Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
Goals of Fluid Therapy
1. Administer the least amount of fluids needed by the patient.
2. Restore perfusion and hydration without volume overload.
3. Have a treatment goal.
4. Assess clinical response toward treatment goal.
5. Early intervention.
If it is determined the patient can withstand the stress of handling and treatment then fluid therapy may be initiated. Normosol or Lactated Ringer’s Solution can be administered through the following routes: subcutaneous, intravenous, intraosseous, orally and through the cloaca. Anatomic sites commonly used for IO catheter placement include the distal ulna (larger birds), proximal ulna, proximal tibiotarsal bone and lateral femur (young and small birds). Placement of the IO catheter begins with proper site preparation, similar to epithelial preparation for an IV catheter. A 22-gauge, 1½” spinal needle is the catheter of choice in most psittacine cases although any size needle may be used, provided that a stylet is inserted into the needle prior to placement of the IO catheter into the medullary cavity of the bone.1 When the IO catheter is placed in the distal ulna, the distal wingtip is flexed and then the needle is inserted at 45 to 60° angle, and this angle is reduced once the catheter enters the cortex.2 The needle should be advanced to the hub, stylet removed and the catheter flushed with hepatized saline to the hub, stylet removed and the catheter flushed with heperized saline. The catheter is capped with a PRN and managed as an IV catheter. lntraosseous catheters require more maintenance than an IV catheter and should be flushed 6 to 8 times a day to maintain patency. Subcutaneous fluid therapy is not an effective method of rapid restoration of circulatory fluid volume.3 Adding hyaluronidase (Wydase, Wyeth-Ayerst Pharmaceuticals, Philadelphia, PA) to lactated Ringer’s solution (LRS) for SC fluid administration has been recommended as a method to increase the absorption rate of the fluid into the circulatory system.1
When determining the dehydration deficit of a psittacine patient, the veterinarian must estimate the percentage of deficit prior to calculating replacement fluid volumes. Parameters applied to measure dehydration status in psittacine species include skinfold elasticity, corneal moisture, appearance of the globe and packed cell volume. Dehydrated psittacine chicks have wrinkled and reddened skin, with a sunken face and prominent eyes.4 It is generally believed that in most cases of severe trauma or disease a 5% to 10% dehydrated status should be estimated for the avian patient. The estimated deficit should be replaced over a 48–72 hour period.1 The recommended daily fluid maintenance formula for psittacine species is 100 ml/kg/day, and baby birds consume 2 to 3 times the maintenance fluid levels as adult patients.1 but may range between 50–150 ml/kg/day depending on species of bird being treated. Recent recommendations to compensate for tissue fluid loss are a crystalloid (e.g., LRS) 10 m l/kg + colloid (e.g., hetastarch) at 5 ml/kg increments. The crystalloid/colloid combination given at 1 to 2 bolus infusions will generally raise the blood pressure to greater than 90 mm Hg systolic. Fluids should be warmed before administration and bolus fluids can be given with relative safety 10 or IV over a 3–5 minute period. Once the fluid deficit is replaced and the bird is eating and drinking normally for 2 or 3 days, the maintenance hydration therapy can be discontinued.
Fluids therapy may be replaced through subcutaneous, intravenous or intraosseous administration. Subcutaneous fluid replacement can be achieved using a 26- or 25-gauge needle attached to a syringe filled with a warmed crystalloid or colloidal agent. The sites usually preferred for subcutaneous administration are the featherless inguinal and/or axillary regions of most avian species. Intravenous catheters are placed in the jugular vein of larger birds and median metatarsal of smaller companion avian species. The distal ulna and proximal tibiotarsal bone are the recommended sites for IO catheter placement. Although IO catheter placement is easier in smaller birds, these catheters require more maintenance to prevent plugging. lntraosseous catheters have a similar delivery to IV catheters and are much easier to place, especially in smaller species.
Lactated Ringer’s solution (LRS), 2.5% dextrose in 4.5% saline, and 0.9% saline comp rise the commonly used isotonic crystalloid solutions administered to avian species. The necessity for continuous fluid administration is based on the fact that only 25% of the fluids administered to a bird remain in the vascular compartment 30 minutes after it enters the blood stream.5 Since the patient that presents in shock is often suffering from metabolic acidosis and lactate is metabolized to bicarbonate in the liver, LRS is the fluid of choice.6 Lactated Ringer’s solution can be supplemented with potassium chloride (0.1–0.3 mEq/ kg to a maximum dose of 11 mEq/day) if the plasma potassium and sodium levels are low in the patient due to vomiting or diarrhea (Hernandez, Aguilar 1994). If a patient is hyperkalemic due to severe tissue injury, a catabolic state, or renal dysfunction, LRS is not contraindicated and calcium gluconate (0.5 ml/kg facilitates the movement of potassium across the cell membranes.5 In cases of hydropericardium, pulmonary edema, or increased intracranial pressure without hemorrhage is present hypertonic saline may be useful.5
Plasma, dextrans, and hetastarch are large molecules that do not cross the vascular endothelium and are called colloids.5 These products replace lost protein and help to maintain plasma oncotic pressure and reestablish circulatory volume.6 Caution is advised when considering the use of synthetic colloids in patients diagnosed with congestive heart failure or anuric/ oliguric renal failure because they are excreted by the kidney.6 The recommended dose for hetastarch is 10–15 ml/kg IV for 1 to 4 treatments over a 24-hour period.7 Remember to reduce the volume of crystalloid administration by the volume of hetastarch used to prevent fluid overload.6
Fluid Therapy Information1,8
1. Assess critical patient and stabilize
a. Place in a warm incubator
b. Oxygen supplementation prn
c. Most patients administer warmed crystalloid fluids 3 ml/100 gram body weight
d. Once stabilized diagnostics and treatment for dehydration and hypovolemia
e. Blood pressure?
g. If hypovolemic bolous administration
i. Crystalloids 10 ml/kg and colloids 5 ml/kg until clinical response
ii. Usually 1 or 2 bolus treatments required for effect
2. Estimation formula for fluid deficit based on dehydration status and body weight
a. Estimated dehydration (%) x body weight (g) = fluid deficit (ml)
b. Daily maintenance fluid requirements (4 ml/kg/h) are added to the fluid deficit volume
c. Fluid deficit can be replaced over a 48 to 72 hour period
3. Fluid therapy should be adjusted based on an assessment of patient needs and the disease condition being treated.
4. The daily fluid maintenance in parrots is estimated from 50 ml/kg/day9 to 100 ml/kg/day (Orosz, unpublished data).
5. Maintenance fluid therapy should be provided until the avian patient is fully hydrated and drinking water to maintain its normal hydration status.
6. Intravenous and intraosseous fluid administration should be used whenever possible.
7. Subcutaneous fluid administration is often preferred for avian patients because of their reluctance to maintain and IV or IO indwelling catheter.
8. For patients in shock peripheral vasoconstriction will reduce their ability to absorb subcutaneous fluids.10
9. Subcutaneous fluid administration should not exceed 10 ml/kg/site.10
10. Use isotonic fluid products for subcutaneous fluid administration.
11. Fluids with an osmolarity of 300–320 mOsm/L can be recommended in parrots.
1. Tully TN. Psittacine therapeutics. Vet Clin Exot Anim. 2000;3:59–90.
2. Lamberski N, Danial G. The efficacy of intraosseous catheters in birds. In: Proceedings of the Association of Avian Veterinarians. Chicago, IL; 1991:17–19.
3. Griffin C, Snelling L. Use of hyaluronidase in avian subcutaneous fluids. In: Proceedings of the Association of Avian Veterinarians. St. Paul, MN; 1998:239–240.
4. Clubb L, Wolf S, Phillips A. Psittacine pediatric medicine. In: Schubot R, Clubb K, Clubb S, eds. Psittacine Aviculture Perspectives, Techniques and Research. Loxahatchee, FL: ABRC; 1992:16.1–16.27.
5. Hernandez M, Aguilar R. Steroids and fluid therapy for treatment of shock in the critical avian patient. Sem Avian and Exot Pet Med. 1994;3:190.
6. Joseph V. Emergency care of raptors. Vet Clin Exot Anim. 1998;1:77–98.
7. Stone E, Redig P. Preliminary evaluation of hetastarch for the management of hypoproteinemia and hypovolemia. In: Proceedings of the Association of Avian Veterinarians. Reno, NV; 1994:197.
8. Lichtenberger M. Principles of shock and fluid therapy in special species. Sem Avian Exot Pet Med. 2004;13:142–153.
9. Steinhort L. Avian fluid therapy. J Avian Med Surg. 1999;13:83–89.
10. Dibartola S, Bateman S. Introduction to fluid therapy. In: Dibartola S, ed. Fluid Bectrolyte and Acid-Base Disorders in Small Animal Practice.