Rapid and reliable sedation induced by diazepam and antagonized by flumazenil in zebra finches (Taeniopygia guttata)

Protocol for inducing hippocampal formation lesions and associated behavioral testing in Japanese quail

Here, we present a protocol for inducing selective lesions in the hippocampal formation of Japanese quail (Coturnix japonica), coupled with associated behavioral testing. We first describe the surgical procedure for aspiration lesions in Japanese quail. We then detail two well-known hippocampus-dependent behavioral tests adapted to birds—foraging array (FA) and spontaneous object recognition (SOR). This protocol is adapted from those used in mammals and can be used to study the involvement of Japanese quail memory centers in declarative memory.

For complete details on the use and execution of this protocol, please refer to Damphousse et al. (2022).

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Protocol for characterizing brain function in Japanese quail (Coturnix japonica)

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Surgical procedure to create craniotomies and aspiration lesions

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Instruction for two memory tasks: foraging array and spontaneous object recognition

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Can be easily adapted to analysis of other avian species or brain regions

Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

Sedation of Wild Pyrenean Capercaillie (Tetrao urogallus aquitanicus) Using Intramuscular Midazolam

Global Positioning System (GPS) tracking offers key information in the study of movement ecology of threatened species. Nevertheless, the placement of GPS devices requires animal capture and handling, which may represent a challenge to the individual’s survival after release, mainly due to capture myopathy. The Pyrenean Capercaillie (Tetrao urogallus aquitanicus) is a threatened galliform especially sensitive to handling, extremely elusive, and challenging to capture. Our goal was to adapt a sedation protocol for Pyrenean Capercaillies undergoing GPS tagging, in order to increase their welfare and safety during the procedure. From 2018 to 2021, 23 wild Pyrenean Capercaillies were captured and sedated for GPS tagging as part of a European conservation project of emblematic Pyrenean avian species. The birds received intramuscular (IM) sedation with midazolam (ranging from 1.9 mg/kg to 8.08 mg/kg) and were handled for 20 to 40 min. Sedation was reversed with flumazenil (0.1 mg/mL IM). The sedated capercaillies were less responsive to stimuli (i.e., closed eyes and recumbency), showing discrete to no response to handling (i.e., placement of the GPS device, physical examination, cloacal temperature measurement, or reflex tests). Such response was compared in birds with sedation doses above and below the average dose (5.17 mg/kg). Only one clinical sign showed statistically significant differences between the two groups (“open-mouth breathing” sign, p = 0.02). A mortality rate of 4.35% was registered (one individual died during handling). Sedation facilitated the handling of the birds and faster interventions in the field, without increasing mortality when compared to handling without sedation. Therefore, sedation was shown to be a useful tool to reduce stress related to capture and handling of the threatened Pyrenean Capercaillie.

Avian Sedation

The use of procedural sedation in birds has become a routine practice in veterinary medicine during the past 10 years, with a corresponding increase in avian sedation research. Sedation is most often used in a clinical setting for birds to facilitate examination and/or diagnostic sample collection, splint application, grooming, and minor surgical procedures. Sedation provides several benefits over manual restraint or general anesthesia when performing clinical procedures. This review provides an overview of current studies on avian sedation and discusses common indications, protocols, and adverse effects of sedation in avian patients.

The effects of daily mitotane or diazepam treatment on the formation of chronic stress symptoms in newly captured wild house sparrows

Wild animals brought into captivity frequently experience chronic stress and typically need a period of time to adjust to the conditions of captivity (restraint, artificial lighting, altered diet, human presence, etc.), to which they may never fully acclimate. Changes in mass, the hypothalamic-pituitary-adrenal axis and heart rate parameters have been observed over the first week in newly captive house sparrows (Passer domesticus). In this study, we tested the effects of two drugs, diazepam and mitotane, in preventing the chronic stress symptoms caused by captivity, compared with oil-injected control animals. Diazepam is an anxiolytic that is widely prescribed in humans and other animals and has been shown in some cases to reduce physiological stress. Mitotane is an agent that causes chemical adrenalectomy, reducing the body's capacity to produce glucocorticoid hormones. Our mitotane treatment did not cause the expected change in corticosterone concentrations. Baseline corticosterone was higher after a week in captivity regardless of the treatment group, while stress-induced corticosterone did not significantly increase above baseline after a week in captivity in any treatment group. However, mitotane treatment did have some physiological effects, as it reduced the resting heart rate and the duration of the heart rate response to a sudden noise. It also prevented the increase in nighttime activity that we observed in control animals. There was no effect of diazepam on corticosterone, resting heart rate, activity or heart rate response to a sudden noise, and no effect of either treatment on the sympathetic vs parasympathetic control of the resting heart rate. Together, these data suggest that mitotane, but not diazepam, can have a modest impact on helping house sparrows adapt to captive conditions. Easing the transition to captivity will likely make conservation efforts, such as initiating captive breeding programs, more successful.

Blocking Opioid Receptors in a Songbird Cortical Region Modulates the Acoustic Features and Levels of Female-Directed Singing

The organization of the anterior forebrain pathway (AFP) of songbirds important for context-dependent singing is similar to that of cortical basal ganglia loops (CBG) in mammals, which underlie motor behaviors including vocalization. Since different components of the AFP express high levels of μ-opioid receptors (μ-ORs) as do CBG loops, songbirds act as model systems to study the role of opioid modulation on vocalization and the motivation to sing. The AFP in songbirds includes the cortical/pallial region LMAN (lateral magnocellular nucleus of the anterior nidopallium) which projects to Area X, a nucleus of the avian basal ganglia. In the present study, microdialysis was used to infuse different doses of the opioid antagonist naloxone in LMAN of adult male zebra finches. Whereas all doses of naloxone led to significant decreases in the number of FD (female-directed) songs, only 100 and 200 ng/ml of naloxone affected their acoustic properties. The decrease in FD song was not accompanied by changes in levels of attention toward females or those of neurotransmitters (dopamine, glutamate, and GABA) in LMAN. An earlier study had shown that similar manipulations in Area X did not lead to alterations in the number of FD songs but had significantly greater effects on their acoustic properties. Taken together, our results suggest that there are reciprocal effects of OR modulation on cortical and basal ganglia components of the AFP in songbirds.

Altering Opioid Neuromodulation in the Songbird Basal Ganglia Modulates Vocalizations

Although the interplay between endogenous opioids and dopamine (DA) in the basal ganglia (BG) is known to underlie diverse motor functions, few studies exist on their role in modulating speech and vocalization. Vocal impairment is a common symptom of Parkinson’s disease (PD), wherein DA depletion affects striosomes rich in μ-opioid receptors (μ-ORs). Symptoms of opioid addiction also include deficiencies in verbal functions and speech. To understand the interplay between the opioid system and BG in vocalization, we used adult male songbirds wherein high levels of μ-ORs are expressed in Area X, a BG region which is part of a circuit similar to the mammalian thalamocortical-basal ganglia loop. Changes in DA, glutamate and GABA levels were analyzed during the infusion of different doses of the μ-OR antagonist naloxone (50 and 100 ng/ml) specifically in Area X. Blocking μ-ORs in Area X with 100 ng/ml naloxone led to increased levels of DA in this region without altering the number of songs directed toward females (FD). Interestingly, this manipulation also led to changes in the spectro-temporal properties of FD songs, suggesting that altered opioid modulation in the thalamocortical-basal ganglia circuit can affect vocalization. Our study suggests that songbirds are excellent model systems to explore how the interplay between μ-ORs and DA modulation in the BG affects speech/vocalization.

Advancements in Evidence-Based Anesthesia of Exotic Animals

Anesthesia and sedation of pet nondomestic species are often necessary for both invasive and noninvasive procedures. Even minimally invasive procedures can be stressful for small prey species that are not domesticated or acclimated to human contact and restraint. Recent advancements in evidence-based practice will continue to improve the field based on scientifically sound best practices and rely less on anecdotal recommendations. This article focuses on new scientific literature that has been published in the past 5 years. For ease of reading, the authors divide the article to highlight advances in anesthetic pharmacology and discoveries in anesthetic physiology and monitoring.

Methylmercury Exposure Reduces the Auditory Brainstem Response of Zebra Finches (Taeniopygia guttata )

Mercury contamination from mining and fossil fuel combustion causes damage to humans and animals worldwide. Mercury exposure has been implicated in mammalian hearing impairment, but its effect on avian hearing is unknown. In this study, we examined whether lifetime dietary mercury exposure affected hearing in domestic zebra finches (Taeniopygia guttata) by studying their auditory brainstem responses (ABRs). Zebra finches exposed to mercury exhibited elevated hearing thresholds, decreased amplitudes, and longer latencies in the ABR, the first evidence of mercury-induced hearing impairment in birds. Birds are a more appropriate model for the human auditory spectrum than most mammals because of similarities in frequency discrimination, vocal learning, and communication behavior. When mercury is considered in combination with other anthropogenic stressors such as noise pollution and habitat alteration, the hearing impairments we document here could substantially degrade avian auditory communication in wild birds.