Relative potency and duration of analgesia following palmar digital intra-neural alcohol injection for heel pain in horses

Objective: To determine the potency (percent analgesia), duration of action (up to four months), and clinical and histological effects of surgical exposure and intra-neural injection of 98% dehydrated medical-grade ethyl alcohol compared to no treatment (negative control), sham operation (surgical control), or formaldehyde injection (positive control) to decrease experimentally-induced palmar heel pain in horses. Animals: Six horses Procedures: The horses were fitted with a custom pressure-inducing shoe and had outcome measurements for each heel performed before and after nerve treatments. Outcomes included induced lameness grade and vertical peak force with pressure applied to each heel, thermal and touch sensation for each heel, and pastern circumference. Outcomes were followed serially for 112 days when nerves were harvested for histology. Results: Alcohol and formaldehyde reduced all measures of heel pain which progressed toward return, but persisted over the 112 days of the study (P<0.05). Pastern circumference was not different for alcohol than sham treatment, but was greater in formaldehyde than alcohol or baseline (P<0.05). Histological evaluation showed preservation of nerve fiber alignment with an intact epineurium, loss of axons (axon drop out), axon degeneration, fibrosis and inflammation in alcohol- and formaldehyde-injected nerves compared to control nerves. Formaldehyde injection induced greater fibrosis and inflammation than alcohol.Conclusions and Clinical Relevance: Alcohol injection induced effective neural blockade for months with evidence that nerve structure and function could return. Formaldehyde injection showed no advantage over alcohol and is not recommended under the conditions of our study due to soft tissue inflammation.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Veterinary Clinical Sciences

Grantor dc:publisher

The Ohio State University

Year dc:date

2013

Author dc:creator

• Schneider, Christine Pariseau

Contributors dc:contributor

• Bertone, Alicia

• Veterinary Services

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=osu1364991994

OAI identifier oai:identifier

oai:etd.ohiolink.edu:osu1364991994