Evaluation of infrared thermography as a non-invasive method of measuring the autonomic nervous response in sheep.

Eye temperature measured using infrared thermography (IRT) can be used as a non-invasive measure of autonomic nervous system (ANS) activity in cattle. The objective of this study was to evaluate if changes in eye temperature (measured using IRT) can be used to non-invasively measure ANS activity in sheep. Twenty, 2 to 4-year-old, Romney ewes were randomly assigned to receive either epinephrine (EPI) or physiological saline (SAL) for 5 min administered via jugular catheter (n = 10 ewes/treatment). Eye temperature (°C) was recorded continuously using IRT for approximately 25 min before and 20 min after the start of infusion. Heart rate and heart rate variability, measured using the root mean square of successive differences (RMSSD) and the standard deviation of all inter-beat intervals (SDNN), were recorded for 5 min before and up to 10 min after the start of infusion. Blood samples were taken before and after the infusion period to measure plasma epinephrine, norepinephrine, cortisol and packed cell volume (PCV) concentrations. During the infusion period, maximum eye temperature was on average higher (P<0.05) in sheep that received epinephrine than those that received saline. On average, heart rate was higher (SAL: 87.5 beats/min, EPI: 123.2 beats/min, SED = 7.07 beats/min; P<0.05), and RMSSD (SAL: 55.3 ms, EPI: 17.3 ms, SED = 14.18 ms) and SDNN (SAL: 54.3 ms, EPI: 21.5 ms, SED = 10.00 ms) lower (P<0.05) in ewes during the 5 min post-infusion period compared with ewes that received saline. An infusion of epinephrine resulted in higher geometric mean epinephrine (P<0.05) and cortisol (P<0.05) but not norepinephrine (P>0.05) concentrations in ewes compared to an infusion of saline. PCV concentrations were higher (P<0.001) by 7 ± 1.0% (mean±SED) in ewes after an epinephrine infusion. These results suggest that heart rate variability is a sensitive, non-invasive method that can be used to measure ANS activity in sheep, whereas change in eye temperature measured using IRT is a less sensitive method.

Effect of isoflurane alone or in combination with meloxicam on the behavior and physiology of goat kids following cautery disbudding.

Cautery disbudding of goat kids is painful, but may be alleviated with pain mitigation. We therefore evaluated the effect of administering general anesthesia (isoflurane) or a nonsteroidal anti-inflammatory drug (meloxicam) on goat kid behavior and physiology following cautery disbudding. Trial 1 (n = 12/treatment) evaluated behavioral responses in 72 female Saanen dairy goat kids (mean ± standard error of the mean; 3.9 ± 0.15 d old) and trial 2 (n = 10/treatment) evaluated physiological responses in 60 female Saanen dairy goat kids (4.3 ± 0.14 d old). Goat kids were randomly assigned to 1 of 6 treatment groups that were either (1) sham-handled only (simulated disbudding; SHAM) or disbudded with (2) no pain relief (CAUT), (3) isoflurane gas (ISO), (4) isoflurane and s.c. meloxicam combined (ISO+MEL), (5) meloxicam s.c. (0.5 mg/kg of body weight; I-MEL), or (6) oral meloxicam (0.2 mg/kg of body weight; O-MEL). Head shaking, head scratching, self-grooming, feeding, and body shaking were continuously video recorded for 24 h pre- and post-treatment. Lying behavior was recorded continuously for 24 h pre- and post-treatment using accelerometers. Plasma cortisol, glucose, and lactate concentrations were measured from blood samples collected immediately before treatment (baseline) and at 15, 60, and 120 min post-treatment. Body temperature was measured immediately after blood sampling at all blood sampling time points. Head shaking and body shaking frequencies were 50% higher in CAUT than SHAM kids 5 min post-treatment; ISO+MEL and ISO kids performed 25% less body shakes than CAUT kids. Head scratching durations 1 h post-treatment were higher in CAUT than SHAM kids, whereas O-MEL were similar to SHAM kids from 2 h post-treatment. Self-grooming, feeding, and lying did not differ between groups. Cortisol concentrations were higher in CAUT than SHAM kids (156.4 ± 26.41 and 104.1 ± 26.41 nmol/L, respectively), whereas ISO+MEL and ISO kids (88.3 ± 26.41 and 113.2 ± 26.41 nmol/L, respectively) had lower cortisol concentrations than CAUT kids over the 2-h sampling period. Moreover, O-MEL and I-MEL kids (163.0 ± 26.41 and 130.9 ± 26.41 nmol/L, respectively) had similar cortisol concentrations to CAUT kids. We found no evidence that plasma glucose and lactate concentrations or body temperature were affected by treatment. The administration of isoflurane, with or without meloxicam, appeared to reduce pain associated with cautery disbudding.