ANAESTHESIA FOR ZOO ANIMALS
ANAESTHESIA FOR ZOO ANIMALS - PRIMATES
K Moriarty
Specialist Anaesthetist, Melbourne
Nearly 30 years ago a unique partnership was forged when I got a call at the Women’s Hospital from the vet at the Melbourne Zoo. Could I please help? – an elderly Primigravid orung-utan had given birth to twins 4 days earlier and was now moribund. A vet friend of mine had suggested to the zoo vet that as I was dealing with complex obstetric problems in primates all the time, I may be able to help.
So began a wonderful journey. She was so sick that I was able to put lines in, resuscitate with hartmans and haemaccel, anaesthetise her; then with the help of an obstetrician, do a manual removal. Blood cultures showed clostridium welshii septicaemia. Appropriate treatment over the next few days required re-anaesthetising, repeat infusions and massive bolus doses of penicillin and flagyl – and Girlie survived. She did not survive a subsequent pregnancy however, when veterinary academic politics did not allow the zoo vet to utilise our services and she died under anaesthetic for a retained placenta following a miscarriage.
In the beginning the equipment was absolutely primitive. The animals were anaesthetised by blow dart – literally. Ketamine was the only intramuscular drug available – and that brought interesting challenges.
There were no crushes to contain the animals, so often many shots were required because of glancing injections with unknown dose penetration. A komasaroff machine was the anaesthetic machine. A modified 4L orange juice container with the bottom cut off and padded was the mask for the large primates. No monitoring equipment, I only used oesophageal stethoscope. No warming – either of the room or the operating room table – for that matter until we begged an operating light and table from the Women’s Hospital we had neither of these either.
Prolonged recovery times from multiple doses of ketamine – some subcutaneous, some into adipose tissue and some intramuscular, with who knows how much where – were anxious times for us all.
This was a great teaching and learning time for us all. Pre-op, intra-op and especially post-op management issues were addressed with a very cooperative and ready to learn staff.
There had been a slow but dramatic evolution in induction techniques, preoperative medication and a trend to use new drugs available, in combination. We are now using small doses of reversible drugs for premed and knock-down.
The most recent fabulous advance has been the keepers programming the primates to accept hand intramuscular injections. So we have single shot, known dose, rapid knock-down, fast and easy insertion of laryngeal mask, for transport to fully equipped hospital with full monitoring, lights, O.R. table, warming, X-ray facilities and CT scanner. After transport back to their enclosure, IV reversal drugs are given when staff safety has been assured, then the patient extubated from without the cage – and the patient is sitting up with competent reflexes within 45 seconds.
It has been quite a journey and it has been such a pleasure to have been involved – especially with Helen – but also with the whole zoo family.
The ‘now’ recipe is:
- Oral alprazalam premed 1-1 ½ hours before injection;
- Zoletil – a combination of benzodiazepine, zolazepam and dissociative agent tiletamine, a ketamine derivative;
- This is combined with metatomadine. Large doses of atropine are required as anti silagogue and prevention of bradycardia;
- Maintenance is N2O/O2 and sevoflurane;
- NSAIDs are given IV intra-operatively for control of post-op pain, and orally in food after this; and
- Reversal is a combination of flumazenil, Narcan and anepamazole, again with atropine added for anti cholinergic effect
Time of Presentation
Sunday 14 May 2006 - 1030-1200
