title: Is anaesthesia of the deep branch of the lateral plantar nerve specific for the diagnosis of proximal metatarsal pain in the horse?
abstract: OBJECTIVE
  To investigate the specificity of anaesthesia of the deep branch of the lateral plantar nerve (DB-LPN).
  
  
  METHODS
  Twenty horses had DB-LPN anaesthesia performed by a single injection technique as part of a lameness investigation. The mechanical nociceptive threshold (NT) was measured using a handheld force meter at six points on the lateral aspect of the limb: before diagnostic anaesthesia (T0), and at 15 (T15) and 30 (T30) minutes post anaesthesia. Paired t-tests were performed and significance was set at p <0.05. In addition, ten cadaveric limbs were injected with 2.5 ml new methylene blue solution using a single injection technique to evaluate the extent of dye diffusion within the proximal metatarsal region.
  
  
  RESULTS
  Compared with T0, there was a significant decrease in NT for all points combined at T15 (p = 0.008) and also at T30 (p = 0.007). There was a significant decrease in NT at T15 on the lateral third metatarsal bone (p = 0.012). At T30 there was a significant decrease in NT at the lateral sesamoid (p = 0.007), lateral third metatarsal bone (p = 0.031), and mid metatarsus (p = 0.033). Four out of 20 horses had a NT greater than 10 N at the lateral heel bulb at T30. In the cadaveric limbs, the total diffusion distance for all limbs (mean ± SD) was 70.4 ± 20.5 mm. Dye surrounded the DB-LPN in all limbs and the lateral plantar nerve (LPN) in nine out of 10 limbs.
  
  
  CONCLUSIONS
  Concurrent anaesthesia of the LPN is likely to occur when DB-LPN anaesthesia is performed using a single injection technique.
authors.affiliation: Dr. G. Hinnigan, Dalehead Veterinary Group, Station Road, Settle, North Yorkshire, BD24 9AA, United Kingdom, Phone: +44 7966 244795, Fax: +441729825171, E-mail: guyhin2@hotmail.com.
authors.forename: G
authors.initials: G
authors.lastname: Hinnigan
authors.forename: P
authors.initials: P
authors.lastname: Milner
authors.forename: A
authors.initials: A
authors.lastname: Talbot
authors.forename: E
authors.initials: E
authors.lastname: Singer
mesh_terms: D000772:Anesthesia, Local / Q000662:veterinary*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D002102:Cadaver; D004396:Coloring Agents; D005260:Female; D006614:Hindlimb / Q000473:pathology; D006734:Horse Diseases / Q000175:diagnosis*; D006736:Horses; D007267:Injections; D008297:Male; D008619:Mepivacaine / Q000008:administration & dosage / Q000494:pharmacology*; D008684:Metatarsus / Q000473:pathology*; D009407:Nerve Block / Q000379:methods*; D010146:Pain / Q000175:diagnosis / Q000662:veterinary*; D010147:Pain Measurement / Q000662:veterinary
chemical_list: D000779:Anesthetics, Local; D004396:Coloring Agents; D008619:Mepivacaine
keywords: Horse; diagnostic anaesthesia; lameness; nociception; proximal suspensory desmitis