Anaesthesia of nyala (Tragelaphus angasi) with a combination of thiafentanil (A3080), medetomidine and ketamine

Validation of a LC-MS/MS method to simultaneously quantify thiafentanil and naltrexone in plasma for pharmacokinetic studies in wildlife

Thiafentanil is a popular opioid agonist that is fully reversed by administering naltrexone. This agonist-antagonist combination is administered to a wide variety of wildlife species for chemical immobilisation, however plasma concentrations for thiafentanil remain unreported. This report describes a method that was developed and validated using human plasma and cross-validated for the analysis of goat plasma. Samples were extracted using a simple protein precipitation and analysed using LC-MS/MS. The assay was validated over the calibration range 4.38 - 1120 ng/mL for thiafentanil and 15.63 - 4000 ng/mL for naltrexone. The mean inter-day accuracies for QCs prepared in human plasma (n = 18) ranged from 94.8 - 103.8 % for thiafentanil and 94.8 - 95.9 % for naltrexone with corresponding precisions of 3.4 - 7.9 % and 2.8 - 11.4 %, respectively. The mean accuracies for QCs prepared in goat plasma (n = 6) ranged from 89.0 - 100.5 % for thiafentanil and 89.0 - 98.0 % for naltrexone with the associated precisions ranging from 7.1 - 11.6 % and 4.8 - 12.3 %, respectively. Both analytes were stable on bench for six hours and for three freeze-thaw cycles. The impact of heat-inactivation, necessary for the inactivation of potential foot-and-mouth disease, on analyte stability, matrix effect and recovery were evaluated, and a correction factor was established to determine the original analyte concentrations. The method was applied to pharmacokinetic samples collected from goats. The use of goats as a model species provides the first insight into the plasma concentrations of thiafentanil.

RETROSPECTIVE COMPARISON OF FIVE DRUG PROTOCOLS FOR IMMOBILIZATION OF CAPTIVE SABLE ANTELOPE (HIPPOTRAGUS NIGER)

Sable antelope (Hippotragus niger), a large, dominant species, often require chemical immobilization for captive management. Despite several recorded protocols, limited objective or subjective data are available to guide chemical immobilization of this species. This study retrospectively compared immobilization drug combinations of carfentanil-xylazine (CX), thiafentanil-xylazine (TX), etorphine-xylazine (EX), carfentanil-acepromazine (CA), and butorphanol-azaperone-medetomidine (BAM) for healthy sable antelope at one institution. Clinically applicable physiologic measures, subjective ratings, and timing of anesthetic milestones of 161 events for 107 individuals revealed the following statistically significant findings (P < 0.05). Induction ratings were best for TX, highest degree of muscle relaxation occurred with BAM and TX, and anesthetic ratings were best for TX and EX. Time to recovery was longest and complications 2.56 times more likely with CX. Time to recumbency was shortest in TX. Heart rate was highest in CA and lowest in BAM. For immobilization procedures, this study suggests TX would be the preferred combination for H. niger. However, all drug combinations evaluated can be used successfully to immobilize H. niger, and certain combinations may be situationally preferred based on desired muscle relaxation, expected induction or recovery times, or anticipated procedure length.

The pathophysiology of rhabdomyolysis in ungulates and rats: towards the development of a rodent model of capture myopathy

Capture myopathy (CM), which is associated with the capture and translocation of wildlife, is a life-threatening condition that causes noteworthy morbidity and mortality in captured animals. Such wildlife deaths have a significant impact on nature conservation efforts and the socio-economic wellbeing of communities reliant on ecotourism. Several strategies are used to minimise the adverse consequences associated with wildlife capture, especially in ungulates, but no successful preventative or curative measures have yet been developed. The primary cause of death in wild animals diagnosed with CM stems from kidney or multiple organ failure as secondary complications to capture-induced rhabdomyolysis. Ergo, the development of accurate and robust model frameworks is vital to improve our understanding of CM. Still, since CM-related complications are borne from biological and behavioural factors that may be unique to wildlife, e.g. skeletal muscle architecture or flighty nature, certain differences between the physiology and stress responses of wildlife and rodents need consideration in such endeavours. Therefore, the purpose of this review is to summarise some of the major etiological and pathological mechanisms of the condition as it is observed in wildlife and what is currently known of CM-like syndromes, i.e. rhabdomyolysis, in laboratory rats. Additionally, we will highlight some key aspects for consideration in the development and application of potential future rodent models.

Effective thiafentanil immobilization and physiological responses of free-ranging moose (Alces alces) in northern Sweden

OBJECTIVE

To evaluate clinical and physiological responses in moose to thiafentanil administration for immobilization.

STUDY DESIGN

Cross-sectional clinical study.

ANIMALS

Eleven (six males and five females) free-ranging adult moose (Alces alces).

METHODS

Each moose was darted from a helicopter with 7.5 mg thiafentanil during March 2014 in northern Sweden. Physiological evaluation included vital signs and blood gases. Arterial blood was collected after induction and again after 10 minutes of intranasal oxygen administration and analyzed immediately with an i-STAT analyzer. A total of 10 mg naltrexone per milligram of thiafentanil was administered to all animals for reversal. Data were analyzed using descriptive statistics.

RESULTS

All moose were sufficiently immobilized with a single dart injection. Induction occurred within 3 minutes in 10 of 11 moose. One individual became recumbent while crossing a river and naltrexone was immediately administered. Animals maintained sternal recumbency with their head raised and vital signs were stable. Nine of 10 moose were hypoxemic before oxygen administration, with seven becoming markedly hypoxemic [partial pressure of arterial oxygen (PaO₂) between 40 and 59 mmHg (5.3-7.9 kPa)]. The PaO₂ increased significantly between samples, but six moose remained hypoxemic despite therapy. Hypercapnia was seen in all moose, with eight having marked hypercapnia [partial pressure of arterial carbon dioxide (PaCO₂) > 60 mmHg (>8.0 kPa)]. All moose were acidemic, with nine showing marked acidemia (pH < 7.20). The pH increased significantly with time and lactate decreased. Recoveries were rapid and uneventful, and all moose were living 6 months after capture.

CONCLUSIONS

Thiafentanil provided rapid and sufficient immobilization of moose and its effects were rapidly reversed with naltrexone. As with other opioids, moose showed hypoxemia and varying degrees of respiratory and metabolic acidosis. Arterial oxygenation of moose improved following intranasal oxygen, but hypoxemia was not fully resolved despite therapy.

CLINICAL RELEVANCE

Thiafentanil (7.5 mg per adult) is effective for immobilization of free-ranging moose. Supplemental oxygen may be of benefit when using this regimen; however, further investigation is required to confirm these results.

The use of thiafentanil oxalate and azaperone for reversible immobilisation of African buffalo (Syncerus caffer) within a nature reserve - Short communication

Although thiafentanil oxalate has been widely used for wildlife immobilisation on different species, no report has been published about its usefulness on African buffalo (Syncerus caffer). Thirty-four African buffaloes were successfully immobilised at Loskop Dam Nature Reserve, South Africa in July 2013. The animals were kept in bomas of the nature reserve. The purpose of the immobilisation was to provide opportunity for microchip implantation, ear tag placement, intradermal tuberculin test and blood sampling. All animals were immobilised with thiafentanil oxalate 6 mg/animal (0.007-0.01 mg/kg) and azaperone 40 mg/animal (0.07-0.04 mg/kg) using Dan-inject darts and gun. The opioid reversal agent naltrexone hydrochloride 60 mg/animal (0.07-0.1 mg/kg) was given intravenously to the ear vein. The mean induction time was 3.9 ± 0.2 min, the recovery time was 1.65 ± 0.87 min. The results of the present study indicate that thiafentanil oxalate, this low-volume, high-potency, reversible drug combined with azaperone provides fast induction and smooth recovery. The authors recommend this drug combination as a reliable immobilising regimen for African buffalo.