Equine plasma and its constituents are valuable and potentially life-saving resources used by diagnostic laboratories, researchers, veterinarians, and physicians. Equine plasma may be incorporated into culture media or used as the matrix in pharmacokinetic studies. Highly specific antibodies may be isolated from equine plasma and used in the production of scientific assays. Plasma is harvested from donors and infused into equine patients for the management of protein-losing enteropathies, nephropathies, coagulopathies, failure of passive transfer, and other medical conditions. Hyperimmune equine plasma is commercially manufactured and sold for prophylactic administration and treatment of several clinically important infectious diseases of horses.1–3 Equine plasma is the starting material used in production of hyperimmune equine fragment antigen-binding products (ie, Fab and F[ab]2), which are commonly referred to as antivenoms and antitoxins in the human health-care industry. These pharmacological agents are frequently the only treatment available for envenomations and bacterial intoxications.
Plasmapheresis is the technique currently used to harvest large volumes of equine plasma. Plasmapheresis involves removal of whole blood, addition of an anticoagulant, fractionation of anticoagulated whole blood, harvest of plasma, and return of cellular components back to the donor.2,4 Plasmapheresis was first performed in horses via a manual technique. In each of 2 reports5,6 published in the 1970s, investigators described similar methods for manual plasmapheresis procedures in horses. Investigators aseptically placed large-bore stainless steel needles into jugular veins of donor horses. Tubing sets were attached to the needles, and whole blood was collected in sterile glass jars that contained an anticoagulant. Gravity sedimentation was achieved by placing jars in a refrigerator for 12 to 24 hours, and the plasma fraction the was siphoned into sterile collection jars. The remaining cellular mass was resuspended in a volume of saline (0.9% NaCl) solution similar to the volume of plasma harvested. The cells and saline solution were warmed in a water bath to 37°C and then transfused back into the donors.
Currently, instruments are used by researchers and commercial operations to perform automated plasmapheresis procedures in horses. These instruments connect to the donors via sterile tubing sets, which form a closed-loop collection system.7 Automated instruments withdraw whole blood and infuse it with anticoagulant at a controlled rate. Anticoagulated whole blood is fractionated via centrifugation or filtration techniques.4,7,8 Isolated plasma is diverted to an attached collection bag or bottle. Simultaneously, the concentrated cells are returned to the equine donors.
Research facilities and commercial operations repeatedly perform plasmapheresis procedures on horses at 14- to 30-day intervals and harvest a maximum of approximately 20 mL of plasma/kg of donor body weight during each procedure.2,7,9,10 Although a number of facilities use automated plasmapheresis procedures to harvest a high volume of sterile plasma from horses, only a few studies have been conducted to examine these procedures and their effects over time. In 1 study,9 investigators evaluated the effects of automated plasmapheresis procedures on clinical, hematologic, biochemical, and coagulation variables in horses after a single plasmapheresis procedure. In another study,2 investigators evaluated the replacement rate of serum proteins after plasmapheresis in 8 donor horses. The horses used in that study were part of a commercial plasmapheresis program and had previously undergone 6 to 18 plasmapheresis procedures at a mean of once every 30 days prior to the study. The rate of protein replacement was only evaluated once and was not monitored throughout the duration of the donor horses' involvement in the plasmapheresis program.
The purpose of harvesting equine plasma is to obtain valuable proteins, including IgG. Equine plasma collection facilities strive to harvest high-volume, high-quality plasma as frequently as possible without causing sustained protein depletion in donor horses. The purpose of the study reported here was to determine the effects of intensive serial plasmapheresis on total plasma protein and total IgG concentrations in donors throughout the duration of their involvement in a plasmapheresis program.
Life Design Prime 14, Nutrena, Minneapolis, Minn.
Quest gel, Fort Dodge Animal Health, Fort Dodge, Iowa.
West Nile Innovator + EWT, Fort Dodge Animal Health, Fort Dodge, Iowa.
RabVac 3, Fort Dodge Animal Health, Fort Dodge, Iowa.
Fluvac Innovator EHV-4/1, Fort Dodge Animal Health, Fort Dodge, Iowa.
Pinnacle IN, Fort Dodge Animal Health, Fort Dodge, Iowa.
West Nile Innovator + EW, Fort Dodge Animal Health, Fort Dodge, Iowa.
Nolvasan surgical scrub, Fort Dodge Animal Health, Fort Dodge, Iowa.
ChloraPrep One-Step antiseptic sponge, Medi-Flex Hospital Products, Overland Park, Kan.
Hospira Inc, Lake Forest, Ill.
Becton-Dickinson, Franklin Lakes, NJ.
Supramid, S. Jackson Inc, Alexandria, Va.
4R-2252 Plasmacell-C set, Baxter-Fenwal, Lake Zurich, Ill.
Autopheresis-C A-200, Baxter-Fenwal, Lake Zurich, Ill.
Baxter-Fenwal, Lake Zurich, Ill.
EPS-20L collection bag, Charter Medical, Winston-Salem, NC.
Plasmalink pooling bottle, Baxter-Fenwal, Lake Zurich, Ill.
Dormosedan, Pfizer Animal Health, Exton, Pa.
Torbugesic, Fort Dodge Animal Health, Fort Dodge, Iowa.
Plasma-Lyte A, Baxter-Fenwal, Lake Zurich, Ill.
Immuno-Tek Horse IgG ELISA, ZeptoMetrix Corp, Buffalo, NY.
EL808 Ultra microplate reader, Bio-Tek Instruments Inc, Winooski, Vt.
KC Junior microplate data analysis software, Bio-Tek Instruments Inc, Winooski, Vt.
SAS, version 9.1, SAS Institute Inc, Cary, NC.
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