In his talk entitled “Basic surgical techniques in birds”, Neil Forbes rose to the challenge of condensing his breadth of experience into a stimulating, fast-paced presentation on 8 February.
Neil began by noting that all surgeries commonly conducted in other companion animals can be done in birds. “There are differences of course – a lot of our patients are smaller… My best record is a successful caesarean on a 26g lizard.” With maximum blood loss of 1 percent body weight, loss of 0.3ml to 0.7ml blood could be fatal for a budgie, Neil said, emphasising that surgery must be more delicate and precise in birds.
Because birds hide signs of illness, they also tend to be in a worse condition than other animals by the time they enter the practice. “We should assume that all traumatised or sick patients are suffering from shock. We’d normally assume they’re 10 percent dehydrated unless there are signs that it is worse than that,” Neil explained. To treat fluid loss in a 1kg patient, he advised that half the deficit be replaced during day one (plus their maintenance daily requirement), then a quarter on day two and a quarter on day three. Neil stressed that more birds are saved by good nursing – appropriate fluid and nutritional support as well as patient care – than by any medical or surgical procedure.
Before you begin, it is important to have hospital cages that can maintain a patient between 80°F and 90°F (26.7°C to 32.2°C), controllable radiant heat and accurate weighing scales, Neil said.
“In terms of routes for fluid therapy, we would only recommend intra-osseous in very, very debilitated patients where you cannot find an IV port. We’d use the distal ulna or proximal tibio-tarsus,” he noted. In his practice, syringes of fluid are kept in a baby milk-bottle warmer so they are always available at the right temperature. Remember that subcutaneous fluids can’t be given to all species, he warned: toucans, hornbills and penguins, for example, have subcutaneous air sacs, so putting fluids into them could cause them to drown.
Prior to surgery, every patient needs a full physical examination and their medical histories re-evaluated, said Neil. “We need to consider and correct dehydration, anaemia, hypoglycaemia, hypothermia and any electrolyte- and acid-based disturbances.” The bird should be weighed so all parenteral medication can be drawn up in advance. All surgical cases must have a venous access port and they must all be intubated.
Importantly for avian surgery, you need illumination and magnification. “When you use magnification, you see your hand tremor and that gives you a better ability to control it,” Neil explained. “For instruments, we want standard-sized handles with miniaturised ends. Preferably counterbalanced because that reduces the likelihood of finger fatigue. And we want finger-rolling action. We sit down, rest our forearms and want to pass the needle through the tissue with the needle holders by rolling our finger. It’s much more controlled and we want to minimise tissue damage.”
Because the instruments are delicate, they must be looked after well. In his basic kit, Neil has:
- Ratcheted needle holders with pen-shaped handles (to allow finger-rolling action)
- A large pair of scissors (to prevent abusing the small pair)
- A fine pair of scissors ρ Harris ring-tipped forceps
- A Volkman spoon
- A couple of pairs of very fine artery forceps
- An Alm or similar retractor
- Sterile cotton buds
Anaesthesia and therapeutics
Safe medications and doses will often be species specific, Neil said. He also reminded delegates about restricted drug use in food-producing species and the obligation to record every prescription-only medicine used in these patients. Anaesthesia is used to reduce stress on the bird rather than to immobilise it. “Gas exchange is 10 times more efficient than in mammals, so overdose with a volatile agent is much easier in birds,” the speaker warned. “If the nurse is not experienced with avian surgery, I would suggest weighing the patient [and] giving it a parenteral agent to give you 30 minutes surgical anaesthesia. If you stick to the lower dose, you can repeat that once.” He also urged delegates to be very careful with local anaesthetic, citing the lethal dose of 4mg/kg in birds.
Remember the fundamentals of how surgery in birds is different. Think about equipment, anaesthesia, microsurgical instruments and operating position. “And practise,” Neil urged, “go to wet lab training and do the techniques in front of specialists.” The take-home message was that though it is essential to be thoroughly prepared, veterinary surgeons shouldn’t be afraid of avian surgery.