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Repeated anaesthesia in an Okapi (Okapia johnstoni)
Letters to the Editor
Repeated anaesthesia in an Okapi (Okapia johnstoni)
We wish to report a series of anaesthetics in an okapi. The okapi is an artiodactylid mammal of the family giraffidae, native to African forest habitats. There are approximately 160 captive okapi worldwide. Complications associated with anaesthesia have been stated to be the most important cause of death in adult captive okapi (Leus & Van Puijenbroeck 1995). However little published information exists on this subject. A captive male okapi, estimated weight 250 kg, was anaesthetized on eight occasions (over a 42 month period) for foot trimming and related procedures. He was seven years old at the first anaesthetic and otherwise healthy. Food was withheld for 18 hours and water for 12 hours before anaesthesia. Immediately before induction of anaesthesia the okapi was guided into a straw bedded pen, with walls also padded with straw. Initial immobization was with 20 mg medetomidine (Zalopine, Orion Pharma, Finland) and 500 mg ketamine (Ketaset, Fort Dodge Animal Health, UK) administered as an intramuscular (IM) injection by dart. If the response was inadequate (i.e. the okapi was not recumbent) further IM injection(s) (by dart) of medetomidine and ketamine were administered as required (5– 10 mg and 200–300 mg respectively). Once recumbency was achieved, and the animal did not respond to external stimuli, an intravenous (IV) catheter (20 gauge) was placed in an auricular vein. Ketamine (200–300 mg) was administered via the catheter to complete induction of anaesthesia. A 16 mm internal diameter endotracheal tube (ETT) was placed using manual guidance, and the cuff inflated immediately. The cranial part of the neck of the okapi was raised to maintain a posture in which the thoracic inlet and nostrils were both at a level below that of the poll. Anaesthesia was maintained using isoflurane delivered in oxygen via a circle breathing system. Long tubing permitted the machine and equipment to be distant from the animal. Depth of anaesthesia was assessed using palpebral reflexes, eye position, jaw tone, respiratory rate and heart rate. Non-steroidal anti-inflammatory agents (carprofen 350 mg (Rimadyl Small Animal Solution
for Injection 50 mg mL)1 Pfizer Animal Health, UK) or meloxicam 50–75 mg (Metacam 20 mg mL)1 Solution for Injection for cattle, pigs and horses, Boehringer Ingelheim, UK)) were administered IV and antibiotics if required. At the end of anaesthesia, the okapi was rolled into sternal recumbency in a suitable position to allow it stand. Atipamezole (Antisedan 5 mg mL)1 solution for injection, Elanco Animal Health, UK) 50 mg IM and 25 mg IV) was administered. As the respiratory rate increased, the circle system was disconnected and the IV catheter removed. The ETT was not removed until swallowing was seen. After this, personnel left the area, permitting the okapi to recover in the dimly lit, quiet pen, under constant observation. Additional sedation achieved by further ‘top-ups’ with medetomidine and ketamine was required in five out of eight anaesthetics, resulting in a mean ± SD dose to produce recumbency of 25 ± 5 mg medetomidine and 693 ± 219) mg ketamine. On one occasion, where several dart failures resulted in uncertainty in drug dose received, several ‘top-ups’ were required. This occasion has been omitted from dose and time to recumbency data. Recumbency was achieved in 25 (13) minutes from first dart. Respiratory rate was 63 (12) breaths minute)1. and pulse rate 61(7) beats minute)1. Isoflurane vaporiser setting was 1.2 (0.8). Capnography was available on three occasions; on these mean end-tidal carbon dioxide was 7.1 (1.3) kPa (53.3 ± 9.8 mmHg). Time from disconnection of the breathing system to standing was 6 (4) minutes. Efficacy of darting may be affected by a number of factors including the dart position, local blood flow and the pressure injecting the dart contents. Although ‘top-up’ darts were required on some occasions, it was decided not to increase the doses used for the next occasion as the administration system may have been as much a reason for failure as the dose used. On some occasions (presumably when administration conditions were more favourable) a single dose produced the required effect whilst on others the same dose was inadequate and ‘top-ups’ were requried. In this series there was a tendency for the effect from darting of anaesthetics
Ó 2012 The Authors. Veterinary Anaesthesia and Analgesia Ó 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists, 39, 446–450
449
Letters to the Editor
to decrease, which may be related to muscle fibrosis altering uptake, or to an altered drug response. These doses have been used subsequently in a different individual okapi with good results from a single dart (unreported data). As for all large animals, injury during induction or recovery is a risk. The pen was padded to minimise this risk. Manual assistance to achieve recumbency during induction and to stand in recovery have been recommended (Citino & Bush 2007). However these animals are not domesticated and may be unfamiliar with close handling. Recoveries were generally calm in this okapi. None were assisted and no injuries ensued. Regurgitation and aspiration are observed frequently (personal communication cited in Citino & Bush 2007). In this series of anaesthetics, regurgitation was observed in three of the eight procedures, although always when the ETT was in position. When regurgitation occurred, as much material as possible was flushed from the mouth and oesophagus with saline. The ETT was removed on one occasion with the cuff partly inflated to remove material from the trachea. However this procedure risks laryngeal damage. Regurgitation is common in other ruminant type herbivorous animals, in both the very light or deeply anaesthetized animal. The major anaesthetic complication noted was hypoventilation. Similar to a giraffe (Williams et al. 2007), thoracic compliance appeared poor and expansion restricted. Blood gas analysis was available only on one occasion, and only a single sample was analysed but hypercapnia was marked (11.6 kPa, 87 mmHg). Rapid shallow ventilation was always observed and ventilation was assisted manually in an attempt to minimise the increase in carbon dioxide. Apnoea has been reported after repeating medetomidine-ketamine injection in giraffes (Flach et al. 2002) but was not observed in this okapi.
450
In conclusion, although presenting challenges for the anaesthetist, including difficulty with drug delivery and possible ‘top-up’ requirement, anaesthesia in this okapi was successfully achieved on eight occasions.
Acknowledgement The authors would like to thank Angharad SimlettMoss for her help in data collation for this report. PJ Murison*, A Jones* & S Redrobe *Department of Clinical Veterinary Science, University of Bristol, Langford, Bristol, UK Veterinary Department, Bristol Zoo Gardens, Bristol, UK E-mail: [email protected] References Citino SB, Bush M (2007) Giraffidae. In: Zoo Animal and Wildlife Immobilization and Anesthesia. West G, Heard D, Caulkett N (eds.). Blackwell publishing, IA, USA. pp. 595– 605. Flach EJ, Taylor PM, Sainsbury AW et al. (2002) Immobilisation of giraffe with medetomidine and ketamine followed by gaseous anaesthesia. Proceedings of the European Association of Zoo- and Wildlife Veterinarians (EAZWV) 4th scientific meeting, Heidelberg, Germany pp. 191–197 Leus K, Van Puijenbroeck B (1995) Okapi (Okapia johnstoni) International Studbook, Royal Zoological Society of Antwerp, Antwerp, Belgium. Williams DG, Murison PJ, Hill CL (2007) Dystocia in a Rothschild giraffe leading to a caesarean section. J Vet Med Ser A 54, 9–202. Received 13 July 2011; accepted 19 October 2011. doi:10.1111/j.1467-2995.2012.00738.x
Ó 2012 The Authors. Veterinary Anaesthesia and Analgesia Ó 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists, 39, 446–450
Repeated anaesthesia in an Okapi (Okapia johnstoni)
We wish to report a series of anaesthetics in an okapi. The okapi is an artiodactylid mammal of the family giraffidae, native to African forest habitats. There are approximately 160 captive okapi worldwide. Complications associated with anaesthesia have been stated to be the most important cause of death in adult captive okapi (Leus & Van Puijenbroeck 1995). However little published information exists on this subject. A captive male okapi, estimated weight 250 kg, was anaesthetized on eight occasions (over a 42 month period) for foot trimming and related procedures. He was seven years old at the first anaesthetic and otherwise healthy. Food was withheld for 18 hours and water for 12 hours before anaesthesia. Immediately before induction of anaesthesia the okapi was guided into a straw bedded pen, with walls also padded with straw. Initial immobization was with 20 mg medetomidine (Zalopine, Orion Pharma, Finland) and 500 mg ketamine (Ketaset, Fort Dodge Animal Health, UK) administered as an intramuscular (IM) injection by dart. If the response was inadequate (i.e. the okapi was not recumbent) further IM injection(s) (by dart) of medetomidine and ketamine were administered as required (5– 10 mg and 200–300 mg respectively). Once recumbency was achieved, and the animal did not respond to external stimuli, an intravenous (IV) catheter (20 gauge) was placed in an auricular vein. Ketamine (200–300 mg) was administered via the catheter to complete induction of anaesthesia. A 16 mm internal diameter endotracheal tube (ETT) was placed using manual guidance, and the cuff inflated immediately. The cranial part of the neck of the okapi was raised to maintain a posture in which the thoracic inlet and nostrils were both at a level below that of the poll. Anaesthesia was maintained using isoflurane delivered in oxygen via a circle breathing system. Long tubing permitted the machine and equipment to be distant from the animal. Depth of anaesthesia was assessed using palpebral reflexes, eye position, jaw tone, respiratory rate and heart rate. Non-steroidal anti-inflammatory agents (carprofen 350 mg (Rimadyl Small Animal Solution
for Injection 50 mg mL)1 Pfizer Animal Health, UK) or meloxicam 50–75 mg (Metacam 20 mg mL)1 Solution for Injection for cattle, pigs and horses, Boehringer Ingelheim, UK)) were administered IV and antibiotics if required. At the end of anaesthesia, the okapi was rolled into sternal recumbency in a suitable position to allow it stand. Atipamezole (Antisedan 5 mg mL)1 solution for injection, Elanco Animal Health, UK) 50 mg IM and 25 mg IV) was administered. As the respiratory rate increased, the circle system was disconnected and the IV catheter removed. The ETT was not removed until swallowing was seen. After this, personnel left the area, permitting the okapi to recover in the dimly lit, quiet pen, under constant observation. Additional sedation achieved by further ‘top-ups’ with medetomidine and ketamine was required in five out of eight anaesthetics, resulting in a mean ± SD dose to produce recumbency of 25 ± 5 mg medetomidine and 693 ± 219) mg ketamine. On one occasion, where several dart failures resulted in uncertainty in drug dose received, several ‘top-ups’ were required. This occasion has been omitted from dose and time to recumbency data. Recumbency was achieved in 25 (13) minutes from first dart. Respiratory rate was 63 (12) breaths minute)1. and pulse rate 61(7) beats minute)1. Isoflurane vaporiser setting was 1.2 (0.8). Capnography was available on three occasions; on these mean end-tidal carbon dioxide was 7.1 (1.3) kPa (53.3 ± 9.8 mmHg). Time from disconnection of the breathing system to standing was 6 (4) minutes. Efficacy of darting may be affected by a number of factors including the dart position, local blood flow and the pressure injecting the dart contents. Although ‘top-up’ darts were required on some occasions, it was decided not to increase the doses used for the next occasion as the administration system may have been as much a reason for failure as the dose used. On some occasions (presumably when administration conditions were more favourable) a single dose produced the required effect whilst on others the same dose was inadequate and ‘top-ups’ were requried. In this series there was a tendency for the effect from darting of anaesthetics
Ó 2012 The Authors. Veterinary Anaesthesia and Analgesia Ó 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists, 39, 446–450
449
Letters to the Editor
to decrease, which may be related to muscle fibrosis altering uptake, or to an altered drug response. These doses have been used subsequently in a different individual okapi with good results from a single dart (unreported data). As for all large animals, injury during induction or recovery is a risk. The pen was padded to minimise this risk. Manual assistance to achieve recumbency during induction and to stand in recovery have been recommended (Citino & Bush 2007). However these animals are not domesticated and may be unfamiliar with close handling. Recoveries were generally calm in this okapi. None were assisted and no injuries ensued. Regurgitation and aspiration are observed frequently (personal communication cited in Citino & Bush 2007). In this series of anaesthetics, regurgitation was observed in three of the eight procedures, although always when the ETT was in position. When regurgitation occurred, as much material as possible was flushed from the mouth and oesophagus with saline. The ETT was removed on one occasion with the cuff partly inflated to remove material from the trachea. However this procedure risks laryngeal damage. Regurgitation is common in other ruminant type herbivorous animals, in both the very light or deeply anaesthetized animal. The major anaesthetic complication noted was hypoventilation. Similar to a giraffe (Williams et al. 2007), thoracic compliance appeared poor and expansion restricted. Blood gas analysis was available only on one occasion, and only a single sample was analysed but hypercapnia was marked (11.6 kPa, 87 mmHg). Rapid shallow ventilation was always observed and ventilation was assisted manually in an attempt to minimise the increase in carbon dioxide. Apnoea has been reported after repeating medetomidine-ketamine injection in giraffes (Flach et al. 2002) but was not observed in this okapi.
450
In conclusion, although presenting challenges for the anaesthetist, including difficulty with drug delivery and possible ‘top-up’ requirement, anaesthesia in this okapi was successfully achieved on eight occasions.
Acknowledgement The authors would like to thank Angharad SimlettMoss for her help in data collation for this report. PJ Murison*, A Jones* & S Redrobe *Department of Clinical Veterinary Science, University of Bristol, Langford, Bristol, UK Veterinary Department, Bristol Zoo Gardens, Bristol, UK E-mail: [email protected] References Citino SB, Bush M (2007) Giraffidae. In: Zoo Animal and Wildlife Immobilization and Anesthesia. West G, Heard D, Caulkett N (eds.). Blackwell publishing, IA, USA. pp. 595– 605. Flach EJ, Taylor PM, Sainsbury AW et al. (2002) Immobilisation of giraffe with medetomidine and ketamine followed by gaseous anaesthesia. Proceedings of the European Association of Zoo- and Wildlife Veterinarians (EAZWV) 4th scientific meeting, Heidelberg, Germany pp. 191–197 Leus K, Van Puijenbroeck B (1995) Okapi (Okapia johnstoni) International Studbook, Royal Zoological Society of Antwerp, Antwerp, Belgium. Williams DG, Murison PJ, Hill CL (2007) Dystocia in a Rothschild giraffe leading to a caesarean section. J Vet Med Ser A 54, 9–202. Received 13 July 2011; accepted 19 October 2011. doi:10.1111/j.1467-2995.2012.00738.x
Ó 2012 The Authors. Veterinary Anaesthesia and Analgesia Ó 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists, 39, 446–450