title: Pharmacokinetics and effect of intravenous meloxicam in weaned Holstein calves following scoop dehorning without local anesthesia.
abstract: BACKGROUND
  Dehorning is a common practice involving calves on dairy operations in the United States. However, less than 20% of producers report using analgesics or anesthetics during dehorning. Administration of a systemic analgesic drug at the time of dehorning may be attractive to dairy producers since cornual nerve blocks require 10 - 15 min to take effect and only provide pain relief for a few hours. The primary objectives of this trial were to (1) describe the compartmental pharmacokinetics of meloxicam in calves after IV administration at 0.5 mg/kg and (2) to determine the effect of meloxicam (n = 6) or placebo (n = 6) treatment on serum cortisol response, plasma substance P (SP) concentrations, heart rate (HR), activity and weight gain in calves after scoop dehorning and thermocautery without local anesthesia.
  
  
  RESULTS
  Plasma meloxicam concentrations were detectable for 50 h post-administration and fit a 2-compartment model with a rapid distribution phase (mean T(1/2α) = 0.22 ± 0.087 h) and a slower elimination phase (mean T(1/2β) = 21.86 ± 3.03 h). Dehorning caused a significant increase in serum cortisol concentrations and HR (P < 0.05). HR was significantly lower in the meloxicam-treated calves compared with placebo-treated calves at 8 h (P = 0.039) and 10 h (P = 0.044) after dehorning. Mean plasma SP concentrations were lower in meloxicam treated calves (71.36 ± 20.84 pg/mL) compared with control calves (114.70 ± 20.84 pg/mL) (P = 0.038). Furthermore, the change in plasma SP from baseline was inversely proportional to corresponding plasma meloxicam concentrations (P = 0.008). The effect of dehorning on lying behavior was less significant in meloxicam-treated calves (p = 0.40) compared to the placebo-treated calves (P < 0.01). Calves receiving meloxicam prior to dehorning gained on average 1.05 ± 0.13 kg bodyweight/day over 10 days post-dehorning compared with 0.40 ± 0.25 kg bodyweight/day in the placebo-treated calves (p = 0.042).
  
  
  CONCLUSIONS
  To our knowledge, this is the first published report examining the effects of meloxicam without local anesthesia on SP, activity and performance of calves post-dehorning. These findings suggest that administration of meloxicam alone immediately prior to dehorning does not mitigate signs of acute distress but may have long term physiological, behavior and performance effects.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506-5601, USA. hcoetzee@iastate.edu
authors.forename: Johann F
authors.initials: JF
authors.lastname: Coetzee
authors.forename: Ruby A
authors.initials: RA
authors.lastname: Mosher
authors.forename: Butch
authors.initials: B
authors.lastname: KuKanich
authors.forename: Ronette
authors.initials: R
authors.lastname: Gehring
authors.forename: Brad
authors.initials: B
authors.lastname: Robert
authors.forename: J Brandon
authors.initials: JB
authors.lastname: Reinbold
authors.forename: Brad J
authors.initials: BJ
authors.lastname: White
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy*; D006339:Heart Rate / Q000187:drug effects; D006733:Horns / Q000601:surgery*; D006854:Hydrocortisone / Q000097:blood; D000077239:Meloxicam; D010146:Pain / Q000188:drug therapy / Q000662:veterinary*; D013373:Substance P / Q000097:blood; D013843:Thiazines / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D013844:Thiazoles / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D015430:Weight Gain / Q000187:drug effects
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D013843:Thiazines; D013844:Thiazoles; D013373:Substance P; D000077239:Meloxicam; D006854:Hydrocortisone