Planimetric and stereological characteristics of lateral and medial palmar nerves in hands of equine with and without navicular syndrome

Navicular Syndrome (NS) is one of the most frequent claudicogen pathologies in the equine clinical practice. Certain individual susceptibility has been described in this clinical presentation, that is, some horses with SN halt, while others with similar radiographic findings in hand do not, suggesting that there are quantitative differences, between horses with and without clinical presentation of SN, on the characteristics of the nerve fibers of the peripheral nerves of the hand. The aim of this study was to describe the morphologic quantitative characteristics of the lateral and medial palmar in horses with SN nerves. Hands were obtained by sampling directed and diagnosed by visual inspection and radiographic evaluation. Two groups were formed: "Not affected" (n= 6) and "Navicular Syndrome" (n = 8). To determine quantitative differences between two groups we performed: i) Study 1: evaluated the morphological, planimetric and stereological lateral and medial palmar nerves, ii) Study 2: evaluated the number of unmyelinated and myelinated axons. In both studies, analysis of stereological, morphological and planimetric data generally detected no significant differences between groups. In conclusion, the results of the study do not provide morphological evidence for differences between palmar nerves between horses with and without SN.