# Post-Ejaculatory Blood Plasma Canine Prostate-Specific Esterase Concentrations May Predict Total Motility Decline After Sperm Freezing in Dogs

## TL;DR

Measuring a prostate protein in dog blood after ejaculation may predict how well their sperm survives freezing, helping improve breeding practices.

## Contribution

Identified post-ejaculatory canine prostate-specific esterase as a potential biomarker for predicting sperm freezability.

## Key findings

- Dogs with lower CPSE levels had better sperm motility before and after freezing.
- A CPSE threshold of 53 ng/mL predicted ≥20% motility decline after thawing (AUC = 0.785).
- CPSE correlated strongly with total motility (p = 0.004) as a freezability indicator.

## Abstract

Freezing dog semen is important for breeding and genetic preservation, but sperm from some dogs are more easily damaged by freezing than others. At present, there is no simple way to predict which dogs produce semen that freeze well. In this study, we investigated whether the amount of a protein released by the prostate gland is related to how well sperm survives freezing and thawing. We found that dogs with lower levels of this protein generally had better sperm quality, including better movement, both before freezing and after thawing. A specific blood level was identified that helped distinguish dogs whose sperm were more sensitive to freezing. These results suggest that measuring this protein in blood after ejaculation could help predict whether a dog’s semen is suitable for freezing. This information may help veterinarians and breeders improve semen freezing success and avoid unnecessary procedures.

Despite the widespread use of cryopreserved dog semen, reliable predictors of individual semen freezability are still not available. This study investigated the relationship between post-ejaculatory blood plasma concentrations of canine prostate-specific esterase (CPSE) and semen quality following cryopreservation. The CPSE levels were quantified using a canine-specific sandwich-type immunoassay, and sperm quality was evaluated in fresh and frozen–thawed samples using motility, kinematic, and morphological sperm parameters. Cryopreservation resulted in a significant decline in sperm motility and morphology, with marked variability in the magnitude of post-thaw changes among individuals. CPSE showed significant correlations with several morpho-functional parameters in both fresh and frozen–thawed sperm (p ≤ 0.05). However, its strongest predictive value for freezability was observed for total motility (p = 0.004), with a minimum threshold of 53 ng/mL identifying dogs showing a ≥20% post-thaw motility decline (AUC = 0.785, p = 0.010). These findings suggest that post-ejaculatory CPSE levels in blood plasma may reflect sperm cryoresilience and serve as a potential biomarker of canine sperm freezability.