Efficacy of single-dose intravenous phenylbutazone and flunixin meglumine before, during and after exercise in an experimental reversible model of foot lameness in horses.
BACKGROUND
Objective blinded efficacy data during exercise are lacking on the use of single-dose i.v. nonsteroidal anti-inflammatory drugs (NSAIDs) before, during and after exercise.


OBJECTIVE
Single i.v. doses of either phenylbutazone (PBZ) or flunixin meglumine (FM) would prove more efficacious than negative saline control (SAL) before, during and after exercise in a reversible model of foot lameness.


METHODS
Six Quarter Horse mares had lameness induced by tightening a set screw against a heart bar shoe 1 h prior to treatment. Randomised blinded treatments included PBZ (4.4 mg/kg bwt i.v.), FM (1.1 mg/kg bwt i.v.), and SAL (1 ml/45 kg i.v.). Heart rate and lameness score (LS) were recorded at rest; every 20 min after lameness induction for 5 h and at the end of 2 min treadmill workloads of 2 and 4 m/s. Heart rate was also recorded from 0.5-60 min post exercise. Results were compared using RM ANOVA and Student-Newman-Keul's test (HR) and Wilcoxon signed rank test (%ΔLS) with significance set at P < 0.05.


RESULTS
Pre-exercise mean HR was decreased for both NSAIDs compared to SAL from 1:20-4 h post treatment (P < 0.05). Pre-exercise mean %ΔLS was decreased for PBZ (1:20-4 h) and FM (1-4 h) compared to SAL (P < 0.01). With exercise, there were no HR differences between treatments (P > 0.05), but mean %ΔLS was decreased for both NSAIDs compared to SAL (P < 0.01). Mean recovery HR was decreased for PBZ and FM from 1-60 min compared to SAL (P < 0.05).


CONCLUSIONS
PBZ and FM demonstrated definitive clinical efficacy after single i.v. doses before, during and after exercise. Use of single i.v. doses during competition may mask lameness and may affect the ability of judges in determining the soundness of horses in competition.
Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, College of Veterinary Medicine, USA. jhf@illinois.edu
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Foreman
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Grubb
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Inoue
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Banner
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D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000627:therapeutic use; D003002:Clonixin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D004334:Drug Administration Schedule; D005260:Female; D006734:Horse Diseases / Q000188:drug therapy* / Q000209:etiology; D006736:Horses; D007794:Lameness, Animal / Q000188:drug therapy*; D010653:Phenylbutazone / Q000008:administration & dosage / Q000627:therapeutic use*; D010805:Physical Conditioning, Animal; D012775:Shoes / Q000009:adverse effects
D000894:Anti-Inflammatory Agents, Non-Steroidal; C014558:flunixin meglumine; D010653:Phenylbutazone; D003002:Clonixin