Evaluation of equine oocyte developmental competence using polarized light microscopy.

The purpose of this study was to observe in vitro-matured equine oocytes with an objective computerized technique that involves the use of a polarized light microscope (PLM) in addition to the subjective morphological evaluation obtained using a classic light microscope (LM). Equine cumulus-oocyte complexes (COCs, n = 922) were subjected to different in vitro maturation times (24, 36 or 45 h), however, only 36-h matured oocytes were analyzed using CLM. The 36-h matured oocytes that reached maturity were parthenogenetically activated to evaluate the quality and meiotic competence. Average maturation percentages per session in groups 1, 2 and 3 (24-, 36- and 45-h matured oocytes respectively) were 29.31 ± 13.85, 47.01 ± 9.90 and 36.62 ± 5.28%, whereas the average percentages of immature oocytes per session were 28.78 ± 20.17, 7.83 ± 5.51 and 22.36 ± 8.39% respectively. The zona pellucida (ZP) birefringent properties were estimated and correlated with activation outcome. ZP thickness and retardance of the inner layer of the zona pellucida (IL-ZP) were significantly increased in immature oocytes compared with mature oocytes (P < 0.001 and P < 0.01 respectively). The comparison between parthenogenetically activated and non-activated oocytes showed a significant increase in the area and thickness of the IL-ZP in parthenogenetically activated oocytes (P < 0.01). These results show that the 36-h in vitro maturation (IVM) protocol allowed equine oocytes to reach maturity, and PLM observation of ZP can be used to distinguish mature and immature oocytes as well as activated and non-activated oocytes.

Antimicrobials administration, treatment outcome and bacterial susceptibility in canine pyometra cases subjected to ovariohysterectomy.

Pyometra is a bacterial uterine infection that frequently affects intact older bitches. The treatment of choice is ovariohysterectomy, often associated with perioperative antimicrobial therapy. The aim of this retrospective investigation was to evaluate the antibiotic choice at different administration times (pre-surgery, at surgery/during hospitalization, and post-surgery) against complications and outcomes, considering the susceptibility profile of bacteria. The medical records of 51 bitches referred to the Veterinary Teaching Hospital of the University of Turin (January 2021-November 2023) and subjected to ovariohysterectomy and bacteriological examination (bacterial culture and susceptibility tests) of the uterine exudate, were analysed. All animals had a positive outcome without surgical site infections, with a longer hospitalization time in case of peritonitis or sepsis; antimicrobials were administered for an average of 7 days. Comparing the susceptibility of the isolated bacteria towards the antimicrobials administered before, during and after surgery, complete efficacy was observed in 42 %, 46 % and 50 % of cases, respectively. In addition, 5/16 peritonitis cases were treated with an in vitro ineffective antimicrobial, and 30 % of the bitches never received a fully effective antibiotic, according to susceptibility tests using the minimum inhibitory concentration method (MIC). Cephazolin resulted the best option for Escherichia coli, the most frequently isolated bacterium. Our study confirms that pyometra has a good prognosis following ovariohysterectomy and antibiotic administration. Monitoring the clinical evolution without changing the antibiotic according to bacterial susceptibility could represent the right choice in uncomplicated cases. Evaluation of outcomes without postoperative antibacterial treatment or with a shorter course would be another topic worth investigating, with the aim to judiciously reduce the use of antibiotics.