Diffusion of dye after perineural injection of the palmar/plantar nerves in two different sites in horses: an ex-vivo study

This study aimed to evaluate the distribution of dye at two perineural injection sites of the palmar/plantar nerves and describe their anatomical variations of positioning at the level of the distal metacarpus/metatarsus in horses. Two ml of 1% methylene blue solution was injected in 24 limbs (12 forelimbs and 12 hindlimbs) of horse cadavers at two different points: Group 1: between the branch of the suspensory ligament and deep digital flexor tendon, and Group 2: between the deep and superficial digital flexor tendons. This was followed by dissection and evaluation of the solution diffusion. A photographic record and description of the anatomical position of the palmar/plantar nerve were performed. A comparison of diffusion directions in each portion (medial or lateral) between groups showed no statistical difference ( P > 0.05), except in the dorsal direction on the medial portion of hindlimbs, which was higher in Group 2 ( P = 0.025). The digital flexor tendon sheath was inadvertently injected four times into the forelimbs of Group 2. Both injection sites offered good dye contact with the palmar/plantar nerves, with the position between the deep digital flexor tendon and suspensory ligament branch having a higher contact area, regardless of the limb portion. The anatomical position of the palmar/plantar nerve in the cadaver specimens was similar between the same limb portions.