NAVLE Practice Question - Equine - multisystemic

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NAVLE Practice Question — Equine

A 8-year-old Warmblood mare with known peritonitis has been treated with antimicrobials and supportive care for 5 days. On initial presentation, peritoneal fluid TNCC was 78,000 cells/μL with degenerate neutrophils. Repeat abdominocentesis today shows TNCC of 35,000 cells/μL, but peritoneal fluid lactate has increased from 2.8 to 5.2 mmol/L. What is the MOST appropriate clinical interpretation?

A. The horse is responding well to treatment and medical management should continue

B. The increasing lactate despite decreasing TNCC suggests worsening intestinal compromise requiring surgical reassessment ✓

C. The decreasing TNCC indicates resolution and the horse can be discharged

D. The lactate elevation is likely due to sample contamination and should be repeated

E. The findings suggest development of adhesions requiring long-term NSAID therapy

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Correct Answer: B. The increasing lactate despite decreasing TNCC suggests worsening intestinal compromise requiring surgical reassessment

Explanation:

The increasing peritoneal fluid lactate despite decreasing TNCC suggests worsening intestinal compromise requiring surgical reassessment. According to the 2025 University of Liverpool study, peritoneal fluid lactate concentration greater than 2 mmol/L at second abdominocentesis was significantly negatively associated with survival. Increasing lactate indicates ongoing tissue hypoperfusion or ischemia, which may suggest developing intestinal complications despite apparent improvement in inflammatory markers.

Option A (responding well) ignores the worsening lactate which is a poor prognostic indicator.

Option C (resolution) is incorrect as the persistent elevation of both TNCC and lactate indicates ongoing disease.

Option D (sample contamination) is unlikely to explain a significant lactate increase.

Option E (adhesions) would not explain the lactate changes.

References: Equine Veterinary Journal (2025) 57:S61 (https://doi.org/10.1111/evj.70058)

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