A Retrospective Analysis of Liberal Fluid Therapy and Total Protein Changes in 124 Horses Undergoing Colic Surgery.

Overview

• This study analyzed the effects of a liberal fluid therapy strategy on blood protein levels and overall outcomes in horses undergoing colic surgery.
• It retrospectively examined how fluid administration influenced total plasma protein (TPP) and recovery, suggesting TPP as a potential marker for guiding fluid therapy.

Background and Rationale

• Colic surgery in horses often requires careful management of fluid therapy to maintain stable blood volume and pressure.
• Both insufficient (hypovolaemia) and excessive fluid administration (hypervolaemia) can cause complications.
• Current practices vary, and there is a need for measurable indicators to tailor fluid therapy better.
• Total plasma protein (TPP) levels reflect blood concentration status and might serve as a useful marker for fluid balance changes.

Study Design

• Retrospective review of medical records from 124 horses undergoing colic surgery between March 2018 and June 2020.
• Collected data included packed cell volume (PCV) and TPP at several time points: preoperative, immediately post-surgery, postoperative days 2, 5, 7, and at long-term follow-up.
• Horses categorized based on postoperative TPP (≤5 g/dL vs. >5 g/dL) and lesion type (strangulating vs. non-strangulating intestinal lesions).
• Fluid therapy involved:
  • Crystalloids administered to all horses (median dose 34.3 mL/kg, range 9-99 mL/kg).
  • Colloids (HES 130/0.4) given to 41 out of 124 horses at 4 mL/kg.

Key Findings

• TPP significantly decreased immediately after anesthesia recovery compared to admission levels at the population level.
• Horses with TPP ≤ 5 g/dL after recovery received more total crystalloids than those with TPP >5 g/dL (56.8 vs. 31.5 mL/kg), indicating a strong association between fluid volume and TPP reduction.
• PCV changes were similar between groups, suggesting that TPP might be a more sensitive indicator of haemodilution from fluid therapy than PCV alone.
• Statistical adjustments considering lesion severity and the segment of intestine involved upheld the link between crystalloid dose and TPP reductions, although residual confounding by disease severity variables could not be entirely ruled out.
• Greater total crystalloid use correlated with larger drops in TPP, supporting the notion that liberal fluid therapy induces haemodilution.
• Horses with lower postoperative TPP (≤5 g/dL) had significantly longer hospital stays, implying that this low TPP might be associated with delayed recovery or complications.

Implications and Conclusions

• Monitoring TPP serially during and after surgery may provide a practical, real-time biomarker for assessing plasma protein levels and haemodilution status.
• Such monitoring could help individualize fluid therapy to avoid excessive dilution or volume overload.
• The study suggests that total protein reduction reflects the impact of fluid administration more sensitively than packed cell volume.
• However, since this was a retrospective study, prospective validation is needed to confirm the utility of TPP-guided fluid management protocols.
• Further research could explore whether adjusting fluid therapy based on TPP measurements improves clinical outcomes such as hospitalization duration and complication rates.

Limitations

• Retrospective nature limits control over confounding variables, including indicators of disease severity not captured in records.
• The study could not definitively exclude that factors other than fluid dose influenced TPP changes.
• Colloid therapy was inconsistently applied, which might influence TPP and volume status differently than crystalloids alone.