Background: Castration of the stallion is one of the most frequently performed surgical procedures in the horse. Recently barbed suture materials for surgical wound closure were introduced to the market with manufacturers claiming that these sutures enhance speed and security as they eliminate the need to tie knots. Recently, it has been suggested that this type of suture may increase postoperative complications. This study aimed at investigating and comparing a bidirectional absorbable knotless barbed suture (KBS) to a conventional smooth suture (SS) for wound closure of inguinal castrations in the horse. This was done by evaluating short-term and post-discharge complications and by comparing the time spent on suturing the surgical wounds after bilateral inguinal castration, which was performed on 45 horses undergoing castration at The Large Animal Teaching Hospital at University of Copenhagen from September 2017 to May 2019. Results: Short-term complications were few; at 24 h minor swelling occurred in 29 and 33% of horses sutured with KBS and SS respectively and cutaneous dehiscence during recovery occurred in two horses of each group. Post-discharge follow-up revealed that three horses needed veterinary attention for treatment of complications (scrotal swelling (n = 1, KBS); wound exudation (n = 1, SS) and wound dehiscence after return to pasture (n = 1, SS)). Wound closure was achieved 6 min faster with KBS than with SS (P < 0.0001). Conclusions: Use of the KBS suture did not result in increased occurrence of postoperative complications. Wound closure was faster with KBS than with SS in equine bilateral inguinal castration. Our results show that KBS can safely be used in the horse following bilateral inguinal castrations without adverse effects and with a reduction in suturing time.