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Anaesthesia and Surgery - Small Mammals (view source)
Revision as of 17:40, 23 August 2011
, 17:40, 23 August 2011no edit summary
'''Starving''' is not usually necessary in small mammals due to their high metabolic rate. Rabbits cannot vomit and so food does not need to be withheld. There is often food in the oropharynx of these animals, and the mouth can be flushed out before anaesthetic induction to ensure a patent airway.
'''Starving''' is not usually necessary in small mammals due to their high metabolic rate. Rabbits cannot vomit and so food does not need to be withheld. There is often food in the oropharynx of these animals, and the mouth can be flushed out before anaesthetic induction to ensure a patent airway.
'''Ferrets''' should be starved for 1-4 hours prior to surgery.
If possible, '''intravenous access''' should be obtained. In rabbits, commonly used veins include the cephalic and marginal ear veins.
<u>Preparation for surgery</u>:
<u>Preparation for surgery</u>:
'''Antiseptic fluids''' used for aseptic preparation should be '''warmed''' before use, and alcohol-based antiseptics should be avoided as they lead to excess heat loss.
'''Antiseptic fluids''' used for aseptic preparation should be '''warmed''' before use, and alcohol-based antiseptics should be avoided as they lead to excess heat loss.
The patient can be '''insulated''' using blankets, bubblewrap, and foil blankets.
Care must be taken to avoid '''hyperthermia''' as well. Electric heat pads are prone to overheating, and surgeons tend to prefer hot water bottles or incandescent lights. Operating in a warm room with additional heat from the operating light is usually enough.
Care must be taken to avoid '''hyperthermia''' as well. Electric heat pads are prone to overheating, and surgeons tend to prefer hot water bottles or incandescent lights. Operating in a warm room with additional heat from the operating light is usually enough.
:'''[[NSAIDs]]''': meloxicam, carprofen
:'''[[NSAIDs]]''': meloxicam, carprofen
:[[Local Anaesthetics|'''Local anaesthetics''']]: lidocaine, bupivicaine (low safety margin), EMLA cream for venepuncture.
:[[Local Anaesthetics|'''Local anaesthetics''']]: lidocaine, bupivicaine (low safety margin), EMLA cream for venepuncture.
Local anaesthetic blocks can be used in '''ferrets'''. Nerves commonly blocked include: infraorbital, zygomatic, mandibular, maxillary and mental. This is usually helpful for dental procedures.
'''Epidural blocks''' can also be performed in ferrets at the lumbosacral joint.
===Intubation===
===Intubation===
===Considerations during surgery===
===Considerations during surgery===
'''Position''' is important, as most small mammals have a significant weight in their abdominal viscera which may press against the diaphragm and cause breathing difficulties. They should be positioned with the '''thorax slightly above the abdomen''' to avoid this problem.
'''Position''' is important, as most small mammals have a significant weight in their abdominal viscera which may press against the diaphragm and cause breathing difficulties. They should be positioned with the '''thorax slightly above the abdomen''' to avoid this problem.
Ferrets have a '''strong vagal reflex''', making them more susceptible to development of arrhythmias and so agents should be selected to try and minimise this development.
'''Eye lubricants''' should be used to protect the eyes as they are often bulging.
'''Eye lubricants''' should be used to protect the eyes as they are often bulging.
'''Temperature monitoring''' is essential: all anaesthetics depress thermoregulation, and some cause peripheral vasodilation. Opening body cavities and removing fur removes insulation, and water loss from lungs and viscera removes heat.
'''Temperature monitoring''' is essential: all anaesthetics depress thermoregulation, and some cause peripheral vasodilation. Opening body cavities and removing fur removes insulation, and water loss from lungs and viscera removes heat.
'''Other monitoring''' equipment that can be used includes: oesophageal stethoscope, capnography, doppler.
'''Other monitoring''' equipment that can be used includes: ECG, oesophageal stethoscope, capnography, doppler.
===Anaesthetic protocols===
===Anaesthetic protocols===
'''Propofol''' can be used if an intra-venous line is available.
'''Propofol''' can be used if an intra-venous line is available.
==Post-Operative Considerations==
'''Rabbits''' should have a warm environment in which to recover to help with any hypothermia issues that may have been encountered. Artificial fleece bedding should be used then moved onto a straw/hay based bedding and not sawdust. Water should be provided and the patient should be encouraged to eat as soon as possible to help prevent '''post operative gastrointestinal issues'''. Analgesia should also be given to help prevent development of post operative ileus.
'''Rodents''' are often placed in '''incubators''' after the procedure is completed upon recovery to help maintain and increase the body temperature. This can also be aided by the use of subcutaneous or intra-peritoneal warmed fluids. Bedding should be provided such as artifical fleece or similar, but no sawdust should be used. Patients should be encouraged to eat as soon as they have fully recovered. Prokinetics may be given to guinea pigs and chinchillas to help prevent postoperative ileus. '''Non steroidal anti inflammatories''' are useful in rats also for preventing ileus. Patients should be kept '''separate from dogs and cats''' to minimise stress upon recovery.
'''Ferrets''' should be maintained on oxygen until breathing spontaneously and their circulation is stable. The ET tube should be removed when they start to move or gag. It is common for them to curl up into the sleep position during recovery and heat and blankets should be provided for burrowing during recovery. It is not uncommon postoperatively for blood pressure to drop after it appears they have recovered, particularly in upper gastrointestinal surgeries or those that have significant blood loss.
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