Update on Seminal Vesiculitis in Stallions

Seminal vesiculitis in stallions reduces fertility and is often underdiagnosed. The most common cause is infection of seminal vesicles by bacteria capable of forming biofilms and a propensity for tissue persistence, for example, Pseudomonas aeruginosa. Achieving a clinical cure is challenging because of a high rate of recurrence. Systemic antibiotic therapy does not reach adequate therapeutic concentrations within the seminal vesicles; one alternative is endoscopy-guided, local antibiotic infusion into the gland lumen, with or without concurrent systemic antibiotics. Current diagnostic and therapeutic strategies for seminal vesiculitis are less than fully satisfactory, and several studies have been conducted to improve them. This review covers traditional and newer concepts regarding seminal vesiculitis, including diagnostic and treatment methods, management of stallions with this disorder, and authors' experience with clinical cases.

An approach to rescue the fertility of stallions with a high level of hemospermia

A high amount of blood and not the mere presence of blood in equine semen impacts fertility. The aim of this study was to develop an approach to rescue the fertility of stallions with high hemospermia levels. Semen from 15 stallions was divided into four experimental groups: (a) Control-pure raw semen, (b) WB50-50% (v/v) whole blood added into semen, (c) E1-WB50 extended in a 1:1 (v/v) ratio with milk-based extender and (d) E2-WB50 extended in a 2:1 ratio with milk-based extender. Sperm kinetics, plasma membrane integrity (PMI), lipid peroxidation (PER) and intracellular superoxide (O₂ ) production were immediately evaluated. Four cycles of 20 mares were randomly assigned to the experimental groups. Mares were bred with an insemination dose of 1 billion total sperm and pregnancy was diagnosed 14 days after ovulation. Sperm kinetics could not be evaluated in the WB50 samples. Total motility was lower (p < .05) in E1 than in CT and E2 samples. Progressive motility decreased (p < .05) with an increase in the percentage of blood in the samples. The PMI and PER did not differ between groups (p > .05); however, O₂ production was higher (p < .05) in WB50 than in E2 samples, while the values were intermediate (p > .05) for CT and E1 samples. The control (90%) and E2 (90%) groups had superior (p < .05) fertility than the others (WB50-0% and E1-25%). It was concluded that sperm motility and fertility of semen with a large amount of blood can be rescued by dilution with a 2:1 extender:semen ratio using a milk-based extender.

Fractionated semen collection as a tool to rescue fertility in stallions with seminal vesiculitis

Treatments for seminal vesiculitis have poor outcomes in stallions; thus, the development of alternative strategies is warranted. This study aimed to evaluate fractionated semen collection as a method to restore the fertility of stallions diagnosed with seminal vesiculitis. Eighteen ejaculates from six stallions (three ejaculates/stallion) diagnosed with seminal vesiculitis were harvested in fractions, as follows: Fraction A (FA), the first two jets; Fraction B (FB), the third and fourth jets; and Fraction C (FC), the fifth and remaining jets of the ejaculate. All fractions were subject to standard semen evaluations that were performed in addition to cytology and bacterial aerobic cultures. Fractions were extended and cooled to 5 °C. As a proof of concept, 20 mares (48 estrous cycles, ∼8 cycles/stallion) were bred with 1 billion sperm from FA (cooled at 5 °C for 24 h). In our study, FA had negative bacterial cultures, absent macroscopic or microscopic abnormalities; FB had positive bacterial cultures in two stallions and presence of polymorphonuclear neutrophils (PMNs) in all samples, but with no macroscopic abnormalities; and FC had positive bacterial cultures, purulent appearance, and the presence of degenerated PMNs, just as noted in the whole semen. Overall, post-cooling sperm motility results were superior (P < 0.05) for FA in comparison with FB and FC. First cycle pregnancy rates using FA varied from 66% to 86%. None of the non-pregnant mares developed endometritis. In conclusion, fractionated semen collection can be used to obtain semen free of contamination and to achieve satisfactory pregnancy rates from stallions with seminal vesiculitis.