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

We hypothesised that analgesia of the navicular bursa is not selective for the navicular apparatus; and that solar pain in some horses can be temporar ily abolished or attenuated by analgesia of the navicular bursa. To test th is 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 lamen ess. The response of horses with solar pain in the dorsal or palmer aspect of th e foot to 3.5 mi local analgesic solution administered into the navicular b ursa 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 aspec t 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 mi 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-strews applied t o the dorsal margin of the sole after administration of local analgesic sol ution into the navicular bursa. In conclusion, analgesia of the navicular b ursa was Less effective in desensitising the angles of the sole than in des ensitising 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 anal gesia of the navicular bursa.