Transfusion Medicine for the Companion Animal
Kimberly Baldwin, LVT
The purpose of this lecture is to give an overview of whole blood and component therapy uses. How to calculate for the right amount and what the technician should anticipate and complete when administering these natural colloids.
Before a technician or clinician can accurately decide which blood product may be needed a complete physical exam, history and clinical assessment must be completed.
A complete history is the starting point for determining the patients needs. The technician plays a key role in gathering the appropriate information needed to make a treatment plan for an animal with a suspected bleeding disorder. Questions that allow the owner to recall pertinent information will lead to a better understanding and a quicker assessment of the patients needs. Specific questions to consider may be:
1. Environment in which the animal lives. Examples, indoors/outdoors, free roaming, leash walked, live in the city/on a farm
2. Exposure to any hazardous or household medications
3. Complete medical history
4. Is the animal on any medications, including, non prescriptions
5. Has he received any form of component therapy before
Staff members can create a checklist of questions to be handed to the client when the patient arrives. This can be modified to the many disease processes we see within veterinary medicine.
Patient Evaluation/Physical Exam
Understanding the differences between vascular abnormalities and clotting disorders will help in the diagnosis and treatment of the patient. Epistaxis, hematuria, petechiation usually suggest vascular or platelet dysfunction. Hemorrhage or hematomas usually represent clotting disorders or trauma. There are patients with chronic disease that will present with both underlying problems. Diagnosing and treating the underlying disease will minimize the need for component therapy. Assessing the patients temperature, pulse, respiration, mm color, capillary refill time, auscultating heart and lungs will assist in the treatment plan of the patient. Some helpful laboratory tests that are easily assessable within veterinary practice are:
Packed Cell Volume, Total Protein - to help evaluate the severity of anemia
Chemistry panel/CBC- Evaluate underlying disease. It is important to draw samples before administering component therapy to evaluate organ function, coagulation status, and blood type.
Blood Smear- This will allow to evaluate RBC, WBC morphology and amount. This will also assist with the diagnosis of thrombocytopenia. View slide for even distribution of platelets. Platelets may clump on the periphery of a slide. It is difficult to get an accurate platelet count on cats due to platelet clumping. 8 - 12 platelets per oil immersion are considered normal. One platelet per oil immersion is considered 20,000.
Buccal mucosal bleeding time (BMBT)- evaluates primary homeostasis. A normal BMBT is 3 - 5 minutes. The BMBT is prolonged in cases of thrombocytopenia and vMD.
Activated Clotting Time(ACT) is utilized to determine a clotting factor deficiency. Prolonged ACT's can be seen in heparin or warfarin toxicity, thrombocytopenia or early disseminating intravascular coagulopathy.
Types of Natural Colloids
Plasma is the ideal colloid to increase oncotic pressure and assist with acute hypoprotienemia and "leaky" vessel disorders.
Fresh Frozen Plasma contains plasma proteins, albumin and coagulation factors. It is mainly used for its coagulation factors in cases with liver disease, Disseminating Intravascular Coagulopathy or rodenticide poisoning. It must be separated from whole blood within eight hours to keep all coagulation factors and stored in a freezer at -18C or less. Fresh Frozen Plasma can be stored for up to one year in the -30C or less freezer.
Cryoprecipitate is a plasma concentrate prepared from fresh frozen plasma. It contains fibrinogen, fibronectin, and the factor VIII complex that includes the von Willebrand factor. Cryoprecipitate is harvested from the fresh frozen plasma. Each unit of cryoprecipitate forms approximately 25 - 50ml. It is used in-patients with von Willebrand disease and fibrinogen deficiency
Platelet Products are created by centrifuging whole blood. The supernate plasma contains approximately 75% of the platelets in that volume of whole blood and is administered as platelet rich plasma. Platelet rich plasma should be harvested from whole blood within six hours of collection. The whole blood should be kept at room temperature if the whole blood cannot be spun down immediately. Platelet rich plasma should be administered as soon as possible after separation. Platelet rich plasma is used more frequently in smaller breeds. It requires optimal harvesting conditions to keep platelets viable and large volumes are needed for our larger breeds, therefore, fresh whole blood is used more frequently in those patients requiring both platelet and red blood cell support.
Packed Red Blood Cells contain red blood cells only. This is given to animals who have significant red blood cell anemia (usually PCV of 20% or less) and decreased oxygen carrying capacity.
Fresh Whole Blood contains RBC's, platelets, plasma proteins, and coagulation factors. Indicated for patients with massive hemorrhage or severe liver disease.
Component Therapy Administration and Handling
Whole blood or blood components should not be given solely based on hematocrit or hemoglobin levels. There are cases of chronic disease that the treatment of underlying disease is more crucial than supplying component therapy. Routine clinical assessment (T.P.R., heart rate, pulse quality, mentation) and interpretation of lab values should be the deciding factors in component therapy. A list of Veterinary Blood Banks is available at the end of this article.
In an emergency situation component therapy can be given as an I.V. bolus. Ideally, components should be administered over 4 - 6 hours. Limiting administration to this time frame will reduce the risk of bacterial growth. A blood filter set is designed to remove fibrin clots, debris, and platelet aggregates formed during blood collection and storage and should be used when giving plasma, FFP, packed cells and whole blood transfusions to all species. A syringe filter is also available.
Initially, components should be administered slowly (2ml/lb/hr) to observe for transfusion reactions. The technician should complete a TPR, and evaluate mm color, pulse quality, auscultate heart and lungs before administering a transfusion. The animal should be re-evaluated within 1/2hr after transfusion has begun. If clinical signs remain within normal parameters the component rate should be divided over hours of administration.
Monitor patient for transfusion reaction throughout transfusion. Watch for tachypnea, tachycardia, fever, lethargy, facial swelling, vomiting, diarrhea, and change in mentation.
There should be no medications added to blood or components. The only fluids that can be added or administered simultaneously are .9% Sodium Chloride. Ideally, cells and whole blood should be brought to room temperature in the neonate or hypothermic animal. Large animal breeds will not be compromised by administration of components straight from the refrigerator. Packed Cells and Whole Blood can be stored for up to 30days within the refrigerator. Packed Cells and Whole Blood should be stored in an upright position and inverted routinely while being stored. All products should be labeled with date, donor type, name and expiration date. Plasma, Fresh Frozen Plasma, and Cryoprecipitate should be initially put in a cold water bath in its frozen state. It should be gradually brought to room temperature in a warm water bath. Examine all products on arrival to the hospital for cracks and leaks. Plasma should be used within four hours after unthawing. All frozen products should be stored in a safety storage box to avoid being damaged while in storage.
The amount of whole blood or components will vary with the severity of the anemia or the disease process. Some transfusion options are as follows.
Blood Transfusion Therapy Quick Sheet
Option # 2
2ml/kg increases PCV by 1%
Example 1. 20 kg Dogs PCV was 12% and you wanted
to increase the PCV to 20%
10ml/kg for packed cells
Cryoprecipitate 10ml/kg to effect
Animal Blood Bank
Buddies for Life
Eastern Veterinary Blood Bank
Midwest Animal Blood Services
Penn Animal Blood Bank
Case # 1
Signalment: Two-month-old mix breed puppy
Case # 2
Signalment: Seven year old male, castrated, German
Case # 3
Signalment: Nine-year-old female, spayed, cocker spaniel.
Case # 4
Signalment: 18-year-old Siamese cat