Long-term assessment of nephrosplenic space closure in horses.

Overview

• This study evaluated the long-term effectiveness of laparoscopic nephrosplenic space (NSS) closure in horses by assessing adhesion formation five years post-surgery.
• It compared the utility of rectal palpation and ultrasonography as diagnostic tools to predict the adequacy of these adhesions in preventing colon entrapment.

Background

• The nephrosplenic space is an anatomical region in horses where colon entrapment can occur, leading to colic, a serious and potentially life-threatening condition.
• Surgical closure of the NSS via laparoscopic ablation is a preventative intervention aimed at reducing the risk of colon entrapment by promoting adhesion formation between the spleen and the kidney.
• Although effective in the short term, long-term data on the durability of these adhesions and the reliability of non-invasive assessment methods (rectal palpation and ultrasonography) have been limited.

Study Design and Methods

• Twelve research horses underwent laparoscopic ablation for NSS closure.
• The NSS was examined at three time points: before surgery, 30 days after surgery, and five years after surgery, using rectal palpation and ultrasonography.
• Ultrasonographic measurements focused on the distance between the renal fascia and the spleen to assess space closure over time.
• At the five-year mark, laparoscopy was used to directly visualize and score the adhesions with a novel adhesion scoring system, quantifying the extent and strength of adhesions.
• Statistical analyses, including logistic regression, were performed to evaluate correlations between surgical variables, imaging findings, and adhesion adequacy.

Key Findings

• Out of 11 horses assessed (one horse’s data was presumably unavailable or excluded), 8 had strong adhesions occupying more than 50% of the NSS, deemed adequate to prevent colon entrapment.
• Three horses exhibited adhesions that were inadequate for prevention of colon entrapment, highlighting some variability in surgical outcomes.
• Ultrasonographic measurements at the caudal NSS showed a significant decrease in space over time, indicating some closure, but these measurements did not reliably predict the effectiveness or adequacy of adhesion formation.
• Rectal palpation was found to be a reliable clinical method for assessing NSS closure and adhesion adequacy.
• Surgical factors such as duration of surgery, number of suture bites taken, or intraoperative bleeding did not have a predictive relationship with adhesion quality or success.

Clinical Implications

• Laparoscopic NSS closure provides durable adhesions lasting at least five years in the majority of horses, offering a sustained preventative measure against colon entrapment.
• Rectal palpation remains a valuable and practical tool for veterinarians to monitor NSS closure without the need for more complex imaging techniques.
• Ultrasonography has limited utility for this purpose, primarily due to bowel interference obscuring views and poor correlation with adhesion strength.
• These findings support the continued use of laparoscopic NSS closure as a preventative surgical intervention and suggest that veterinarians can confidently use rectal palpation for long-term follow-up evaluations.
• The study’s results may encourage greater client confidence and adherence to this surgical option for horses at risk of NSS colon entrapment.

Conclusions

• The study confirms that laparoscopic closure of the nephrosplenic space is effective in forming long-lasting adhesions that help prevent colon entrapment in horses.
• Rectal examination is a reliable and accessible method for assessing the success of the procedure over the long term.
• Ultrasound imaging is less reliable for this purpose and should not be solely relied upon to predict adhesion adequacy.
• Understanding these outcomes can improve postoperative management and owner communication regarding expectations for horses undergoing NSS closure surgery.