Spontaneous electroencephalographic changes in a castration model as an indicator of nociception: a comparison between donkeys and ponies

Physiological and electroencephalogram responses in goats subjected to pre-and during slaughter stress

A comprehensive stress assessment is vital in understanding the impact of the pre-slaughter procedure on animal welfare. The transportation and handling process was commonly reported to cause stress in animals. This research utilises electroencephalography (EEG) as an alternative stress indicator to non-painful acute stress measurement. EEG has been proved to be instantaneous and sensitive with specific results. Therefore, this study was aimed to determine the stress level of goats subjected to two different transportation duration and the effect of lairage based on their EEG activities and blood parameters changes. Eighteen adult male goats were divided into two transportation stress groups based on the transport duration: the two-hour (TS2) and six-hour (TS6) groups. Then, each group was then again divided into three smaller groups according to the lairage duration, which was three-hour (L3), six-hour (L6), and overnight (L12) groups. Blood was sampled before transport, after transport, and during slaughter while EEG was recorded before transport, after transport, after lairage, and during slaughter. Results revealed that there was a significant decrease in beta wave activity compared to baseline in TS2 goats (P < 0.05) after transportation, whereas no significant difference was detected in the TS6 goats. At the same time, goats from the TS2 group showed increase in creatine kinase (CK) and lactate dehydrogenase (LDH) compared to that in TS6 goats. Together with the observed cortisol concentration, these findings showed that the TS6 goats were fully adapted to the transportation stress while the TS2 goats were still under stress. As for the lairage duration, it was observed that the TS2L3 goats showed lower EEG activities than the values obtained after two-hour transportation, while lower EEG activities were found from the TS6L6 goats after six-hour transportation. Therefore, it can be concluded that three-hour lairage was adequate to lower the impact of two hours transportation stress, whereas six-hour lairage was required to reduce the impact of six hours transportation stress. Finally, it was also found that the TS6L3, TS6L6, and TS6L12 groups took a long time to die after slaughter than the TS2L3, TS2L6, and TS2L12 goats based on the time their EEG activity reached isoelectric.

Development of a Donkey Grimace Scale to Recognize Pain in Donkeys (Equus asinus) Post Castration

The objectives of this study were to establish a donkey ethogram, followed by a donkey grimace scale to be applied to donkeys pre- and post-castration and to test if there was a notable difference in scores based on observer knowledge, gender, and experience, which could reveal possible discomfort/pain. Nine healthy male adult donkeys were surgically castrated. Fifty-four photos were selected from frontal, lateral, and body views taken pre- and post-castration. Observers ranging from minimal to extensive knowledge and levels of experience based on education and hours/month spent with donkeys scored six photos/donkey on a scale of 0-2 (0 = not present, 1 = moderately present, 2 = obviously present). Scores were based on body language and facial parameters: Ears down, ears back, eye white showing, glazed look, orbital tightening, eyes round shape, nostril tension, eyes narrow shape, muzzle tension, and abnormal stance and overall perception of the animal being in pain. Level of experience and knowledge, as well as gender significantly (p < 0.001), affected observers' ability to accurately score images. The study suggests that the most significant indicators of pain in donkeys are overall appearance and abnormal body stance provided their sensitivity, specificity and accuracy values of 63.18%, 62.07%, and 62.60%, respectively.

Post-operative pain behaviour associated with surgical castration in donkeys (Equus asinus)

Background

Recognising pain in donkeys is challenging because they are stoic.

Objectives

To identify the responses of donkeys before and after surgical pain.

Study design

Prospective, short‐term longitudinal pre‐ and post‐intervention observations.

Methods

Forty adult donkeys underwent surgical castration after sedation with intravenous (IV) xylazine, induction with guaiphenesin/thiopental IV and maintenance of anaesthesia with isoflurane and local anaesthetic blockade. Four hours after recovery from anaesthesia, flunixin meglumine 1.1 mg/kg, dipyrone 10 mg/kg and morphine 0.2 mg/kg IV were administered. Behavioural responses exhibited by the animals housed in individual stalls were recorded in four 30‐min videos: before castration (M0), and 3.5‐4.0 hours (M1), 5.5‐6.0 hours (M2) and 23.5‐24.0 hours after recovery from anaesthesia (M3). To exclude the influence of insects, the behaviour of six apparently pain‐free donkeys was compared with and without the presence of faeces and urine in the stall.

Results

When compared with presurgical baseline behaviours (M0), after surgery (M1) donkeys raised their pelvic limbs more (P = .003). When compared with M1, after analgesia (M2), the median frequencies of ear movements (44 vs 16; P < .001), head shaking (7 vs 1; P < .001), head turning (5 vs 0; P < .001) and lifting of the both limbs (7 vs 0; P = .008) decreased; feeding (0 vs 29; P < .001) and water intake (0 vs 0, range 0‐1 vs 0‐7; P = .05) increased. The dirty stall increased tail (53 vs 80; P = .03), head (16 vs 30; P = .03) and ear movements (50 vs 78; P = .04).

Main limitations

The dirty stall and presence of insects possibly contributed to the expression of behaviours unrelated to pain.

Conclusion

Lifting the pelvic limbs was the only specific pain behaviour after castration in donkeys. Analgesia restored appetite and water intake and reduced the frequency of head shaking and turning, ear movement and lifting the limbs. Tail, head and ear movements are unspecific responses related both to pain and a dirty stall, and are confounding factors when pain is assessed in donkeys in the presence of insects.

Anesthesia, Sedation, and Pain Management of Donkeys and Mules

The number of donkeys in the world may not be increasing but awareness of their use and concern for welfare and pain recognition and treatment are receiving increasing veterinary interest. Therefore, accurate information about anesthesia and analgesia in donkeys and mules is important to more equine practitioners. This review highlights the current knowledge on various anesthetic and analgesic approaches in donkey and mules. The authors emphasize that there is still much information that is not available about donkeys and mules; in many circumstances, the clinician must use available equine information to treat the patient, while monitoring for differences in response.

Mitigation of electroencephalographic and cardiovascular responses to castration in Bos indicus bulls following the administration of either lidocaine or meloxicam

OBJECTIVE

To investigate the mitigating effects of administration of local anaesthetic or systemic meloxicam on the electroencephalographic (EEG) and cardiovascular responses during surgical castration of Bos indicus bull calves.

STUDY DESIGN

Prospective, randomized, experimental study.

ANIMALS

Thirty-six 6-8 month-old Bos indicus bull calves, with a mean ± standard deviation weight of 237 ± 19 kg.

METHODS

Animals were allocated randomly to three groups of 12 (group L, 260 mg of 2% lidocaine subcutaneously and intratesticularly 5 minutes prior to castration; group M, 0.5 mg kg^-1 of meloxicam subcutaneously 30 minutes prior to castration; group C, no preoperative analgesia administered). Anaesthesia was induced and maintained with halothane (0.9-1.1%) in oxygen. Electroencephalogram, heart rate (HR) and mean blood pressure (MAP) were recorded for 300 seconds prior to (baseline, B) and from the start of surgery (first testicle removal, T1). HR and MAP were compared at 10 second intervals for 90 seconds from the start of T1. Median frequency (F₅₀), spectral edge frequency (F₉₅) and total power of the EEG (P_tot) were analysed using area under the curve comparing T1 to B.

RESULTS

All EEG variables were significantly different between B and T1 (p ≤ 0.0001). No differences in F₅₀ were found between groups during T1 (p = 0.6491). F₉₅ and P_tot were significantly different between group L and groups C and M during T1 (p = 0.0005 and 0.0163, respectively). There were transient significant changes in HR and MAP in groups L and M compared to group C during the 20-50 second periods.

CONCLUSIONS

The EEG changes indicate nociceptive responses in all three groups during surgical castration, greater in group L compared to groups C and M. Both analgesics attenuated the peracute cardiovascular response. Lidocaine and meloxicam administered prior to castration attenuated these responses in Bos indicus bull calves.

CLINICAL RELEVANCE

These findings provide support for the preoperative administration of lidocaine and potentially meloxicam for castration in Bos indicus bull calves.

An Ambulatory Electroencephalography System for Freely Moving Horses: An Innovating Approach

Electroencephalography (EEG) that has been extensively studied in humans presents also a large interest for studies on animal brain processes. However, since the quality of the recordings is altered by muscular activity, most EEG recordings on animals are obtained using invasive methods with deeply implanted electrodes. This requires anesthesia and can thus only be used in laboratory or clinical settings. As EEG is a very useful tool both for detecting brain alterations due to diseases or accidents and to evaluate the arousal and attentional state of the animal, it seemed crucial to develop a tool that would make such recordings possible in the horse’s home environment, with a freely moving horse. Such a tool should neither be invasive nor cause discomforts to the horse as the usual other practice which consists, after shaving the zone, in gluing the electrodes to the skin. To fulfill these requirements, we developed a novel EEG headset adapted to the horse’s head that allows an easy and fast positioning of the electrodes and that can be used in the home environment on a freely moving horse. In this study, we show that this EEG headset allows to obtain reliable recordings, and we propose an original evaluation of an animal’s “EEG profile” that allows comparisons between individuals and situations. This EEG headset opens new possibilities of investigation on horse cognition, and it can also become a useful tool for veterinarians to evaluate cerebral disorders or check the anesthesia level during a surgery.