Electroencephalography during ovariohysterectomy in rats anaesthetized with halothane

Comparison of three different dosages of low-level laser therapy on expression of cell proliferation and inflammatory markers following ovariohysterectomy in rats

The objective of the current study was to evaluate Low-level laser therapy (LLLT) on the healing of incisional wounds following ovariohysterectomy in rats, by means of subjective histopathological and immunohistochemical analysis. A total of 72 female Wistar rats were categorised into four treatment groups (Group I; sacrification 4 hours following only one LLLT application, Group II; sacrification 7 days following only one LLLT application, Group III; sacrification 4 hours after two LLLT applications, and Group IV; sacrification 7 days after two LLLT applications). Each group was further divided into four different doses subgroups (Group Control [C, off mode LLLT application], L1 [1 J/cm2], L3 [3 J/cm2], and L6 [6 J/cm2]), with equal representation in each subgroup. Ovariohysterectomy was employed using two 2-cm-length midline abdominal incisions in the left and right sides of line alba. The Group C was assigned to the left side incision to each rat in the study. After irradiation, the tissue was subjected to histopathological analysis to determine the extent of mononuclear cell infiltration, edoema, and epithelialization. Additionally, immunohistochemical analysis was performed to evaluate the expression of proliferating cell nuclear antigen (pCNA) and inducible nitric oxide synthase (iNOS). Group L1 and L3 significantly decreased mononuclear cell infiltration compared with Group C in all treatment groups (p < 0.05). Group L3 significantly decreased edoema compared with Group C in all groups except for treatment Group I (p < 0.05). Group L2 and L3 significantly increased epithelization in treatment Group IV (p < 0.05). Moreover, Group L2 and L3 significantly increased pCNA in all groups, while L2 and L3 significantly decreased iNOS expression in treatment Group II, III, and IV (p < 0.05). However, no statistical difference was found between subgroups of treatment Group I in iNOS expiration (p > 0.05). The results of the current examination demonstrated that LLLT can modulate mononuclear cell infiltration and edoema, and improve epithelization, as well as increase pCNA expression, whereas decrease iNOS expression during the wound healing process, therefore enhancing wound healing following ovariohysterectomy in rats.

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.

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

REASONS FOR PERFORMING STUDY

Donkeys are believed to be less demonstrative of pain than ponies. Research into comparative sensory processing between these species is required to elucidate these behavioural differences.

OBJECTIVES

To compare changes in the electroencephalogram (EEG) recorded during castration between donkeys and ponies.

STUDY DESIGN

Prospective clinical study.

METHODS

Six ponies and 6 donkeys were castrated under halothane anaesthesia after acepromazine premedication and thiopental anaesthetic induction. Markers were inserted into the EEG recording at the time of skin incision (skin) and emasculation (emasc) for both testicles (T1 and T2) during a closed castration. Raw EEG data were analysed and the EEG variables median frequency (F50 ), total power (Ptot ) and spectral edge frequency (F95 ) derived using standard techniques. Baseline values of F50 , Ptot and F95 for each animal were used to calculate the percentage change from baseline at T1skin, T2skin, T1emasc and T2emasc.

RESULTS

Decreased F50 values relative to baseline were observed in 4 ponies and 2 donkeys across all castration time points. In the remaining animals, the F50 value increased compared with baseline. Both donkey and pony groups showed an overall decrease in Ptot values compared with baseline at T1skin, but the magnitude of the decrease was significantly less (P = 0.004) in ponies than in donkeys. Donkeys demonstrated an overall greater increase (P = 0.05) in F95 values at T1skin relative to baseline compared with ponies.

CONCLUSIONS

Electroencephalographic responses to the noxious stimulus of castration were noted in both donkeys and ponies. Donkeys demonstrated a greater change in Ptot in response to castration than ponies; thus, donkeys appear to demonstrate a cerebral cortical response to a noxious stimulus that is similar to or greater than that in ponies, suggesting that their subtle behavioural expression of pain is not due to a difference in cortical processing of noxious sensory stimuli.

Effect of alfaxalone infusion on the electroencephalogram of dogs anaesthetized with halothane

OBJECTIVE

To describe the effects of alfaxalone on the canine electroencephalogram (EEG).

STUDY DESIGN

Experimental study.

ANIMALS

Eight healthy adult Huntaway dogs.

METHODS

Anaesthesia was induced with propofol and maintained with halothane (0.85-0.95 end-tidal volume %) in oxygen. Animals were ventilated to maintain stable end-tidal CO(2) and halothane concentrations. Following a 30 minute stabilisation period, alfaxalone (0.5 mg kg(-1) ) was infused intravenously over a 5 minute period. The electroencephalogram was recorded from the beginning of the stabilisation period until 60 minutes following the start of alfaxalone treatment. Data were subjected to fast Fourier transformation, and median frequency, 95% spectral edge frequency and total EEG power were calculated. Two-factorial repeated measures anova (time and EEG channels were factors) was used for statistical analysis (p < 0.05).

RESULTS

A shift in the dominant frequency band from beta to delta after alfaxalone treatment and occasional burst suppression were observed. Median frequency decreased significantly below baseline (9.2 ± 1.4 Hz) (mean ± SD) during alfaxalone infusion. The lowest value (4.8 ± 1.2 Hz) was recorded 5 minutes after the start of infusion. Spectral edge frequency also decreased below baseline (26.2 ± 1.5 Hz) and the lowest value (22.6 ± 1.5 Hz) also was detected at 5 minutes after the start of infusion. Total EEG power did not change significantly. In some frequencies EEG power increased soon after the start of alfaxalone infusion, then decreased below baseline later (biphasic pattern).

CONCLUSIONS AND CLINICAL RELEVANCE

Alfaxalone induced biphasic changes on EEG and decreased F(50) and F(95) in halothane anaesthetized dogs.