Response of three digital anesthetic technics in horses with forelimb hoof lameness

ABSTRACT The presented study aimed to assess objectively the response of distal interphalangeal joint (DIJ), navicular bursa (NB) and deep digital flexor tendon sheath (DDFTS) anesthesia in horses with forelimb hoof lameness; and evaluate if the presence of radiographic abnormalities on navicular bone could interfere on blocks’ results. Fifteen horses with lameness improvement above 70% after palmar digital nerve (PDN) block were selected for this study. Blocks were assessed separately on five consecutive trials at seven different time-points. The fifth trial was performed to evaluate the influence of exercise on preexisting lameness. Most of horses (73.33%) presented pain related to the podotrochlear apparatus based on clinical and lameness exam and blocks’ responses. NB and DIJ anesthesia differed on the frequency of horses with lameness improvement above 70% only at 10min (p=0.03), and both differed from DDFTS block until 30’(p<0.05). The blocks’ response was variable along the time and the highest means for NB, DIJ and DDFTS were observed at 5-10 minutes (’), 15-20’ and 10-15’ respectively.Exercise had low interference on lameness intensity since no improvement above 50% was observed and an increase on lameness intensity over time was identified in seven horses. Variable grades of navicular bone radiographic lesions were observed in 14 horses, although these lesions had no interference on blocks’ response (p>0.05). The NB and DIJ blocks had similar responses and both were superior to DDFTS anesthesia, coincident with a major prevalence of podotroclear apparatus abnormalities in this equine population.摘要 本研究旨在客观评估前肢蹄跛行马匹的远端指间关节（distal interphalangeal joint, DIJ）、舟状骨囊（navicular bursa, NB）及指深屈肌腱鞘（deep digital flexor tendon sheath, DDFTS）阻滞的反应，并探讨舟骨影像学异常是否会对阻滞效果产生干扰。本研究选取了15匹经掌侧指神经（palmar digital nerve, PDN）阻滞后跛行改善率超过70%的马匹作为研究对象。在五次连续的试验中，分别于七个不同时间点对阻滞效果进行评估，其中第五次试验用于评估运动对原有跛行的影响。结合临床检查、跛行评估及阻滞反应结果，绝大多数马匹（73.33%）存在与蹄软骨复合体相关的疼痛。仅在10分钟时，NB与DIJ阻滞在跛行改善率超70%的马匹占比上存在显著差异（p=0.03）；且二者在30分钟内均与DDFTS阻滞效果存在统计学差异（p<0.05）。阻滞效果随时间呈现动态变化，NB、DIJ及DDFTS阻滞的最高平均改善率分别出现在5-10分钟、15-20分钟及10-15分钟时段。运动对跛行强度的影响较低，未观察到跛行改善率超过50%的情况，且有7匹马的跛行强度随时间出现升高。14匹马存在不同程度的舟骨影像学病变，但此类病变未对阻滞效果产生显著干扰（p>0.05）。NB与DIJ阻滞效果相似，且二者均优于DDFTS阻滞，这与本研究马群中蹄软骨复合体异常的高患病率相契合。