DEALING WITH SICK PARROTS: PART TWO – FLUID THERAPIES

The high metabolic rate of small psittacines means they may feed and drink when presented and will continue to do so under your care. However, it is likely that additional support will be required to top up voluntary intake. It is best to assume all critically ill birds are dehydrated and acidotic. Assessment of the packed cell volume (PCV), electrolyte and protein levels can be helpful, but this usually requires an anaesthetic and it may be contraindicated in the initial phase of supportive care.

Any fluids provided must be at body temperature so hypothermia does not set in. An infant bottle warmer can be used to maintain the fluid’s temperature.

In mild cases, fluids can be given by crop tubing, which promotes normal gastrointestinal function. This is performed in the same way as crop feeding – once you are happy with the placement, a bolus of liquid can be provided directly into the crop or proventriculus. Do not apply pressure to the crop during feeding and subsequent release to avoid causing regurgitation. Mammalian solutions are also suitable for use. Very sick birds may regurgitate fluids, leading to the risk of aspiration pneumonia. Birds with gastrointestinal disease, impaction, foreign bodies, crop trauma or facial trauma will probably require an alternative route. Many cases will need parenteral fluids initially, with or without oral fluids.

Subcutaneous fluids are generally reserved for mildly dehydrated patients, but are easy to provide. They are best provided in the inguinal skin fold between the patient’s leg and abdomen. The axillary region can also be used. Due to birds’ poor skin circulation large volumes cannot be absorbed quickly. Adding hyaluronidase to the fluids markedly increases the surface area available for absorption and leads to quicker uptake. Any pain associated with injection is subsequently reduced. Up to one per cent of bodyweight is tolerated at each site and temporary lameness can result with large volumes. Maintenance therapy generally necessitates fluids be provided six times a day, but this is a simple route and can be performed by an individual in a collapsed bird, or with the help of an assistant to physically restrain livelier birds.

Avian patients should not be given intracoelomic fluids due to the absence of a diaphragm and the presence of an air sac system, which occupies and links all body systems including the lungs, thereby potentially flooding the air sacs with fluid.

IO therapy

Intraosseous (IO) therapy is an effective technique and can be an alternative route for fluid therapy in parrots, using either the tibiotarsus or ulna. This method can only be carried out on the anaesthetised patient (which may already be collapsed) as the procedure is considered painful.

Take care to avoid infection as this could lead to osteomyelitis, and antibiosis is advisable to prevent this. However, for very small patients requiring rapid venous support, IO administration of fluids may be the only option. Spinal needles with a central stylet or hypodermic needles can be used. Boluses of fluids can be slowly administered and repeated at intervals, or a giving set or syringe driver can be attached. Most bird species can be given IO fluids, but care needs to be taken regarding sites of administration. In psittacine patients, the femur and the humerus are pneumatised (contain air) and involved in respiration. These should never be used for fluid administration.

The distal or proximal ulna, or the tibiotarsus in front of the stifle joint, are potential sites, but for longer term administration, the distal ulna is preferred. For placement, the ulna is flexed and the needle advanced through the dorsal condyle of the ulna into the medullary cavity. For tibiotarsal placement, the cnemial crest, or tibial plateau, of the bone is readily palpated just distal to the stifle joint and the needle can be advanced into the medullary cavity.

The needle can be left in situ so repeated bolus volumes can be provided throughout the treatment period, including drugs, saving the veins for serial blood monitoring. IO fluids have a lag time of roughly five minutes compared to two minutes for intravenous (IV) fluids. If an IO needle can be placed quickly, the actual time of fluids entering the circulation may be quicker.

Correct placement can be confirmed by drawing back until blood is obtained (a small amount of saline may have to be injected first), or a larger test injection can be provided. Swelling at the site indicates the fluid has gone into the soft tissues. Radiography can also be used to confirm correct placement.

IO fluid therapy is painful if given at high speed, so attaching an infusion pump is best. The flowline spring infusion system is useful if you do not have access to an infusion pump or, alternatively, slow boluses can be given.

IV fluid therapy is the preferred route for many cases, particularly in severely dehydrated birds. With practice, IV fluid therapy can be given to birds as small as 30g (particularly short term) and this nullifies the IO route in most cases. The site used depends on the species and, in many cases, general anaesthesia will be required for correct placement.

IV routes may be difficult to access and veins are often very small and fragile while many birds will not tolerate being attached to a giving set. Therefore, it is common for a one-off bolus of fluids to be provided directly by needle. Crystalloids, colloids, haemoglobin glutamer-200 or blood can be given via this route. In many cases, the author also provides a multivitamin solution via this route.

Avian veins are fragile and prone to haematoma, so finegauge needles and catheters (24 to 27 gauge) will be required. Fluid boluses can be provided via a catheter: 10ml/kg to 15ml/kg is given initially, followed by a maximum rate of 10ml/kg/hour (during anaesthesia). Fluid is provided based on the requirements of the case and the practicality of repeat boluses being given by staff.

Placement

The jugular veins are used as a first line for all psittacine birds. A variety of catheters can be used and placed in either vein. The right vein is larger and is normally used, but the right vein is also mobile and fragile and can easily lead to haematoma formation. Catheters are placed by parting the feathers with spirit to find the apterium over the neck. The catheter is sutured in place and a light conforming bandage collar can be wrapped around the neck. The catheter has an injection port attached and fluids can be given by a bolus. The catheter, once in place, is very stable, difficult for psittacines to remove, is well tolerated and enables one individual to provide fluid therapy. The author has used this technique in birds as small as 30g, using a 24g catheter.

An alternative

Although the basilic vein is easy to access for blood sampling, it is very fragile and not recommended for permanent catheter placement. However, it can be used for single bolus injections of fluid. The basilic vein is therefore second choice in psittacines as the catheters are easily removed and can bleed out from the placement site.

This route is probably the best during anaesthesia to ensure minimal interference with the surgeon and reduce the risk of dislodging an endotracheal tube or other items towards the bird’s head. Plucking a few feathers may be necessary to gain access. The vessel passes over the proximal ulna in the medial side of the wing where a catheter can be placed (generally smaller than a jugular catheter). The catheter is sutured in place and an additional loop of suture material is passed around the secondary feathers at their base to prevent kinking. Generally, birds of more than 100g can be catheterised by this route. An injection port can be screwed to the catheter and fluids can be provided by bolus injection.

Nebulisation in small psittacines provides warmed, humidified air, offering easy, stress-free fluid therapy. The nebuliser provides a small droplet size (3nm) that can penetrate the smallest of airways. In patients with respiratory compromise, using oxygen at six litres/minute can help stabilise a bird that was too dyspnoeic for a clinical examination – therapeutic agents can also be provided via this route.

Routine maintenance

Fluid therapy is required to provide for maintenance, deficits and ongoing anticipated losses. Maintenance fluids requirement is 50ml/kg/day for birds. In ill birds it is assumed they are fluid deficient. This is taken as 10 per cent for the typical sick bird. The volume of fluid required is calculated by multiplying the estimated percentage deficit by the bodyweight in kilograms. In the first 24 hours, 50 per cent of this deficit should be replaced, with 25 per cent replaced on day two and day three alongside maintenance requirements.

Both glucose saline and lactated Ringer’s solution (LRS) are ideal for birds. Glucose saline provides fluid to temporarily replace the lost circulatory volume, but also provides an immediate energy source. Therefore, it is the fluid of choice for an initial IV or IO bolus. LRS is useful as the lactate is converted to bicarbonate in the liver to correct the acidosis. It is the routine maintenance fluid in birds. A simple regime is to use LRS subcutaneously, prior to anaesthesia, and then an IV or IO line can be placed for further fluid therapy.

Colloids are used to expand plasma volume containing large molecules, which do not easily pass out of the vasculature. They are essential for cases of hypovolaemic shock and where the PCV is below 20 per cent. The ultimate colloid is whole blood, but it carries the risks of transfusion reactions, spread of infectious disease and low availability. Donors should ideally be from the same species, although pigeons have been used to transfuse psittacine birds. The blood should be taken into acid citrate dextrose and approximately one per cent of the bird’s bodyweight can be safely obtained from a healthy donor.

Synthetic colloids are also available that don’t carry oxygen to the tissues, but expand plasma volume. These have a cost advantage and are easily obtained. Finally, haemoglobinbased oxygen carriers can be used, which potentially do carry oxygen, although there have been no clinical studies to assess effectiveness. They are expensive and only come in large pack sizes designed for a 20kg dog.

Should the facilities for blood pressure monitoring be available, then fluid therapy, colloid and crystalloid use can be titrated to match the bird’s exact requirements. Many practitioners mix colloids and crystalloids and use them routinely for critically ill or surgical patients.

• Some of the drugs mentioned in this article may not be licensed for use in the treatment of parrots.