Abstract

The Galapagos sea lion (Zalophus wollebaeki) is one of two endemic pinnipeds to the Galapagos archipelago. Over the past 30 years, this species had suffered a concerning decline in population and consequently listed as endangered on the IUCN red list.¹ In part, this decline is due to increased risk of exposure to disease related to introduced animals (e.g., cats and dogs) and anthropogenic injuries associated with human population and tourism growth in the in the archipelago.^2,3 Anthropogenic impacts (e.g., boat strikes) and infectious disease have the potential to cause life threatening anemia in Galapagos sea lions, indicating a need to evaluate the possibilities of blood transfusions in this species.^4,5

A total of 26 juvenile sea lions were utilized under research permit PC-31-21. The animals were selected from the El Malecón rookery on San Cristobal Island; each animal was evaluated for health status via a physical examination. Only a few minor health abnormalities were noted including ocular trematodes (38%), lacerations and scars (11.5%), and thin body condition (3.8%). Approximately 3 mL of blood was obtained from each animal and evaluated for abnormalities with a lactometer, pack cell volume/total solids, and i-STAT chem8 cartridge. Hyperlactatemia and hypoglycemia were seen throughout the population; this was likely a spurious error due to time between sampling and evaluating the samples.

The blood from 20 of the sea lions was processed for crossmatching. Each sample was centrifuged for 10 minutes and the plasma was removed for later use. A small sample of red blood cells was removed and washed routinely. Each crossmatched performed mixed two drops of recipient plasma with one drop of diluted donor red blood cells and then incubated at 37ºC for 30 minutes. The crossmatch was then evaluated macroscopically and microscopically for agglutination and hemolysis. Each sample was crossmatched to itself and at least two unique sea lions throughout the project. A total of 100 crossmatches were performed.

Of the crossmatches performed, 77% (77/100) were negative for any reaction, 12% (12/100) had only microscopic agglutination, 4% (4/100) had hemolysis, 4% (4/100) had hemolysis and microscopic agglutination, and 3% (3/100) had a weak positive macroscopic agglutination reaction. Possible explanations for the reactions seen in this study included previous blood exposure due to intra-rookery fighting, hemolysis seen in the plasma samples prior to use, or natural blood types in this species of sea lion.^6–8 Our study indicates that in an emergency situation, a transfusion between Galapagos sea lions would have a high chance of success.

Acknowledgements

All authors thank the Galapagos National Park Directorate (GNPD) for their support and assistance performing this project. Specifically, the authors acknowledge the following GNPD members for their direct role in this project: Maryuri Yepez, Gabriel Vasquez and Jefferson Herrera. The authors also acknowledge the Galapagos Science Center for use of their facilities to carry out the lab work in this study, and especially to Carlos Mena, Sofia Tacle, Ana Carrión and Jessenia Sotamba for all the facilities and assistance in the administrative component. The authors thank Kent Passingham for his help in obtaining supplies for this study. The authors would like to thank the following veterinarians from North Carolina State University for their assistance in this project: Drs. Shelly Vaden, Ashley deMey, Jamie Madigan, Ashlan Westbrook, Carl Thomas, Elsa Sanabria, Jane Kim, Kaitlin Stahl, Kristen Bagley, Khushboo Dass, Marisa Hofmeister, Nicole Freitas, Pheobe Delgado, Sophie Mercer, and Susie Jones. Finally, the authors thank the North Carolina State University College of Veterinary Medicine Clinical Pathology Laboratory for their guidance in developing a crossmatching protocol for this project.

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