A comparison of the effects of local analgesic solution in the navicular bursa of horses with lameness caused by solar toe or solar heel pain

Abstract

Summary We hypothesised that analgesia of the navicular bursa is not selective for the navicular apparatus; and that solar pain in some horses can be temporarily abolished or attenuated by analgesia of the navicular bursa. To test this hypothesis, we caused lameness in horses by inducing pain in the dorsal margin or the angles of the sole and then evaluated the ability of a local analgesic solution administered into the navicular bursa to attenuate lameness. The response of horses with solar pain in the dorsal or palmar aspect of the foot to 3.5 ml local analgesic solution administered into the navicular bursa was examined. Lameness was induced in 6 horses by creating solar pain in the dorsal aspect of one forefoot and, at another time, the palmar aspect of the other forefoot, with set‐screws inserted into a custom‐made shoe. Horses were videotaped trotting before and after application of set‐screws and after administering 3.5 ml local analgesic solution into the navicular bursa. Lameness scores were assigned by examining videotaped gaits. Scores were significantly lower (P<0.05) for all horses with set‐screws applied to the dorsal margin of the sole after administration of local analgesic solution into the navicular bursa. In conclusion, analgesia of the navicular bursa was less effective in desensitising the angles of the sole than in desensitising the dorsal margin of the sole. Pain arising from the sole should not be excluded as a cause of lameness when lameness is attenuated by analgesia of the navicular bursa.

Where does it hurt? Problems with interpretation of regional and intra‐synovial diagnostic analgesia

“…Moreover, contrary to expectations, analgesia was most effective in the toe region of the sole and least effective in the palmar angles of the sole (Schumacher et al . ). A separate study showed that the volume of local anaesthetic solution injected into the DIP joint could influence the portions of the sole that are desensitised (Schumacher et al .…”

“…To confound things further, experimentally‐induced solar pain was improved by injection of local anaesthetic solution into either the DIP joint or the navicular bursa (Schumacher et al . ; Sardari et al . ).…”

Circumferential hoof clamp method of lameness induction in the horse

“…Others fail to provide any data or mention of assessment following removal of lameness induction techniques (Merkens and Schamhardt, 1988b). In contrast to screw placement near the quarters of the hoof, the persistence of lameness has been recognized more frequently when induced with the screws placed toward the toes, such that lameness remained for at least 24 h (Keegan et al, 2000;Schumacher et al, 2000Schumacher et al, , 2001aSchumacher et al, , 2001b.…”

“…For instance, the frog-pressure method, when used on trotting horses, has been shown to produce an inconsistent lameness pattern over time (Keegan et al, 2000;Kelmer et al, 2005). In addition, residual lameness has been reported with the solar pressure technique, with most being in studies where the nuts and screws are placed closer to the toe than the quarter (Deuel et al, 1995;Schumacher et al, 2000Schumacher et al, , 2001aSchumacher et al, , 2001b. The type of screw used may also affect induction of lameness; for example, researchers found greater residual lameness when using flat-tipped screws when compared to pointed screws and it has been speculated that additional pressure and repeated placement may lead to solar bruising (Schumacher et al, 2000(Schumacher et al, , 2001a.…”

Magnetic Resonance Imaging in the foot region of the standing horse

“…Von Dyson et al (2005) Gelenke sehr kritisch bewertet werden (Dyson 1998, Dyson und Marks 2003 (Schumacher et al 2001). Nach Einwirkungszeit des Lokalanästhetikums von 20 min und länger kann eine Anästhesie der Bursa podotrochlearis auch schmerzhafte Prozesse im Hufgelenk betäuben (Schumacher et al 2003).…”