Management of dog sperm parameters and gut microbiota composition with Lactobacillus rhamnosus supplementation

The effects of probiotics supplementation on the reproductive function have been evaluated in many species, but no study has evaluated the changes in the gut microbiome along with the sperm quality changes simultaneously. This study evaluated the effects of dietary supplementation with probiotics on the gut microbiome, sperm quality and gene expression, along with possible correlations between these parameters in dogs. The dogs were supplemented with Lactobacillus rhamnosus for six weeks, and fecal and semen samples were collected at 0, 3, and 6 weeks. Fecal samples were assessed using 16S Metagenomic Sequencing for gut microbiome analysis; and semen samples were analyzed using computer-assisted sperm analysis, DNA and acrosome integrity assessment, viability and morphology assessment, and real-time PCR. The analyses suggested that probiotic supplementation improved kinematic parameters, viability, DNA and acrosome integrity, and morphology of sperms. The mRNA levels of genes associated with fertility, DNA repair and integrity, and antioxidation were also upregulated. The sperm parameters were positively correlated with the relative abundance of Actinobacteria, Allobaculum, Phascolarctobacterium and Catenibacterium, and negatively correlated with Faecalibacterium and Streptococcus. Taken together, the sperm quality enhancement through the gut-testis axis may be due to a change in the gut microorganisms populations.

Lactobacillus acidophilus novel strain, MJCD175, as a potential probiotic for oral health in dogs

The oral cavity is the second-largest habitat for microorganisms, and a well-balanced oral microbiome contributes to preventing dental disorders caused by pathogenic bacteria. Since humans and dogs have different lifestyles and oral microbiome structures, the present study aimed to develop novel probiotics for dogs. A total 53 Lactobacillus spp. were isolated from healthy dogs, and nine isolates were identified as Lactobacillus acidophilus according to 16S rRNA gene sequencing. According to the high antimicrobial activity against the dental caries-causing bacterium Streptococcus mutans, single or three mixed strains were orally administered to dogs for 4 weeks with concentration of 10⁸-10⁹ CFU/day. Intraoral swab samples were collected before and after the administration, and changes of oral pathogen were analyzed using quantitative PCR. Among them, Porphyromonas gingivalis, a critical factor of periodontitis, was significantly reduced in the single-strain administered group. Based on the acid and bile salts tolerance characteristics of isolates, systemic effects were also analyzed by comparing serum immunoglobulin and reproductive ability before and after the administration. However, no significant changes were observed in the serum IgG level and sperm quality. Overall, these in vitro and in vivo results suggest that L. acidophilus isolates from dogs, especially L. acidophilus MJCD175, could be promising probiotic candidates to support oral health without systemic adverse effects in dogs.

Commensal Lactobacilli Enhance Sperm Qualitative Parameters in Dogs

Although several methods have been developed to improve male fertility and sperm quality, subfertility remains a primary clinical issue in male reproduction worldwide. The aim of this study was to determine the effects of the oral administration of three commensal Lactobacillus spp. on healthy normozoospermic dogs and the qualitative parameters of their sperm. Three weeks of supplementation induced a significant decrease of two phyla, Proteobacteria and Tenericutes, and an increase of phylum Firmicutes. At the species level, the number of Fusobacterium perfoetens and Anaerobiospirillum succiniciproducens decreased, while Limosilactobacillus reuteri increased. Parallel to these results, qualitative sperm parameters such as total and progressive motility, acrosome integrity, and other kinematic parameters were significantly enhanced after commensal lactobacilli supplementation. In addition, we showed that Firmicutes were positively correlated with sperm qualitative parameters, while Proteobacteria, F. perfoetens, and A. succiniciproducens were negatively correlated. Considering the similarities between the gut microbiome of dogs and humans, these results provide more insight into how gut microbiota regulation could improve male sperm quality in both species.

Case Report: Orchiopexy in Two Poodle Dogs and Its Effect on Their Sperm Quality Parameters

Cryptorchidism is a common congenital abnormality encountered in veterinary clinics. The treatment of choice for this condition is a surgical procedure named orchiectomy or orchidectomy, where the retained testicle is removed. Surgical placement and fixation of the cryptorchid testicle into the scrotum, referred to as orchiopexy, is used in humans. However, due to the hereditary nature of cryptorchidism in dogs, this treatment option has not been proposed in veterinary clinics. Two adult Poodle dogs were referred to our research facility for a sperm parameter evaluation check. The two dogs were unilateral cryptorchid dogs treated with orchiopexy before the age of 6 months. Their sperm kinematics and morphology were within normal ranges, and their libido and testicles sizes were normal. Treatment of unilateral cryptorchidism by orchiopexy in dogs before the age of 6 months successfully restored spermatogenic function and sperm quality-related parameters. However, due to the nature of this condition, orchiectomy remains the treatment of choice.

Overview on the Antioxidants, Egg Yolk Alternatives, and Mesenchymal Stem Cells and Derivatives Used in Canine Sperm Cryopreservation

Sperm cryopreservation is a widely used assisted reproductive technology for canine species. The long-term storage of dog sperm is effective for the breeding of dogs living far apart, scheduling the time of artificial insemination that suits the female, and preventing diseases of the reproductive tract. However, spermatozoa functions are impaired during the freeze-thaw processes, which may decrease reproductive performance. Numerous attempts have been made to restore such impairments, including the use of cryoprotectants to prevent the damage caused by ice crystal formation, and supplementation of antioxidants to reduce reactive oxygen species generation due to osmotic stress during the procedure. Egg yolk derivatives, antioxidants, and, more recently, mesenchymal stem cells (MSCs) and their derivatives have been proposed in this research field. This review article will summarize the current literature available on the topic.

Leptin Modulates the Metastasis of Canine Inflammatory Mammary Adenocarcinoma Cells Through Downregulation of Lysosomal Protective Protein Cathepsin A (CTSA)

Canine malignant mammary gland tumors present with a poor prognosis due to metastasis to other organs, such as lung and lymph node metastases. Unlike in human studies where obesity has been shown to increase the risk of breast cancer, this has not been well studied in veterinary science. In our preliminary study, we discovered that leptin downregulated cathepsin A, which is responsible for lysosomal-associated membrane protein 2a (LAMP2a) degradation. LAMP2a is a rate-limiting factor in chaperone-mediated autophagy and is highly active in malignant cancers. Therefore, in this study, alterations in metastatic capacity through cathepsin A by leptin, which are secreted at high levels in the blood of obese patients, were investigated. We used a canine inflammatory mammary gland adenocarcinoma (CHMp) cell line cultured with RPMI-1640 and 10% fetal bovine serum. The samples were then subjected to real-time polymerase chain reaction, Western blot, immunocytochemistry, and lysosome isolation to investigate and visualize the metastasis and chaperone-mediated autophagy-related proteins. Results showed that leptin downregulated cathepsin A expression at both transcript and protein levels, whereas LAMP2a, the rate-limiting factor of chaperone-mediated autophagy, was upregulated by inhibition of LAMP2a degradation. Furthermore, leptin promoted LAMP2a multimerization through the lysosomal mTORC2 (mTOR complex 2)/PH domain and leucine rich repeat protein phosphatase 1 (PHLPP1)/AKT1 (Serine/threonine-protein kinase 1) pathway. These findings suggest that targeting leptin receptors can alleviate mammary gland cancer cell metastasis in dogs.

Extracellular Vesicle Mediated Crosstalk Between the Gametes, Conceptus, and Female Reproductive Tract

Extracellular vesicles (EVs) mediated intracellular communication plays an imperative role in the proper completion of different physiological events. Most of the bio-fluids are enriched with several subpopulations of EVs including exosomes and microvesicles (MVs), with the capacity of transferring different functional molecules (lipids, proteins, and nucleic acids) to target cells. Recipient cells upon receiving the signal molecules undergo different changes that positively affect the structural and functional integrity of the cells. This article was aimed to highlight the role of EVs secreted by gametes, the female reproductive tract, and the growing conceptus in the successful completion of different reproductive events related to gestation. EVs associated with the reproductive system are actively involved in the regulation of different physiological events including gamete maturation, fertilization, and embryo and fetal development. In the reproductive system, EVs mediated intracellular communication is not unidirectional but is rather regulated through crosstalk between the reproductive tract and the growing conceptus. These vesicles are secreted from the ovary, oviductal epithelium, endometrium, developing embryo, and the placenta. The cargo inside these vesicles exerts pleiotropic effects on both maternal and embryonic environments. A better understanding of the EVs-mediated crosstalk will be helpful in the development of useful tools serving both the diagnostic as well as therapeutic needs related to female fertility.