Endothelial glycocalyx thickness in cats with naturally occurring trauma or non-traumatic illness – an exploratory study

Ivayla Danielova Yozova^1*Neroli A Thomson¹Mitsuhiro Irie²Rebecca Louise Owen¹John Munday¹

• ¹School of Veterinary Sciences, College of Sciences, Massey University, Palmerston North, New Zealand
• ²Shikoku Veterinary Medical Center, Miki 761-0701, Japan

Abstract Introduction: Endothelial glycocalyx damage contributes to morbidity and mortality in critical illness. In this exploratory study in cats with trauma and non-traumatic illness, the endothelial glycocalyx thickness was estimated using sidestream dark field videomicroscopy and the GlycocheckTM software, with the primary aims of assessing feasibility, describing of GlycocheckTM microcirculatory parameters and exploring potential effects of illness severity and IV fluid administration. Methods: This was a prospective, single centre, observational study. Recorded variables included age, weight, diagnosis, length of hospitalization (LOH), packed cell volume (PCV) and IV fluid administration. Each patient was assigned a fast Acute Patient Physiologic and Laboratory Evaluation score (APPLEfast) and for cats with trauma - Animal Trauma Triage score (ATT). Within 24h from admission, cats were anaesthetised, and images from the sublingual mucosal vessels obtained for GlycocheckTM analysis. The perfused boundary region (PBR), an inverse estimate for endothelial glycocalyx thickness, was calculated for vessels with diameter of 5-25, 5-9, 10-19 and 20-25 µm, respectively. Normality was assessed using Shapiro-Wilk test and histograms. The effects of APPLEfast, LOH, ATT, PCV, IV fluid administration, and illness group on PBR were analysed using generalised linear models. Distribution of vascular segment counts was assessed using Friedman's test and Wilcoxon rank-signed test. Results: Nineteen cats were included, 11 with trauma. Success rate for measurements was 95%. Survival to discharge was 95%. Mean ± standard deviation for PBR 5-25 was 2.60±0.22 µm, PBR 5-9: 1.38±0.15 µm, PBR 10-19: 3.02±0.22 µm and PBR 20-25: 3.03±0.38 µm, within previously established tolerance intervals. There were no statistically significant effects of group, LOH, ATT, APPLEfast, PCV and IV fluids on any PBR measurements. Vascular segment counts across the 5 – 25 µm range were not equally distributed (p<0.001). Conclusion: This exploratory study demonstrates the feasibility of assessing endothelial glycocalyx thickness in hospitalized sick cats. While no effects of clinical variables on PBR were identified, the study highlights important methodological considerations and provides valuable insights to guide future, larger-scale investigations.