# Surgical Assessment and Post-Operative Complications Following Video-Assisted Thoracoscopic Surgery (VATS) of Horses with Severe Equine Pasture Asthma During Asthma Exacerbation and Remission

## TL;DR

This study examines surgical outcomes and complications in horses with severe Equine Pasture Asthma undergoing VATS, finding longer surgical times and higher complication rates during asthma exacerbations.

## Contribution

The study provides the first detailed evaluation of VATS outcomes in horses with severe Equine Pasture Asthma during exacerbation and remission.

## Key findings

- Surgical times were significantly longer in EPA-affected horses during asthma exacerbation compared to control horses.
- Post-operative complications occurred in 54% of procedures, including fever, colic, and surgical site infections.
- Lung hyperinflation was observed only in EPA horses during asthma exacerbation, increasing surgical difficulty.

## Abstract

Information on the post-operative complications and treatment of horses undergoing Video-Assisted Thoracoscopic Surgery (VATS) is limited. Postoperative outcome with long-term follow-up has not been described, nor has any study evaluated thoracic surgery in horses with severe Equine Pasture Asthma (EPA). This study evaluated the incidence of complications and surgical time in severe EPA horses with clinical disease, severe EPA horse in remission without clinical disease, and matched healthy, non-diseased horses undergoing thoracoscopy or conversion to thoracotomy for large pulmonary tissue biopsies using an endoscopic stapling device. Video-Assisted thoracoscopic surgery was performed on horses with EPA during asthma exacerbation and remission, and on their paired healthy control horse counterparts. This study found that during asthma exacerbation, which is triggered by grazing pasture in hot humid conditions (summer), surgical times in EPA horse were significantly longer. Horses with severe EPA may also experience lung hyperinflation which increases surgical difficulty. Complications associated with VATS and post-operatively are described.

The aim of this retrospective clinical study was to assess surgical duration and surgical and post-operative complications associated with Video-Assisted Thoracoscopic Surgery (VATS) and lung biopsy in horses with severe Equine Pasture Asthma (EPA) and paired control horses. Twelve horses (6 EPA-affected, 6 control) were sex, age and breed matched. Twenty-four thoracic surgeries were performed. Surgery of each matched pair (EPA-affected and healthy) was performed during asthma exacerbation (summer) and remission (winter). Surgical times were shorter with uncomplicated thoracoscopy (85 min) and significantly longer (p < 0.001) when intra-operative complications necessitated conversion to thoracotomy (156 min). The overall surgical time of EPA-affected horses during asthma exacerbation was significantly longer than control horses at any time point, predicted mean difference of 78 min (p < 0.05). When comparing EPA-affected horses to themselves during asthma exacerbation and remission, surgical times were significantly longer (p < 0.01) with a predicted mean difference of 98 min; this effect of seasonality did not occur amongst control horses. Intra-operative surgical complications (6/24) were evenly divided between EPA and control horses, however, only severe EPA horses in exacerbation were noted to have lung hyperinflation. Post-operative complications: fever, colic, hemothorax, pneumothorax, subcutaneous emphysema, surgical site infection, and/or laminitis occurred in 13/24 surgical procedures (54%). No fatalities resulted from these procedures.