Significant changes occur in the ultrasonographic appearance of the lungs in horses following exploratory celiotomy.

Overview

• This study investigated how the lung appearance changes on ultrasound in horses after exploratory celiotomy surgery.
• The researchers identified significant but temporary lung ultrasonographic changes following surgery and potential risk factors contributing to these changes.

Background and Rationale

• General anesthesia for short elective procedures in healthy horses typically causes minimal changes visible on lung ultrasound (thoracic ultrasonography, TUS).
• The impact of general anesthesia combined with exploratory celiotomy—a more invasive abdominal surgery—on lung ultrasound appearance had not been studied previously.
• Understanding these changes helps clinicians anticipate and manage potential lung complications after surgery.

Study Objectives

• To quantify the degree of ultrasonographic changes in the lungs of horses after undergoing exploratory celiotomy.
• To identify clinical risk factors that may increase the severity of these ultrasonographic changes.

Methods

• Prospective observational study design enrolling 63 horses aged ≥ 2 years undergoing exploratory celiotomy.
• Data collected included:
  • Signalment (age, breed, sex), weight, physical exam findings, clinicopathologic data.
  • Details of the surgical lesion and the procedure performed.
  • For horses that survived surgery:
    • Duration of recumbency (laying down time) after surgery.
    • Which side the horse recovered on (laterality).
    • Presence of reflux (backflow of stomach contents) or feed material on the endotracheal tube during recovery from anesthesia.
  • Thoracic ultrasonography was performed at four time points: before surgery (pre-operative), and 1, 3, and 5 days post-operatively.
• Statistical analysis used a linear mixed model with Bayesian estimation to examine the effects of time and clinical groups on TUS scores, with significance set at P < 0.05.

Key Results

• Survival rate was 82.5% (52 out of 63 horses survived surgery).
• The pre-operative TUS score was not predictive of survival.
• TUS scores on Day 1 post-operation were significantly increased compared to pre-operative scores, indicating acute lung changes following surgery:
• Median Day 1 TUS score was 25.94 (95% credible interval [CrI]: 10.47-41.50).
• Pre-operative median TUS score was 21.19 (95% CrI: 9.75-32.50).
• The change in TUS score from pre-operation to Day 1 was significantly associated with:
• The presence of feed material on the endotracheal tube during extubation (P = 0.03).
• Reflux occurring in recovery (P = 0.006).
• These lung ultrasonographic changes appeared to resolve over time, indicating they were self-limiting rather than progressive.

Interpretation and Implications

• Exploratory celiotomy in horses is associated with notable but temporary changes in lung ultrasound appearance within the first postoperative day.
• The presence of feed or reflux during anesthesia recovery might reflect aspiration risk or other complications that worsen lung ultrasonographic findings.
• These findings suggest perioperative management should include careful monitoring to minimize aspiration risk, as this may influence pulmonary status after surgery.
• Clinicians can expect these ultrasonographic lung changes to improve over a few days without additional intervention in most cases.

Limitations and Future Directions

• The study was observational and limited to horses undergoing exploratory celiotomy; results may not be generalizable to other surgeries or species.
• Long-term effects beyond 5 days were not evaluated.
• Further studies could investigate strategies to reduce reflux and aspiration during recovery to improve pulmonary outcomes.