SURGERY AND ANAESTHESIA IN PIGEONS

Recent Advances

By Dr BSc, BVSc, MRCVS, MACVSc (Avian health)

I graduated as a vet in 1979, that’s 33years ago.  At this time, to safely anaesthetise a bird, and see it recover, was regarded as remarkable.  To do major surgery and have the bird survive was considered a small miracle.  Since that time, there have been quantum leaps in medication, techniques and knowledge available to veterinarians.  Anaesthesia and operating on a bird, now carry similar risks to that associated with operating on dogs and cats.  If a bird does die, it is now so unusual, that it should be a cause for investigation. 

It has been said, however, that being anaesthetised, is as close to being dead as you can get, and survive.   Birds now routinely survive procedures because of the safe anaesthetics available to vets and also due to advances in the techniques associated with surgery generally.  Some avian vets regard pigeons as “God’s gift to avian vets” because they are so tough.  Pigeons can recover from major injuries, or severe disease, with appropriate care, where some more fragile species may not.  They are still, however, living things, which need to be managed correctly.  Most fanciers are totally unaware of what is involved in anaesthesia and surgery.  A surprisingly large number of fanciers still regard it as normal to attempt surgeries such as suturing a cut, or removing a skin tumour, on one of their own conscious pigeons.  Others will state how valuable or important a bird is to them, but at the same time, refuse to take the bird to a vet, because they feel they are too expensive.  Truly ironic!  Others are openly critical of vets, after they have taken their pigeon to a general practitioner vet and asked them to do a specialised procedure.  If fanciers need specialist avian veterinary work done, they need to see a qualified avian vet.  I breed sheep, but get a sheep vet to attend to them when they are unwell. 

And so what steps are available to a veterinarian when operating on a bird?  Individual veterinarians use their discretion, depending on the severity of the problem, to decide what is required.

  1. Pre-anaesthetic assessment and treatment – birds are thoroughly examined, and any condition that is likely to compromise recovery is corrected.  If birds have been unwell for a period of time, they are often dehydrated, hypoglycaemic (low blood sugar) and hypothermic (low body temperature).  Sick or injured birds often do not eat or drink enough to maintain an adequate level of energy or hydration.  If necessary, birds are admitted into the clinic, and these problems addressed.  Liquid convalescent diets are available, that can be given via a crop tube (the bird equivalent of a stomach tube) into the crop.  These are nutrient rich, easy to digest, and often given warm.  Balanced electrolyte solutions, eg, lactated ringers, can be given either subcutaneously (under the skin), or through a catheter placed into a vein or bone cavity.  Common veins used are the right jugular (on the right hand side of the neck), the basilic (under the wing) or the medial tarsal (on the inside of the leg).  In many of the long bones in birds, eg, in the wings or legs, entry points are available where catheters can be inserted.  The marrow in birds is quite different than in mammals and appears a bit like “raspberry jam”.  Fluids that are given into this marrow space, are quickly absorbed into the birds circulation.  50mL/kg/day is regarded as normal for maintenance.  Most sick birds are 10% dehydrated.  Additional fluids are usually given over 48hours to correct this.  Unwell birds are usually held in thermostatically controlled heated cages.  Specific medications for identified problems can also be given.  The result is a warm, hydrated bird in a positive energy balance, that is a much better surgical candidate.  Offering this supportive care, dramatically improves the birds chances of handling anaesthesia and a surgical procedure.  If necessary, blood can be drawn for testing.  As a bare minimum, a PCV (concentration of red blood cells) and TP (total protein) will provide an insight into the level of debility. If necessary, more thorough tests, covering biochemistry (organ function tests) and hematology (red and white blood cell parameters), can be done.  In city practices, these results are often available within four hours. 
  2. Pre-anaesthetic medication – 5-10mins before induction of anaesthesia, medications that control pain can be given.  This means less anaesthetic needs to be given through the procedure, the level of anaesthesia is more stable, and the animal is more likely to recover smoothly, and resume eating and drinking sooner.
  3. Anaesthetic induction – a face mask is placed over the birds beak and pure oxygen allowed to flow.  This oxygenates the birds blood.  After about 30seconds, anaesthetic gas is introduced, and the bird then loses consciousness, usually within 1 minute.
  4. Anaesthetic maintenance:
    1. Once the bird is anaesthetised, a tube called an endotracheal tube can be inserted into the windpipe.  This can either be directly connected to the anaesthetic machine or to an intermittent positive pressure ventilator (IPPV machine).  IPPV machines monitor the birds breathing and will breathe for the bird if necessary.  Birds do not have a diaphragm (like a mammal) and have to breathe with their chest wall.  Old or debilitated birds can quickly tire when anaesthetised and may not be able to breathe sufficiently to survive.
    2. Anaesthetic depth can be monitored in a number of ways.  Pulse oximeters measure pulse and heart rate, dopplers measure pulse and blood pressure.  The bird can be connected to an echocardiogram (ECG) to monitor heart function and identify any arrhythmias.  A capnograph, which measures carbon dioxide levels in expired air, can be connected to the airway.  Being able to monitor the depth of anaesthesia accurately, means the bird can be kept as light as possible, ie, given the least amount of anaesthetic necessary, without regaining consciousness.
    3. It is a standard practice in involved surgical procedures to insert a 24G catheter into a vein and connect this to an intravenous drip, or more often, an infusion pump.  These are usually set to deliver 10mL/kg/hr so that the bird can maintain a normal peripheral blood pressure during surgery.  If necessary, a blood transfusion can be given.  This may sound involved, but is remarkably routine.  There is no need to type avian blood, as a reaction can only potentially occur if a second transfusion of the same wrong blood is given.  It is unusual for a pigeon to require a second blood transfusion, and even if this is given, the many different blood types in birds makes the chance of a reaction occurring very small.  Blood can be drawn from a pigeon donor into a heparinised (anti-clotting) syringe and the blood run through a catheter with an on-line micro sieve directly into the 24G catheter in the surgical bird.
    4. Anaesthetised birds are actively warmed either by placing on a heat pad or by a radiant heat lamp.  A bird’s core temperature always drops through surgery for a variety of reasons; they are still, they may lose blood, internal organs that radiate heat are exposed, feathers are plucked exposing skin, etc.  Chilling compromises recovery.
  5. Surgery commences – Feathers are removed (but as few as possible) from the incision site.  The skin is washed in a non-alcoholic (ie, not evaporative and therefore cooling) disinfectant, usually chlorhexidine and the site is draped.  Avian drapes are usually sterile clear sheets of polymer that adhere closely to the skin.  Incisions are made through this into the bird, enabling sterile access to the internal structures.
  6. Surgery technique – blood loss is minimised through good surgical technique.  Bleeding can be controlled through micro-cautery.  Large blood vessels are clamped with tiny metal vascular clips released from an applicator.  Many avian surgeons operate either using an operating microscope or wearing magnifying loupes.  Small instruments are used.  Experienced surgeon/nurse teams that work well together reduce surgery time and increase efficiency.  At surgery’s end, fine absorbable non-irritant sutures, not much thicker than a human hair, are used to close the skin.
  7. Surgery end – the anaesthetic gas is turned off and the bird is allowed to breathe pure oxygen for about one minute.  The endotracheal tube is removed as the bird regains consciousness.  An intramuscular injection of an anti-inflammatory pain killing drug is given.  The bird is placed in a heated cage to aid recovery under supervision.  Food is offered as soon as possible.
  8. Convalescence – post surgical birds are usually held in hospital for 1-4 days to monitor recovery.  Antibiotics, specific medication and pain killers are provided as indicated.  Birds that are slow to eat are crop fed a liquid convalescent diet.  Once the bird has recovered sufficiently to look after itself in the home loft, it is discharged.

Fanciers are encouraged to consult their closest avian veterinarian if an individual bird of value becomes unwell.  Contacting their local veterinary authority, school or board is a good way of finding their closest qualified avian vet.  It is hoped that this brief article gives fanciers an idea of how their bird may be managed if requiring a surgical procedure.