Use of Thiafentanil–Medetomidine for the Induction of Anesthesia in Emus (Dromaius novaehollandiae) Within a Wild Animal Park

Abstract

Fifteen adult emu (Dromaius novaehollandiae) anesthetic events were successfully undertaken with the use of thiafentanil oxalate (A3080) 0.175 mg/kg i.m. (SD 0.026) and medetomidine 0.092 mg/kg i.m. (SD 0.009) via remote injection. Following induction, the birds were transported to the clinic, where a venous blood gas sample was taken for analysis, which indicated a respiratory acidosis, with a mean arterial pCO2 of 54.46 mmHg (SD 9.31) and venous pH of 7.135 (SD 0.11), most likely due to moderate bradypnoea. Atipamezole 0.2 mg/kg i.v. (SD 0.02) was administered, immediately followed by orotracheal intubation initiating 2-3% isoflurane with 2 L/min oxygen flow. Parameters evaluated during anesthesia included heart rate, respiratory rate, anesthetic depth, and electrocardiogram readings. Physical exams plus any required procedures were performed in addition to venous blood samples for biochemistry and full blood counts. The birds were then recovered in a crate padded with grass hay with administration of 8.75 mg/kg (SD 1.36) naltrexone (50 mg/mg A3080) administered in equal doses i.v. and i.m. along with 5 mg midazolam i.m. to reduce excitement. Emus were placed in a lateral position and given 4 L/min oxygen via the endotracheal tube, until movement of the head and neck necessitated extubation. Recovery was rapid and smooth in each case with a mean time of 3.1 min from antagonist administration to sternal recovery. On the basis of rapid, smooth, and successful inductions and recoveries, the described dosage of thiafentanil and medetomidine, with administration of midazolam prior to recovery, is recommended for immobilization of adult emus. Due to evidence of respiratory acidosis and bradypnoea, careful monitoring should be instituted throughout and oxygen provision recommended from initial contact.

Chemical immobilisation and satellite tagging of free‐living southern cassowaries

“…The additional administration of diazepam caused both heart and respiration rates to decrease, which was expected because diazepam induces general depression of the central nervous system . The administration of medetomidine and isoflurane gas causes bradypnoea in ratites, resulting in respiratory acidaemia and low blood pH, which lead to further complications and require manual ventilation or supplementary oxygen . As veterinary support and supplies are often limited in the field, we argue that an anaesthetic that does not induce bradypnoea is preferable when anaesthetising large ratites not in captivity.…”

“…Medetomidine has been shown to provide satisfactory sedation of captive southern cassowaries and emus ( Dromaius novaehollandiae ) and with the aid of the reversal agent, atipamezole, the birds recovered without the violent recovery and convulsions that accompanied other commonly used sedatives . Those findings surmise medetomidine to be the ideal drug for the chemical restraint of large ratites, but initial trials conducted by us showed that medetomidine was ineffective for wild southern cassowaries, because the long induction time (∼15 min) did not provide a suitable level of chemical immobilisation before the birds fled into the thick rainforest.…”

“…Moreover, excessive struggling or excitement may also cause fractured limbs, haemorrhaging and death of the bird. Chemical restraint is usually desirable when handling larger ratites and a range of anaesthetics have been trialled with varying degrees of success …”

“…The main concern with chemical immobilisation is the risk of self‐trauma to the bird or injury to handlers during the knock‐out and recovery phases . The majority of studies on the chemical restraint of large ratites have been conducted in ostriches ( Struthio camelus ), with the protocols being transferred to other species, with broadly similar results . The drugs that have been used include ketamine hydrochloride on its own or in combination with xylazine, diazepam or alphaxalone; a mixture of zolazepam and tiletamine; etorphine; butorphanol; medetomidine; and thiafentanil–dexmedetomidine …”

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

“…Thiafentanil has been widely used for wildlife immobilisation on different species: nyala (Cooper et al, 2005), Lichtenstein's hartebeest (Citino et al, 2002), mule deer (Wolfe et al, 2004), emu (Cushing and McClean, 2010), Tibetan yak (Cushing et al, 2011), gaur (Napier et al, 2011), axis deer (Smith et al, 2006) and greater rhea (Ter Beest et al, 2012). The thiafentanil-azaperone combination for African buffalo (Syncerus caffer) immobilisation has been mentioned in books (Kreeger et al, 2002;West et al, 2008).…”