Digital vascular responses and permeability in equine alimentary laminitis.
Authors: Robinson, Scott, Dabney, Jones
Journal: American journal of veterinary research
Summary
# Editorial Summary Robinson *et al.* investigated the vascular haemodynamic changes occurring in the equine digit during alimentary laminitis induced by high-starch feeding, measuring digital blood flow, arterial and venous pressures, vascular resistances, lymph dynamics, and responses to common vasoactive agents in 8 laminitic animals compared to 11 controls. The laminitic group demonstrated significantly elevated digital blood flow alongside increased arterial, small vein, and large vein pressures, coupled with reduced overall vascular resistance—a pattern consistent with vasodilation in the affected digits. Notably, digital lymph flow rates and protein concentrations were unchanged between groups, and both laminitic and control animals showed identical vascular responses to acetylcholine, epinephrine, histamine, and serotonin, suggesting that the observed hyperaemia was not mediated by differential responsiveness to these vasoactive mediators or by increased capillary permeability. These findings challenge earlier assumptions about the pathophysiology of laminitic digits and indicate that the increased blood flow observed in acute laminitis results from mechanisms other than endothelial permeability changes or altered sensitivity to common inflammatory mediators. For practitioners, this work suggests that understanding laminitis-associated digital blood flow disturbances requires investigation beyond simple vasoreactivity or increased vascular leakage, potentially pointing towards central circulatory regulation or mechanical obstruction as contributory factors.
Read the full abstract on PubMed
Practical Takeaways
- •High-starch diets cause measurable changes in digital hemodynamics in laminitis, but these changes appear to result from altered vascular tone rather than permeability issues or chemical sensitivity
- •Standard vasoactive drugs may not effectively reverse the vascular changes seen in laminitis, suggesting alternative therapeutic approaches may be needed
- •Understanding that increased blood flow in laminitic digits is a primary vascular event helps direct focus toward managing underlying causes rather than secondary inflammatory responses
Key Findings
- •Animals with laminitis demonstrated increased digital blood flow, increased arterial/venous pressures, and decreased vascular resistances compared to controls
- •No differences in digital lymph flow rates or protein concentrations between laminitic and control animals
- •Digital vascular responses to acetylcholine, epinephrine, histamine, and serotonin did not differ between laminitic and control groups
- •Increased digital blood flow in laminitis could not be attributed to altered responsiveness to vasoactive agents or increased capillary permeability