Abstract
Plasma transfusion is a mainstay of therapy for many conditions in veterinary medicine including failure of passive transfer of maternal immunoglobulins (FPT), hypoproteinemia, certain coagulopathies, and as immunotherapy for specific infectious diseases (e.g., foals with Rhodococcus equi infection, parvovirus infection in dogs).2,3,6 Improved techniques for blood collection using local donors and establishment of commercial animal blood banks have allowed increased use of this therapy in veterinary medicine.2,3 Unfortunately, the widespread use of plasma in exotic species has been hindered by the logistics of obtaining sources of plasma. This is complicated by the risks associated with anesthesia of the donor animal, ability to separate plasma fractions, and lack of readily available disease screening and cross-matching techniques for these species. This paper describes examples of administration of commercially available equine plasma Polymune, Veterinary Dynamics, Inc., Templeton, California in exotic ungulates for different therapeutic situations.
Case 1: Treatment of Failure of Passive Transfer of Immunoglobulins (FPT)
Signalment: Axis deer (Axis axis), 1 day old, male; wt=3.65 kg
Problem: Failure to nurse.
Diagnostic/therapeutic plan: Neonatal examination performed at 24 hr of age revealed no abnormalities except moderate dehydration and pale oral mucous membranes. No nursing had been observed and the dam moved away when the fawn approached. Bloodwork confirmed failure of passive transfer (negative glutaraldehyde coagulation test1), mild anemia (PCV=27%), and suspected hypoproteinemia based on dehydration (total protein=5.4 g/dl). The decision was made to remove the fawn for a plasma transfusion and hand-rearing. The animal was anesthetized and a jugular catheter placed. Dexamethasone sodium phosphate (0.5 mg/kg) was administered i.v. approximately 10 min before plasma was started. Equine plasma was transfused at 29.6 ml/kg/hr over 50 min (total volume=90 ml). One episode of apnea was treated halfway through the procedure and responded to Dopram (1.4 mg/kg i.v.). Other prophylactic therapy included broad-spectrum antibiotics and fluids (11 ml 5% dextrose in LRS i.v. and 110 ml LRS s.c.). Post-transfusion bloodwork showed a PCV=24% and total protein of 6.0 g/dl.
Follow-up: Dehydration improved and no additional fluids were required. Antibiotics were continued for a total of 5 days. No further complications occurred.
Case 2: Treatment of Hypoproteinemia Secondary to Parasitism
Signalment: Mhorr gazelle (Gazella dama mhorr), 3 yr old, female; wt=36.9 kg
Problem: Chronic weight loss, associated with lactation and parasitism.
Diagnostic/therapeutic plan: Initial evaluation and deworming was performed using a drop chute. Abnormal results included severe anemia with evidence of regeneration (PCV=12.5%, 38/100 nucleated rbc, 12.3% reticulocytes) and hypoproteinemia (total protein=4.1 g/dl, albumin=1.5 g/dl). The animal was anesthetized for additional diagnostic testing and treatment. Two jugular catheters were placed to allow separate transfusions. The animal was pretreated with dexamethasone sodium phosphate (1.1 mg/kg i.v.) and diphenhydramine (0.54 mg/kg i.v.) 10 min prior to starting the transfusion. In order to treat the anemia and hypoproteinemia, both hyperimmune equine plasma (13.6 ml/kg i.v.) and Oxyglobin (polymerized bovine hemoglobin, 6.8 ml/kg i.v.; Oxyglobin, Biopure Corp., Cambridge, Massachusetts) were administered simultaneously through separate lines over 53 min (rate of total fluid administration was 23 ml/kg/hr). Immediate pre-transfusion and post-transfusion bloodwork results were as follows:
Pre-transfusion: PCV=28%, hemoglobin=9.6 g/dl, total protein=5.8 g/dl, albumin=1.6 g/dl
Post-transfusion: PCV=28%, hemoglobin=10.7 g/dl, total protein=6.6 g/dl, albumin=3.2 g/dl
Follow-up: Repeat bloodwork and deworming were performed 13 days later. Results indicated continuous improvement (PCV=37.8%, hemoglobin=13.0 g/dl, total protein=6.5 g/dl, albumin=2.1 g/dl). The animal’s appetite improved within 2–3 days post-transfusion, along with improvement in haircoat and body condition over time.
Case 3: Treatment of Hypoproteinemia Secondary to Infectious Enteritis
Signalment: Chinese muntjac (Muntiacus reevesi), 7 yr old, female; wt=13 kg
Problem: Intermittent diarrhea over a 2-wk course; anorexia and lethargy of 2–3 day duration.
Diagnostic/therapeutic plan: Animal was anesthetized for initial evaluation and treatment. Labwork revealed leukopenia (2600 wbc/cmm), hypoproteinemia (2.4 g/dl), hypoalbuminemia (0.9 g/dl), and hypocalcemia (5.7 mg/dl). Campylobacter spp. was identified in fecal culture. Treatment plan included plasma transfusion, parenteral antibiotics (ceftiofur, enrofloxacin) and other supportive care (parenteral calcium and vitamin E). A jugular catheter was placed and the animal was pretreated with dexamethasone sodium succinate (0.9 mg/kg i.m.). Hyperimmune equine plasma (24 ml/kg) was administered over 45 min (32 ml/kg/hr) while the animal was anesthetized. Some piloerection and increased respiratory sounds occurred approximately 6 min after beginning the transfusion; however, slowing the rate of plasma administration resolved these signs. Pre- and post-transfusion bloodwork revealed a significant improvement in plasma protein concentration with concurrent evidence of hemodilution (pre-transfusion: PCV=38%, total protein=2.2 g/dl; post-transfusion: PCV=18%, total protein=4.4 g/dl). Clinical signs associated with the iatrogenic anemia were not observed.
Follow-up: The animal was more alert and began eating the next day. Antibiotics were continued and diarrhea and anorexia were resolved by 5 days post-transfusion.
Discussion
Other species in which commercial equine or bovine plasma has been used include giraffe (Giraffa camelopardalis), Thomson gazelle (Gazella thomsonii), impala (Aepyceros melampus), sable antelope (Hippotragus niger), bongo antelope (Tragelaphus eurycerus), nyala (Tragelaphus angasii), blackbuck (Antilope cervicapra), banteng (Bos javanicus), gerenuk (Litocranius walleri), and pronghorn antelope (Antilocapra americana).
The authors have used commercially available equine or bovine plasma for transfusion in over 25 cases (in present and former institutions) without significant complications. In most cases, patients were pretreated with either diphenhydramine and/or a short-acting glucocorticoid (such as dexamethasone sodium phosphate) to prevent potential hypersensitivity reactions to the foreign proteins. Rapid rates of transfusion are more often associated with adverse reactions such as tachypnea, piloerection, or increased respiratory sounds. Slowing the rate of infusion usually corrects the problem. Administration of furosemide may also be indicated if signs of pulmonary edema occur. Additional treatments are dictated by the underlying problem and may include antibiotics, nonsteroidal antiinflammatory drugs, tetanus antitoxin, Oxyglobin, dextrose, calcium, crystalloid fluids, and other forms of supportive care.
The advantages of using commercially available plasma are: frozen bags can be kept on hand for immediate use; there are readily available sources and adequate volumes to treat a large animal; donors are prescreened for infectious disease; and ease of use (plasma is delivered frozen in sterile bags). Although there is little data available to determine the efficacy and duration of xenogenic plasma proteins in exotic species, indirect evidence suggests that there are immediate effects such as increase in osmotic pressure (measured by increase in total protein) and possible passive transfer of nonspecific immune factors (such as complement) and specific immunoglobulins (assessed by changes in glutaraldehyde coagulation, salt precipitation, and protein electrophoresis results).3,4 In addition, absence of problems associated with FPT in transfused neonates may also be considered anecdotal evidence.5 However, the effect of plasma transfusion in cases of septicemia and hypoproteinemia is difficult to assess since it is often combined with other therapy.
In conclusion, the availability of commercially available plasma has provided zoo veterinarians with an additional therapeutic option for treating cases of hypoproteinemia, failure of passive transfer of immunoglobulins, septicemia, and potentially certain coagulopathies. Blood samples should be obtained pre- and post-transfusion to document changes in PCV, total protein, tests for passive transfer, coagulation panels, and other relevant hematologic and biochemical parameters. Pretreatment with an antihistamine and/or short-acting glucocorticoid may circumvent an anaphylactic response. Adverse effects appear to be minor and are readily treatable. Although multiple transfusions have not been performed, it is suspected that development of antibodies to foreign proteins may increase the risk of future hypersensitivity reactions. Caution should be exercised when administering antisera or other blood products in the future for these patients.
Acknowledgments
The authors gratefully acknowledge the veterinary and animal care staff of Disney’s Animal Kingdom for their assistance with these cases. In addition, we wish to thank the veterinary and animal care staffs at The Los Angeles Zoo and Busch Gardens for experience in using these products in multiple species.
Literature Cited
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