Experimental comparative study of perineural injection of benzyl alcohol 0,75% and absolute ethyl alcohol in equine palmar nerves

The clinical and histopathological effects of two alcoholic neurolytics were studied in horses. Normal horses were shod with a designed shoe adaptted with 5 screws to produce solar pain. After gait and lameness score analysis, the palmar nerve of 5 horses was injected with 5 ml of 0,75% benzyl alcohol (Group A) and 5 horses were injected with 5 ml of absolute ethyl alcohol (Group B). The animals were submitted to regular lameness evaluation and solar sensibility tests during next six months. The solar sensitivity returned 5 months latter in the group injected with benzyl alcohol 0,75%, while in the group injected with absolute ethyl alcohol, the sole was still desensitized 6 months latter. The histopathological findings showed that the nerve injected with benzyl alcohol 0,75%, resulted in axonotmesis, characterized by axonal nerve degeneration, with possibilities for the nerve conduction recovery. The perineural injection of ethyl alcohol absolute, resulted in neurotmesis with difficult nerve regeneration. It was concluded that chemical neurolysis with alcohol is an option for temporary or permanent nerve blocks in horses. Foi estudada a neurólise química dos nervos Palmares em 10 eqüinos. Usando-se uma ferradura especial para induzir claudicação, a locomoção avaliada ao passo e trote e os graus foram registrados antes e após a injeção perineural do álcool benzílico 0,75% (Grupo A) e o álcool etílico absoluto (Grupo B). Os testes mostraram que ambos os neurolíticos dessensibilizaram completamente a sola dos animais a partir de 30 dias, assim permanecendo até o 150º dia nos animais do Grupo A, quando ocorreu retorno progressivo da sensibilidade. Já no Grupo B, aos 180 dias, a sensibilidade permanecia ausente. A análise histopatológica revelou que nos nervos infiltrados com álcool benzílico 0,75% prevaleceram lesões próprias de axonotemese, sugerindo tendência de regeneração e restabelecimento da condução nervosa, enquanto que nos nervos infiltrados com álcool etílico absoluto, prevaleceram lesões simuladoras de neurotemese, com degeneração nervosa permanente. Concluiu-se que os álcoois utilizados foram eficientes bloqueadores temporários ou permanentes dos nervos Palmares em eqüinos.