Shannon index) and beta- (Bray-Curtis, Unweighted UniFrac) diversities were assessed and compared (PERMANOVA) based on the group of samples (biological samples from the ejaculate and controls), the fraction of the ejaculate (sperm-rich and prostatic fractions), the animal group (normospermia and teratozoospermia), and the living environment of the animal (kennel or pet living in-house). The most abundant bacterial phyla in canine semen samples were Proteobacteria, Firmicutes, and Actinobacteria. Overall, the dominant bacterial family was that of Pasteurellaceae The genus Mycoplasma was never detected. No differences in terms of bacterial composition were found based on the fraction of the ejaculate and based on the animal group (P > 0.05). On the other hand, differences in alpha and beta diversities were highlighted based on the living environment (P = 0.001). Overall, the results of the present study provide preliminary insights on dog semen microbiota, opening a new chapter in the field of canine andrology. Our results suggest that the environment may play a role in influencing the reproductive microbiota of male dogs and that the prostatic fraction of the ejaculate can be used for further research as a representative of the semen microbiota.

Influence of dietary supplementation with Lepidium meyenii (Maca) on sperm quality in dogs

Maca is a traditional Andean crop used as a nutraceutical for the fertility-enhancing properties that are linked with antioxidant activity. The aim of this study was to evaluate, for the first time, the potential beneficial effects of oral Maca (Lepidium meyenii or Lepidium peruvianum) supplementation in improving reproductive performance in male dogs. Forty-eight male dogs of different breeds were enrolled in the study, fed the same maintenance diet, and exposed to the same environmental conditions. The subjects were divided into four groups of 12 dogs each: Subfertile treatment group, Subfertile control group, Normofertile treatment group, and Normofertile control group. The dogs in the treatment groups received Lepidium meyenii in their diet in a capsule formulation [75 mg/kg Maca extract 10:1, thickening agent (hydroxypropyl methylcellulose), ground rice], while the control groups received placebo capsule (starch). For each subject included in the study, the spermiogram was analyzed at three time points of the sperm cycle: at day 0 (T0), day 31 (T31), and day 62 (T62). Dietary supplementation with Maca in subfertile subjects resulted in a significant increase in ejaculate volume and total sperm count compared to the control group. This increase was also observed in normofertile subjects in the treatment group. In addition, total and progressive motility as well as sperm morphology were significantly improved in the groups treated with Maca compared to the control groups. The results thus highlight, for the first time, the potential efficacy of supplementation with 75 mg/kg of Maca extract daily in improving semen quality in dogs.