Pharmacokinetics and Effect of Intravenous Meloxicam in Weaned Holstein Calves Following Scoop Dehorning without Local Anesthesia01 December 2012
The common practice of de-horning is investigated by researchers from Iowa and Kansas State Universities. The paper focuses on the effects of using pain killers on the animal.
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, according to the research team of Johann F Coetzee, Ruby A Mosher, Butch KuKanich, Ronette Gehring, Brad Robert, J B Reinbold and Brad J White.
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.
Plasma meloxicam concentrations were detectable for 50?h post-administration and fit a 2-compartment model with a rapid distribution phase (mean T½a=0.22±0.087h) and a slower elimination phase (mean T½ß=21.86±3.03h).
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 8h (P=0.039) and 10h (P=0.044) after dehorning. Mean plasma SP concentrations were lower in meloxicam treated calves (71.36±20.84pg/mL) compared with control calves (114.70±20.84pg/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±0.13kg bodyweight/day over 10days post-dehorning compared with 0.40±0.25kg bodyweight/day in the placebo-treated calves (p=0.042).
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.
Further ReadingYou can view the full report by clicking here.