Temperature control. 

Hypothermia is the main cause of anaesthetic deaths and complications. Body temperature of most birds is 40-42oC. Birds under anaesthesia lose temperature very quick, and this is even more pronounced in small birds (due to increased surface/weight ratio); when the feathers are plucked from large areas of the body (feathers are used by the bird to regulate its temperature); when the skin becomes wet (eg, with the excessive use of disinfectants such as alcohol); or when procedures such as coeliotomies are done. Fluid should be warmed up to bird body temperature before administration. Temperature control using a rectal (cloacal) thermometer is mandatory. Temperature setup in small animal surgical theatres is too cold for birds, and a room temperature around 22-250C is recommended. Other ways to avoid hypothermia are the use of heat mats, heat lamps, hot air, heated sandbags or gloves filled with hot water. 

Cardio-respiratory control. 

Intubation and assisted ventilation is the best way to avoid respiratory complications, such as apnoea, hypoventilation, atelectasis or blockage of the endotracheal tube with secretions. Birds are easy to intubate, and lubricated un-cuffed tubes are used as tracheal rings are closed (complete). Very small birds can also be intubated, but the chances of obstructing the endotracheal tube with secretions increase. Open anaesthetic circuits are used, because birds do not have the strength to move air through a close circuit. Birds in sternal recumbence breathe better, but this can be corrected in other positions using assisted ventilation. A pre-anaesthetic respiratory rate should be taken with the animal free of stress, and that rate should be applied during anaesthesia; alternatively, 10-20 breaths/min can be used in those birds not breathing by themselves, and 2 breaths/min in those breathing spontaneously (to compensate for possible hypoventilation). The use of a capnograph (should be kept at 30-45 mmHg) is useful to monitor efficacy of ventilation. Ventilation (using an ambu-bag or a mechanical ventilator) should not exceed 10-20 cm H2O to avoid trauma to lungs and air sacs.

Cardiac output should be monitored with the use of a Doppler, generally over the cubital (radial) artery (associated with the basilic or cubital vein). The presence and intensity of pulse can also be appreciated placing a finger over the cubital artery. Pulsoximeters are not calibrated for avian haemoglobin and therefore do not provide reliable results. Heart arrests are usually fatal in birds, and therefore the cardiovascular function should be supported during anaesthesia using an intravenous or intraosseous catheter and fluid therapy. Blood pressure can be obtained using a Doppler and placing a small cuff in the proximal humerus or tibiotarsus. 

Be gentle 

Most birds undergoing anaesthesia will be less than 600 grams, and procedures should be done carefully and gently to avoid unwanted consequences. Tracheal tubes should be lubricated and inserted gently to avoid trauma to the tracheal rings, which can develop into a tracheal stenosis. Excessive fluid therapy can produce lung oedema. Overinflation of the lungs (generally with an ambu-bag) can produce trauma to both lungs and air sacs. During surgery, resting a hand over the keel of the bird can impede normal breathing. 

Withholding food in not necessary for passerines and parrots, although it is always recommended to have an empty crop before surgery. Carnivore and piscivore birds easily vomit under anaesthesia and food should be withheld for 4-12h, depending on the size of the bird. For raptors, it is worth checking that a cast has been produced after the last meal. Anyway, quick intubation reduces the chances of tracheal aspiration. Induction with gaseous agents is done with a face mask, and the bird is ready for intubation in 1-2 minutes (when using 1 L/min O2 and gas at the maximum concentration that the vaporiser allows). Isoflurane is the anaesthetic agent of choice. Sevoflurane can also be used, but it is more expensive and the efficacy is very similar to isoflurane. Injectable agents are rarely used, although there are also effective and safe protocols: alfaxalone, propofol or a combination of ketamine with an alpha-2 agonist can be used in birds, both intravenously and intramuscularly (*propofol can only be given IV). 

For intubation, the tongue should be pulled forwards with atraumatic forceps. The glottis will be seen at the base of the tongue, as birds do not have epiglottis. The lubricated tube is placed and secured, and anaesthesia is maintained with oxgen (500 mL/kg/min) and gas (2-3% isoflurane, 3-4% sevoflurane). An air sac tube placement can help relieving respiratory distress associated to partial or total blockage of the trachea, and gas anaesthesia can also be delivered through the air sac tube when a tracheoscopy or a surgical procedure in the trachea needs to be performed. Organomegaly, ascites or severe lung/air sac pathology may complicate the placement of an air sac tube, and previous radiographs may help detect these complications. 

Monitoring a bird during anaesthesia 

 is of paramount importance in order to reduce associated risks. The use of Doppler, capnograph and blood pressure has been discussed previously. CNS reflexes are also helpful to assess depth of anaesthesia. During a surgical anaesthesia, palpebral reflex should be absent but corneal reflex should be present. The loss of corneal reflex indicates an excessively deep plane of anaesthesia. If Doppler, capnograph and blood pressure cuffs are not available, the anaesthesia should be monitored with reflexes (to assess plane of anaesthesia); 2-20 assisted ventilation per minute, depending on spontaneous breathing (to make sure oxygenation is correct); auscultation of heart rate over the keel or over the back; and assessment of pulse intensity placing a finger gently over the brachial artery. 

Recovery 

 is usually rapid once the inhaled anaesthetic agent has been turned off. Ventilation with 100% O2 should be continued until full recovery. The endotracheal tube should be removed only when the bird is conscious and moving the head. Oxygen can still be provided after extubation using a face mask. The patient will be covered with a towel to avoid hypothermia and to prevent injuries due to wing flapping or excessive bending of the neck. This stage of recovery is very important and mortality can occur if the bird is not managed properly. The bird should only be released back into its cage or pen once is able to perch or stand. Keeping the bird in a quiet place with low-intensity lighting helps avoiding problems during this stage. 

The study of pain in birds has advanced significantly over the last decade. Studies have been done in some species, clarifying which analgesic drugs are more effective in avian patients, although it has also been seen important differences among species regarding doses and frequency of use. 

A pre-surgical evaluation should be done in any patient undergoing anaesthesia. This may involve good history taking, visual and physical exam, bloodwork, radiographs, etc. For acute conditions (such as fractures) diagnostic tests and surgery may be postponed until the patient is stable. In some situations, even with critical patients, anaesthesia (with intubation and proper control of the cardio-respiratory function) may be preferable to physical restrain with associated stress (such as for blood sampling, radiographs, etc.). 

Anaesthesia and preparation of the patient have been covered before, and plastic transparent drapes can be used in order to better conserve animal’s body temperature. Povidone-iodine or chlorhexidine can be used as skin sterilising agents. Due to the small size of most patients, it is very important to keep blood loss to a minimum. Radiosurgery units can be used in order to reduce blood loss and surgical time. Tissues should be handled gently, and tools such as rat-toothed forceps or towels clamps can damage the thin and inelastic skin of birds. Microsurgical instrumentation (such as ophthalmic instruments, haemoclips), good lighting, and magnifying glasses facilitate the surgical procedure, avoid traumatic tissue handling, and allow the veterinary surgeon a more comfortable body position (which prevents neck and back pains). Eyelid retractors or Lone Star® retractors are excellent for intra-abdominal procedures. 

Suture materials commonly used in birds should be absorbable, synthetic, monofilament and degraded by hydrolysis. In a study, polydioxanone (PDS®) produced the least amount of tissue reaction and took more than 120 days for degradation, while polyglactin 910 (Vicryl®, a multifilament material) produced more reaction but was degraded in less than 60 days. Cyanoacrylate tissue glue can also be used, but may delay healing if it runs between the apposed tissues, creating a physical barrier for healing. 

Toe amputation 

Due to avascular necrosis (circumferential constriction by fibres or scabs) or trauma (aggression, open fractures). Less common causes are frostbite, lymphoma, mineralisation of vessels, Knemidocoptes infection). Place a tourniquet higher up in the leg and allow extra skin on incision to close up. For very small birds just cut the toe and cauterise with silver nitrate sticks or apply some tissue glue to stop bleeding. 

- Feather cyst. 

Common genetic condition in canaries. Also seen in psittacines. The feather cannot erupt and the cyst keeps growing. Multiple cysts may be affecting the same bird. Surgery is done for large cysts, but other cysts will continue growing in other feathers. Most commonly found affecting the wings. A tourniquet is placed, the cyst is opened and emptied, and the follicle is removed with scalpel or cauterised with radiosurgery. Bleeding should be controlled. Skin closure may not be possible and the area my need to heal by second intention, with or without the use of bandages. 

- Cranial skin defect 

Trauma can produce the loss of skin on the dorsal area of the head. A pedicle advancing flap is recommended for these wounds. Two parallel incisions are done on the skin of the dorsal aspect of the neck, between the defect and the shoulder area, and the flap created is advanced to cover the skull defect. The skin edges are opposed with an interrupted suture pattern 

- Crop surgery. 

Performed to take a biopsy (for evaluation of Proventricular Dilatation Disease, although not commonly used nowadays) or to resolve a crop burn (in hand-reared psittacines that are given formula that is too hot). For biopsy, an area on the lower right side of the crop is prepared for surgery. Some feathers may need to be removed. The skin is incised, taking care not to reach the crop, which is right under the skin and attached to it. The crop is dissected away from the skin and then two stay sutures are placed to exteriorise a section of the crop. Using scissors, a piece of crop (ideally 1× 1 cm) is removed, and the defect is closed with an apposition pattern, which can be reinforced with an inverting pattern on top of it. For crop burns, it is advisable to wait a few days (3- 5) after the injury to better see the difference between dead and viable tissue; following the same technique as for biopsy, the area of dead crop wall is removed. 

- Coeliotomy. 

 Performed in cases of dystocia, prolapse, neoplasia, peritonitis, gastrointestinal foreign body, abdominal hernias or reproductive disease. It should be avoided when the same procedure can be performed using endoscopy. Coeliotomy carries a bad prognosis in very small patients such as canaries and budgerigars. Depending on the organ affected, a lateral or a ventral approach can be performed. 

Orthopaedics 

Fractures of the long bones (humerus, ulna, radius, femur, tibiotarsus and tarsometatarsus) are resolved using external fixation or a combination of an intramedullary pin + external fixation. Fractures of tibiotarsus and tarsometatarsus in very small patients can be managed with a tape splint (ie. compressing the leg between layers of tape). Fractures of the metatarsus in small and medium birds can be managed with a Shroeder-Thomas splint. The humerus and femur are pneumatic bones. In fractures involving the radius and ulna, if one of those bones is intact, then an IM pin can be used to stabilise the fractured bone, using the intact bone as an external stabilisation. The level of functionality expected by the owner may dictate the management of the fracture: a falconer may expect their bird to be suitable for good flying after a fracture, but that may not be the case for a pet parrot. Similarly, wild raptors may require perfect flying after rehabilitation, while some ducks or swans living most of their time in a lake may not. 

Bandages 

Bandages can be used to treat fractures, stabilise fractures before orthopaedic surgery, or treat other conditions such as luxations or wounds. Performing physiotherapy in between bandage changes can help limit complications. Some fractures, like those affecting the coracoid bone, are better managed with bandages. Two bandaging techniques are used for immobilisation of the wing: figure of eight bandage (it does not stabilise the humerus) and full wing bandage (it stabilises the humerus). A ball bandage is commonly used to treat foot problems, such as fractures, luxations, pododermatitis