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Quiz: Xenotransfusion in a Cat

Rebecca Smith, LVMT, VTS (ECC), University of Tennessee

Adesola Odunayo, DVM, MS, DACVECC, University of Tennessee

Internal Medicine

|January/February 2021|Peer Reviewed|Web-Exclusive

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Quiz: Xenotransfusion in a Cat

FIGURE 1 Hazel was presented with hematuria, lethargy, and recent unresponsiveness. Image courtesy of Dr. Rose Cherry and Dr. Kryssa Johnson

Xenotransfusion (ie, the transfer of blood from one species to another) has been included in the medical literature since the early 1600s, with the first procedure described as transfusion of blood from a lamb to a young boy. Although xenotransfusion is no longer commonly used due to the availability of modern-day transfusion techniques (eg, blood component therapy, species-specific products, commercial blood banks), unique circumstances may make it a practical alternative in cats. Clinicians should be aware of the clinical indications, complications, and expected outcomes of this procedure to ensure the benefits outweigh the risks.

Hazel, a 6-year-old spayed ragdoll cat, was presented unresponsive and in lateral recumbency after a 5-day history of hematuria and anorexia (Figure 1). She was current on vaccinations and flea and tick preventives, lived indoors only, and had no previous medical concerns.

On physical examination, her temperature was 94.4°F (34.7°C), heart rate was 150 to 170 bpm, respiratory rate was 44 breaths per minute, mucous membranes were pale, capillary refill time was prolonged at >3 seconds, blood pressure was 50 mm Hg systolic (Doppler), packed cell volume/total solids were 7%/5.4 g/dL, blood glucose was 204 mg/dL (11.32 mmol/L; reference interval, 80-120 mg/dL [4.44-6.66 mmol/L]), and lactate was 97.3 mg/dL (10.8 mmol/L; reference interval, <22.5 mg/dL [<2.5 mmol/L]).

An immediate blood transfusion was needed to improve oxygenation and tissue perfusion. 

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Quiz: Xenotransfusion in a Cat

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True or false: Because Hazel has never received blood products in the past, it is acceptable to perform a transfusion using any available feline blood, as the likelihood of a reaction to the first transfusion is minimal.

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A blood-type test was performed on Hazel using a point-of-care feline blood-typing card (Figure 2). Hazel was determined to have type B blood, which is less common than type A and usually not immediately available for transfusions at the point of care. Type A feline packed RBCs were available at the clinic.

A rapid feline blood-typing kit using ≈3 drops of the recipient's EDTA whole blood and phosphate-buffered saline. The recipient has type A blood, as shown by strong agglutination in the type A box but not in the type B box. If there is agglutination in the control box (ie, auto-agglutination saline screen), the cat is auto-agglutinating, and a blood type cannot be determined without additional steps (eg, washing the cells to remove antibodies). Specific blood-typing instructions should be read carefully, as different manufacturers may interpret tests differently.
A rapid feline blood-typing kit using ≈3 drops of the recipient's EDTA whole blood and phosphate-buffered saline. The recipient has type A blood, as shown by strong agglutination in the type A box but not in the type B box. If there is agglutination in the control box (ie, auto-agglutination saline screen), the cat is auto-agglutinating, and a blood type cannot be determined without additional steps (eg, washing the cells to remove antibodies). Specific blood-typing instructions should be read carefully, as different manufacturers may interpret tests differently.

FIGURE 2 A rapid feline blood-typing kit using ≈3 drops of the recipient's EDTA whole blood and phosphate-buffered saline. The recipient has type A blood, as shown by strong agglutination in the type A box but not in the type B box. If there is agglutination in the control box (ie, auto-agglutination saline screen), the cat is auto-agglutinating, and a blood type cannot be determined without additional steps (eg, washing the cells to remove antibodies). Specific blood-typing instructions should be read carefully, as different manufacturers may interpret tests differently.

A rapid feline blood-typing kit using ≈3 drops of the recipient's EDTA whole blood and phosphate-buffered saline. The recipient has type A blood, as shown by strong agglutination in the type A box but not in the type B box. If there is agglutination in the control box (ie, auto-agglutination saline screen), the cat is auto-agglutinating, and a blood type cannot be determined without additional steps (eg, washing the cells to remove antibodies). Specific blood-typing instructions should be read carefully, as different manufacturers may interpret tests differently.
A rapid feline blood-typing kit using ≈3 drops of the recipient's EDTA whole blood and phosphate-buffered saline. The recipient has type A blood, as shown by strong agglutination in the type A box but not in the type B box. If there is agglutination in the control box (ie, auto-agglutination saline screen), the cat is auto-agglutinating, and a blood type cannot be determined without additional steps (eg, washing the cells to remove antibodies). Specific blood-typing instructions should be read carefully, as different manufacturers may interpret tests differently.

FIGURE 2 A rapid feline blood-typing kit using ≈3 drops of the recipient's EDTA whole blood and phosphate-buffered saline. The recipient has type A blood, as shown by strong agglutination in the type A box but not in the type B box. If there is agglutination in the control box (ie, auto-agglutination saline screen), the cat is auto-agglutinating, and a blood type cannot be determined without additional steps (eg, washing the cells to remove antibodies). Specific blood-typing instructions should be read carefully, as different manufacturers may interpret tests differently.

FIGURE 2 A rapid feline blood-typing kit using ≈3 drops of the recipient's EDTA whole blood and phosphate-buffered saline. The recipient has type A blood, as shown by strong agglutination in the type A box but not in the type B box. If there is agglutination in the control box (ie, auto-agglutination saline screen), the cat is auto-agglutinating, and a blood type cannot be determined without additional steps (eg, washing the cells to remove antibodies). Specific blood-typing instructions should be read carefully, as different manufacturers may interpret tests differently.

Given Hazel’s rapid decompensation and concern for impending death, what course of action is preferred?

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Xenotransfusion can be considered when there is an absence of available feline type-specific blood products. Other acceptable indications for xenotransfusion include which of the following?

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Many canine blood products are available (Figure 3). Although transfusion reactions to canine blood products in cats receiving xenotransfusion for the first time are rare, in vitro studies using major and minor crossmatching have suggested inherent incompatibilities exist.2

Canine packed RBCs, canine lyophilized cryoprecipitate, and canine fresh frozen plasma
Canine packed RBCs, canine lyophilized cryoprecipitate, and canine fresh frozen plasma

FIGURE 3 Canine packed RBCs, canine lyophilized cryoprecipitate, and canine fresh frozen plasma

FIGURE 3 Canine packed RBCs, canine lyophilized cryoprecipitate, and canine fresh frozen plasma

Which blood product should be used to minimize Hazel’s chances of an immediate reaction to canine blood?

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Hazel was given 40 mL of DEA 1.1-negative canine packed RBCs over 1 hour. Administration was very rapid because she was hemodynamically unstable (Figure 4). Vital signs were monitored continuously, and thermal support was provided as needed. Post-transfusion, her temperature was 98.9°F (37.2°C), heart rate was 210 bpm, respiratory rate was 28 breaths per minute, mucous membranes were pale pink, capillary refill time was <2 seconds, blood pressure was 110 mm Hg (Doppler), PCV/TS were 24%/5.9 g/dL, blood glucose was 114 mg/dL (6.3 mmol/L), and lactate was 27.02 mg/dL (3 mmol/L). Hazel appeared to be significantly better and was admitted to the hospital for further supportive care, diagnostics, and monitoring.

Allogenic blood transfusion in a cat. Feline allogenic transfusions can be administered via syringe pump through a microaggregate filter without causing significant damage to the erythrocyte surface. Canine erythrocytes are subject to lysis if administered through a microaggregate filter due to the small pore size, thus decreasing the longevity of the cell in the recipient circulation. It is therefore recommended to administer canine erythrocytes through a filter size no less than 170 µm, preferably via gravity delivery.11 Most transfusions are given over 4 hours, but Hazel's transfusion was rapid because she was unstable.
Allogenic blood transfusion in a cat. Feline allogenic transfusions can be administered via syringe pump through a microaggregate filter without causing significant damage to the erythrocyte surface. Canine erythrocytes are subject to lysis if administered through a microaggregate filter due to the small pore size, thus decreasing the longevity of the cell in the recipient circulation. It is therefore recommended to administer canine erythrocytes through a filter size no less than 170 µm, preferably via gravity delivery.11 Most transfusions are given over 4 hours, but Hazel's transfusion was rapid because she was unstable.

FIGURE 4 Allogenic blood transfusion in a cat. Feline allogenic transfusions can be administered via syringe pump through a microaggregate filter without causing significant damage to the erythrocyte surface. Canine erythrocytes are subject to lysis if administered through a microaggregate filter due to the small pore size, thus decreasing the longevity of the cell in the recipient circulation. It is therefore recommended to administer canine erythrocytes through a filter size no less than 170 µm, preferably via gravity delivery.11 Most transfusions are given over 4 hours, but Hazel's transfusion was rapid because she was unstable.

FIGURE 4 Allogenic blood transfusion in a cat. Feline allogenic transfusions can be administered via syringe pump through a microaggregate filter without causing significant damage to the erythrocyte surface. Canine erythrocytes are subject to lysis if administered through a microaggregate filter due to the small pore size, thus decreasing the longevity of the cell in the recipient circulation. It is therefore recommended to administer canine erythrocytes through a filter size no less than 170 µm, preferably via gravity delivery.11 Most transfusions are given over 4 hours, but Hazel's transfusion was rapid because she was unstable.

What is the expected life span of transfused canine erythrocytes given to a cat?

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Because canine erythrocytes have a short lifespan in feline recipients, Hazel may need a second transfusion if anemia remains a concern, especially because the cause of anemia is currently undetermined. Type B feline blood was ordered, but it may take several days to arrive. A second xenotransfusion could be considered if it is performed before antibodies against the canine erythrocytes are formed.

How long postxenotransfusion can antibodies against canine erythrocytes be detected?

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Following xenotransfusion, Hazel was hospitalized for 4 days. Diagnostics indicated primary immune-mediated thrombocytopenia with secondary anemia, and treatment with doxycycline and prednisolone was initiated while infectious disease and rickettsial titers were pending; results were negative. Vital signs and PCV/TS were monitored daily. Four days postxenotransfusion, PCV/TS was 25%/6.2 g/dL with hemolyzed serum. Anemia appeared static, so Hazel was discharged (Figure 5), with a follow-up examination and blood work scheduled 3 days after discharge.

Hazel after being discharged. Images courtesy of Dr. Rose Cherry and Dr. Kryssa Johnson
Hazel after being discharged. Images courtesy of Dr. Rose Cherry and Dr. Kryssa Johnson

FIGURE 5 Hazel after being discharged. Images courtesy of Dr. Rose Cherry and Dr. Kryssa Johnson

FIGURE 5 Hazel after being discharged. Images courtesy of Dr. Rose Cherry and Dr. Kryssa Johnson

On discharge, what information should be emphasized to the owner of a patient that has received a xenotransfusion? 

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Hazel was returned for a recheck examination 3 days after discharge. Her PCV/TS had dropped to 19%/7.6 g/dL; however, the anemia was strongly regenerative (reticulocytes, 245.2 x 10³/uL; reference interval, 15-90 x 10³/uL). The owner reported that Hazel appeared well and had a normal appetite. No further transfusions were considered, and a recheck was scheduled for 2 weeks postxenotransfusion, unless behavior changes occurred prior. 

At the 2- and 4-week rechecks, Hazel appeared well. Her PCV was trending up. At 6 months postxenotransfusion, Hazel was no longer anemic and was healthy.  

True or false: Hazel’s case does not represent the typical expected outcome because she did not require an additional transfusion after xenotransfusion.

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Quiz: Xenotransfusion in a Cat

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