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

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.