INTRAMUSCULAR ADMINISTRATION OF KETAMINE-MEDETOMIDINE ASSURES STABLE ANAESTHESIA NEEDED FOR LONG-TERM SURGERY IN THE ARGENTINE TEGU SALVATOR MERIANAE

Comparison of intramuscular alfaxalone with medetomidine-ketamine for inducing anaesthesia in Trachemys scripta spp. undergoing sterilization

OBJECTIVE

To compare the effect of two anaesthetic protocols on heart rate (HR), time to muscle relaxation and tracheal intubation and time to surgical plane of anaesthesia, in Trachemys scripta spp. undergoing oophorectomy.

STUDY DESIGN

Prospective randomized clinical study.

ANIMALS

A total of 43 healthy female turtles.

METHODS

Morphine (1.5 mg kg-1) was injected subcutaneously 2 hours before anaesthesia induction. The turtles were randomly administered either medetomidine (0.2 mg kg-1) and ketamine (10 mg kg-1) (group MK; n = 23) or alfaxalone (20 mg kg-1) (group A; n = 20) intramuscularly followed by bupivacaine (2 mg kg-1) administered subcutaneously along the incision site. Anaesthesia was maintained with isoflurane delivered in oxygen (100%). HR and the anaesthetic depth score (ADS) were recorded every 5 minutes from induction to recovery. A Friedman test followed by Wilcoxon tests with Bonferroni adjustment were used to compare these non-parametric data (HR and ADS) between groups and over time. Time to muscle relaxation of neck and limbs (TMR), tracheal tube insertion (TTTI) and stage of surgical anaesthesia (TADS≤3) were recorded and compared between groups using a Welch's t test after logarithmic transformation.

RESULTS

Median values of TMR, TTTI and TADS≤3 were 4, 9.5 and 25 minutes in group A, respectively, and 14, 20 and 35 minutes in group MK (TMR, TTTIp ≤ 0.0001; TADS≤3p = 0.001). Plane of anaesthesia was significantly deeper in group A than in group MK for the first 20 minutes (p < 0.01). HR at 10 and 15 minutes post injection was significantly lower in group MK (28 beats minute-1) than in group A (36 and 34 beats minute-1) (p < 0.02).

CONCLUSIONS AND CLINICAL RELEVANCE

After intramuscular injection in Trachemys scripta spp., tracheal intubation, muscle relaxation and a surgical plane of anaesthesia developed faster with alfaxalone than medetomidine-ketamine.

Sedation and Anesthesia in Exotic Animal Critical Care

Sedation and anesthesia of exotic animals in inherently challenging, but often facilitates the best care for patients. Critical illness or injury adds on another layer of complexity to their management for obtaining diagnostics and providing treatments. This article serves to review some of the more recent literature of sedation and anesthesia within exotics practice, bringing to light some nuances and considerations for when those patients are critically ill or injured.

COMPLETE UNILATERAL MAXILLECTOMY IN A COHORT OF FIVE COLOMBIAN BOAS (BOA IMPERATOR)

Five unrelated adult Colombian boas (Boa imperator) presented with a 1- to 3-mon history of unilateral rostral swelling of the maxilla associated with a chronic rubbing against the enclosure's walls. Moderate to severe gingival inflammation and ulceration of the labial mucosa were present at the level of the swelling with tenderness to the touch. Radiography revealed osteolytic or proliferative lesions of the maxillary bone. Chronic maxillary osteomyelitis was diagnosed. Unilateral maxillectomy was performed on each animal under general anesthesia. Local anesthesia was also achieved by infiltrating lidocaine along the medial and lateral aspect of the maxillary gingiva and at the level of the maxillo-ectopterygoid joint. Using a lateral gingival approach, the maxillo-prefrontal, maxillary-palatine, and maxillo-ectopterygoid attachments were transected, and the maxillary bone removed. Histologic examination revealed pyogranulomatous stomatitis and osteomyelitis in all snakes, and presence of intralesional bacteria (n = 3 snakes). Gram-negative bacteria (Chryseobacterium indologenes and Proteus mirabilis) were cultured from the resected tissue of two snakes. One snake suffered from wound dehiscence 5 d postoperatively. All snakes were fed 15 d postoperatively and ingested dead mice without apparent difficulties. One snake was examined 2 mon and 1 yr after surgery, with no evidence of soft tissue or osseous infection and only minor facial scaring; all other snakes were lost to follow-up 15 d after surgery. Unilateral maxillectomy was performed in a cohort of five Colombian boas suffering from maxillary osteomyelitis. This surgical technique should be considered as an alternative to medical treatment in boid snakes.

Partial homologies between sleep states in lizards, mammals, and birds suggest a complex evolution of sleep states in amniotes

It is crucial to determine whether rapid eye movement (REM) sleep and slow-wave sleep (SWS) (or non-REM sleep), identified in most mammals and birds, also exist in lizards, as they share a common ancestor with these groups. Recently, a study in the bearded dragon (P. vitticeps) reported states analogous to REM and SWS alternating in a surprisingly regular 80-s period, suggesting a common origin of the two sleep states across amniotes. We first confirmed these results in the bearded dragon with deep brain recordings and electro-oculogram (EOG) recordings. Then, to confirm a common origin and more finely characterize sleep in lizards, we developed a multiparametric approach in the tegu lizard, a species never recorded to date. We recorded EOG, electromyogram (EMG), heart rate, and local field potentials (LFPs) and included data on arousal thresholds, sleep deprivation, and pharmacological treatments with fluoxetine, a serotonin reuptake blocker that suppresses REM sleep in mammals. As in the bearded dragon, we demonstrate the existence of two sleep states in tegu lizards. However, no clear periodicity is apparent. The first sleep state (S1 sleep) showed high-amplitude isolated sharp waves, and the second sleep state (S2 sleep) displayed 15-Hz oscillations, isolated ocular movements, and a decrease in heart rate variability and muscle tone compared to S1. Fluoxetine treatment induced a significant decrease in S2 quantities and in the number of sharp waves in S1. Because S2 sleep is characterized by the presence of ocular movements and is inhibited by a serotonin reuptake inhibitor, as is REM sleep in birds and mammals, it might be analogous to this state. However, S2 displays a type of oscillation never previously reported and does not display a desynchronized electroencephalogram (EEG) as is observed in the bearded dragons, mammals, and birds. This suggests that the phenotype of sleep states and possibly their role can differ even between closely related species. Finally, our results suggest a common origin of two sleep states in amniotes. Yet, they also highlight a diversity of sleep phenotypes across lizards, demonstrating that the evolution of sleep states is more complex than previously thought.

Until recently, the general understanding about sleep was that only mammals and birds show two sleep states: slow-wave sleep and rapid eye movement (REM) sleep. Consequently, it was thought that these two states appeared independently in these warm-blooded animals. However, a recent paper reported the presence of these two states in the bearded dragon lizard (Pogona vitticeps), suggesting that these two states arose with the common ancestor of mammals, birds, and reptiles. We confirmed the presence of two sleep states in the bearded dragon and compared its sleep with that of another lizard, the Argentine tegu (Salvator merianae). Our results show that both lizard species have two sleep states with similarities to the two sleep states observed in mammals and birds. Additionally, our study of behavioral and physiological parameters as well as the brain activity associated with sleep in these lizards allowed us to also show important differences between these two species of lizards and between lizards, birds, and mammals. Our findings indicate that sleep in lizards is more complex than previously thought and raise further questions about the nature, function, and evolution of these two sleep states.