Evaluation of fluorescein dye as an indicator of small intestinal viability in the horse.

This research investigates fluorescein dye as a method for determining the health and blood flow of horse intestines during and after ischemic incidents. It found that fluorescein effectively detects perfusion, but does not alone provide a full prognosis for clinical outcomes.

Methodology

• The researchers used 6 horses for the study. They artificially induced two types of ischemic lesions (areas of tissue decay due to lack of blood flow) in the horses’ small intestinal segments. They achieved this by selectively constricting blood vessels and intestinal wall sections for a duration of 1, 2 or 3 hours.
• Once ischemia (restricted blood flow leading to insufficient oxygen supply) was confirmed, they administered an intravenous (IV) injection of sodium fluorescein. Fluorescein is a dye that fluoresces under UV light, allowing researchers to track its path through the bloodstream and hence gauge blood flow.
• After releasing the ligations and waiting for five minutes, the researchers then documented fluorescein patterns via photography.

Findings

• Fluorescein dispersion patterns varied from normal, as seen in healthy, unaffected bowel tissue, to patchy, in areas with incomplete perfusion – indicative of compromised blood circulation.
• Of note, one month after the experiment, none of the manipulated intestinal segments returned to a normal state. The treated sites manifested fibrosis (fibrous tissue development), adhesion (abnormal sticking together of tissues), and thickening of the bowel wall. This suggests lasting damage from the induced ischemia.

Conclusion

• The study confirmed that injecting fluorescein intravenously serves as a valuable tool to assess perfusion in horse intestines. Its visualization allows for an understanding of the extent and patterns of ischemia.
• Nevertheless, the research also highlights that fluorescein-based perfusion assessment doesn’t provide a complete clinical prognosis for cases of intestinal ischemia in horses. The dye can indicate how well the tissue is being perfused, but it does not offer information on the restoration of the intestines to full normal functioning or about the long-term effects of the ischemia.