A comparison of responses to analgesia of the navicular bursa and intra-articular analgesia of the distal interphalangeal joint in 59 horses.

Analgesia of the distal interphalangeal (DIP) joint and of the navicular bursa was performed independently in the lame or lamer forelimb of 59 horses, in which lameness was significantly improved by perineural analgesia of either the palmar digital or palmar (abaxial sesamoid) nerves. In 3 horses no improvement was detected. Lameness was improved by analgesia of the DIP joint but there was no response to analgesia of the navicular bursa in 3 horses. In 12 horses, lameness was improved by analgesia of the navicular bursa but intra-articular analgesia resulted in no change. Forty-one horses responded both to analgesia of the navicular bursa and intra-articular analgesia of the DIP joint. Synovial fluid was retrieved from all DIP joints but from only one navicular bursa. It is suggested that a positive response to analgesia of the DIP joint does not necessarily imply that pain arises from the joint per se, but a positive response to intra-bursal analgesia probably reflects pathology of the bursa per se, the navicular bone and/or supporting ligaments and/or the DDFT. Radiographic abnormalities of the navicular bone in the lame or lamer limb were detected in 35 horses, all of which showed some response to analgesia of the navicular bursa. In 25 of these horses (71%) changes were only identifiable in the palmaroproximal-palmarodistal oblique views.(ABSTRACT TRUNCATED AT 250 WORDS)