Evaluation of long-term sedation in cheetah (Acinonyx jubatus) with perphenazine enanthate and zuclopenthixol acetate

A veterinary survey of factors associated with capture-related mortalities in cheetahs (Acinonyx jubatus)

The objective of this study was to gain better insight into factors associated with the capture-related mortality rate in cheetahs. A link to an online questionnaire was sent to zoo and wildlife veterinarians through the Species Survival Plan Programme and European Endangered Species Programme coordinators and via the 'Wildlife VetNet' Google group forum. The questionnaire consisted of 50 questions relating to the veterinarians' country of residence and experience, the medicine combinations used, standard monitoring procedures, capture-related complications and mortalities experienced in this species under different capture conditions. In addition, necropsy data from the national wildlife disease database of the National Zoological Gardens of South Africa were examined for cases where anaesthetic death was listed as the cause of death in cheetahs. A total of 75 veterinarians completed the survey, with 38 from African countries and a combined total of 37 from Europe, the United States (US) and Asia. Of these, 24% (n = 18/75) had experienced at least one capture-associated cheetah mortality, with almost all of the fatalities (29/30) reported by veterinarians working in Africa. A lack of anaesthetic monitoring and the absence of supplemental oxygen were shown to be significant risk factors for mortality. Hyperthermia, likely to be associated with capture stress, was the most common reported complication (35%). The results suggest that free-ranging rather than habituated captive cheetahs are particularly at risk of dying during immobilisation and transport. The capture-related fatalities in this species do not appear to be associated with either the veterinarian's level of clinical experience or the immobilisation agents used.

Dose-effect study of the serotonin agonist R-8-OH-DPAT on opioid-induced respiratory depression in blesbok (Damaliscus pygargus philipsi) and impala (Aepyceros melampus)

OBJECTIVE

To determine whether the R-enantiomer of 8-hydroxy-2-(di-n-propylamino) tetralin (R-8-OH-DPAT) alleviates respiratory depression in antelope species immobilized with etorphine. The experiment also aimed to establish the most clinically effective dose of this serotonin 5- HT_1A receptor agonist.

ANIMALS

A group of six female blesbok and six female impala.

STUDY DESIGN

Each animal was subjected to four immobilization treatments in a prospective four-way crossover design-control treatment consisting of only etorphine at 0.09 mg kg^-1 and three treatments consisting of etorphine at 0.09 mg kg^-1 combined with 0.005, 0.02 and 0.07 mg kg^-1 of R-8-OH-DPAT, respectively. Induction, quality of immobilization and recovery were monitored in each treatment. Physiological variables including heart rate, respiratory rate, arterial blood pressure and blood gases were measured for 35 minutes during immobilization. A linear mixed model was used to assess the effects of treatments over the recumbency period.

RESULTS

R-8-OH-DPAT did not influence induction, immobilization or recovery scores. Respiratory rate in blesbok was increased in the medium- and high-dosage R-8-OH-DPAT treatment group. However, this increased respiratory rate did not translate into improvements of arterial partial pressure of oxygen (PaO₂) values in the blesbok. The medium and higher dosages of R-8-OH-DPAT in impala led to an improved PaO₂ as well as to decreased opioid-induced tachycardia during the first 10 minutes of immobilization.

CONCLUSIONS AND CLINICAL RELEVANCE

Previous reports indicated that the racemic mixture of 8-OH-DPAT injected intravenously had a positive effect on blood-gas values in etorphine-treated hypoxemic goats. In this experiment, similar effects could be seen in impala at the higher dosage rates of R-8-OH-DPAT. However, failure to achieve an improvement of blood-gas values in blesbok was an unexpected result. It could be speculated that the dosage, species-specific differences of serotonin receptors or the use of the R-enantiomer of 8-OH-DPAT might play a role.

Long-acting neuroleptics used in wildlife management do not impair thermoregulation or physical activity in goats (Capra hircus)

Long-acting neuroleptics commonly are used in wildlife management to decrease stress-related mortality in wild animals, but with possible effects on thermoregulation, which may contribute to residual morbidity and mortality. We investigated the effects of haloperidol (0.01, 0.1, 1 mg kg(-1), n=4), zuclopenthixol (0.1, 1, 10 mg kg(-1), n=4) and perphenazine (0.1, 1, 10 mg kg(-1), n=8), as well as control injections of sunflower oil, on body temperature and physical activity of laboratory goats under hot, cold and thermoneutral ambient temperatures. Implanted data loggers continuously recorded abdominal temperature, and data loggers attached externally on the foreleg recorded movement of unrestrained goats, in a climatic chamber at 35 degrees C, 10 degrees C and 22 degrees C. Cycling ambient temperature between 35 degrees C in daytime and 10 degrees C at night time caused a significant increase in amplitude of the circadian rhythm of body temperature in goats given sunflower oil (P=0.0012, unpaired t-test, n=8), but the administration of zuclopenthixol or perphenazine did not affect this change in amplitude (P>0.05, two-way ANOVA, n=4). Mean daily body temperature after administration of zuclopenthixol or perphenazine, and mean daily activity after zuclopenthixol administration, were not significantly different to those after control injections, at any ambient temperature, for the expected duration of drug activity (all P>0.05, two-way ANOVA, n=4). Thermal response indices, and mean activity, during heat, cold or thermoneutral exposure, of goats for 7 h after haloperidol injection, were not significantly different, at any dose or any ambient temperature, to those following control injections (all P>0.05, repeated measures ANOVA, n=4). Long-acting neuroleptics did not impair activity or thermoregulation of goats subjected to inescapable thermal challenges.

Thermoregulatory, motor, behavioural, and nociceptive responses of rats to 3 long-acting neuroleptics

We investigated physiological effects of intramuscular injections of the following 3 long-acting neuroleptics commonly used in wildlife management: haloperidol (0.05, 0.1, and 0.5 mg/kg body mass), zuclopenthixol acetate (0.5, 1, and 5 mg/kg), and perphenazine enanthate (1, 3, and 10 mg/kg), in a rat model. Body temperature and cage activity were measured by intra-abdominal telemeters. Nociceptive responses were assessed by challenges to noxious heat and pressure. Haloperidol (0.5 mg/kg) produced a significant nocturnal hypothermia (p < 0.05) and decreased nighttime cage activity and food intake. Zuclopenthixol (5 mg/kg) significantly decreased nighttime body temperature and cage activity and, at 1 mg/kg and 5 mg/kg, significantly decreased food intake 5–17 h after injection (p < 0.05). Perphenazine (10 mg/kg) significantly decreased nighttime body temperature and cage activity and, at all doses, significantly decreased food intake 5–17 h after injection (p < 0.05). Significant analgesic activity was evident in rats given 5 mg/kg zuclopenthixol up to 40 h after injection, and 10 mg/kg perphenazine from 48 to 96 h after injection (p < 0.0001). Zuclopenthixol (5 mg/kg) and perphenazine (10 mg/kg) had significant antihyperalgesic activities at 16 h postinjection and 24–48 h postinjection, respectively (p < 0.0001). Haloperidol had no significant antinociceptive activity at doses tested. Motor function was impaired in rats given 0.5 mg/kg haloperidol, 5 mg/kg zuclopenthixol and 10 mg/kg perphenazine. Effects of long-acting neuroleptics on body temperature, feeding, and activity were short-lasted and should not preclude their use in wildlife. Antinociceptive actions were longer-lasting, but were nonspecific, and we recommend additional analgesics for painful procedures during wildlife management. Key words: body temperature, spontaneous activity, food intake, antinociception, motor function, long-acting neuroleptic.