MODERN CONCEPT OF BLOOD TRANSFUSION IN VETERINARY PRACTICE

Pashu Sandesh, 28 March 2018

Dr Rajesh Kumar Singh

Introduction:

Richard Lower in 1665 transfused the blood in a dog for the first time in the history. With the help of latest techniques and equipment developed after 1950, blood transfusion became more popular in veterinary medicine. Blood transfusion has made considerable advancements in veterinary medicine in recent times.
One of the major obstacles to blood transfusion in veterinary practice is the absence of appropriate donor animals. Identification of possible donors in advance of blood requirements allows life-saving transfusions to be administered quickly and safely. This article describes the indications of transfusion, selection of donors, a safe collection of blood, administration of whole blood product and associated transfusion reactions that occur during transfusion.

Indication for blood transfusion

The most important factor in determining the need for transfusion is the clinical conditions of the patient. Transfusion is always indicated in an anemic patient that is exhibiting signs of clinical compromise such as weakness, anemia, dyspnea, and ataxia. Many authors have recommended that transfusion automatically is performed whenever a patient’s PCV drops below 20 percent (Picher and Turnwald, 1985).

Following simple diagnostic tests should be performed prior to blood transfusion.

1. PCV determines the degree of anemia before transfusion, thereby providing a baseline for continued monitoring.

2. Examination of a blood smear to determine reticulocyte count, the presence of leukemia.

3. Evaluation of serum or plasma for the presence of icterus or hemoglobinemia.

4. Evaluation of hemostatic parameters such as platelet count, prothrombin time and activated partial thromboplastin time, if a bleeding disorder is suspected.

5. Performance of a slide agglutination and/or Coombs test if immune-mediated hemolysis is suspected. Further tests such as routine clinical chemistry, radiography, bone marrow aspiration and biopsy may be performed to determine the underlying cause of anemia.

Selection of ideal donors

Great care must be taken that the donors are healthy and completely free of diseases that may be transmissible in the blood. The donor body temperature should be normal and mucous membrane pink. Preference should be given to donors with high hematocrit and hemoglobin levels. Clinically healthy, fully vaccinated dog weighing not less than 25 Kgs, having a PCV of over 35% and ideally negative for CEA 1.1-1.2 and 7, is the best donor.

In practice, relatively large quantities of blood can be collected from healthy donors without endangering the animal’s life. A safe upper limit for blood withdrawal is 1 liter per 300 Kg body weight. Dogs and cats can donate 10% of their total blood volume with no adverse effects. The total blood volume in cats and dogs is approximately 66 ml/kg, 90 ml/kg body weight respectively (Turwaid and picher, 1985). Blood can be collected from a donor every 1-6 weeks and it is advisable to check the donor's PCV before each collection to ensure normal red cell regeneration had occurred.  

The volume required by the recipient

To calculate the blood volume required by the recipient, the following equation derived by Pichler and Turnwalf (1985) can be used:

Required PCV minus Recipient PCV

Crossmatching

For performing both types of cross-matching, blood collected in both heparin and EDTA anticoagulants must be obtained from the donor and recipient. Although cross-matching can be performed using slides, this method is less reliable since only serum with high tired antierythrocyte and donor may give a crude indication of compatibility, but this methods is unreliable and is not recommended.

Biological screening test

In the recipient animals, a small amount of blood (200 ml) is infused intravenously and observed for 10 minutes. If there is no reaction within that period, the remainder of blood can be transfused without risk.

Blood typing
Species Blood Group
Canine----- DEA 1.1 and 7
Feline------ A, B, mic
Equine ------A, C, Q
Cattle-------The internationally recognized blood groups in cattle are A, B, C, F, J, L, M, R, S, T and Z. out of these 11 groups, group B and J being the most clinically relevant. The B group itself has more than 60 antigens, thereby making closely matched blood transfusions difficult. The J antigen is not a true erythrocyte antigen but a lipid found in plasma Cattle having anti-J antibodies with a small amount of adsorbed J antigen on erythrocytes but negative J blood group can develop transfusion reactions when receiving

BLOOD COLLECTION TECHNIQUES

• Restraint is achieved using a halter,
• Head tied up
• Sedation: xylazine
• Prepare the collection site in the mid-jugular area
• Local anesthesia
• A small incision in the skin
• Some anesthetic subcutaneously around jugular vein

Collection
• Large bore needle (diameter 4 - 5 mm)
• Raise the vein with a tourniquet( chain, rope with small round block or digital pressure)
• Insert the large bore needle through the skin incision and into the jugular vein
• Blood collected by using a funnel inserted into the top of the collection vessel (plastic
water bottles 1.1/2 ltrs) with anticoagulants
• Agitate gently the collected blood to mix it with the anticoagulant
• Look out for contamination
• After collection of 5 to 8 liters (+/- 10 min), release pressure and remove the needle
• Close the skin with a couple sutures
• For small amounts(450 ml), use human disposable vacuum bags(Terumo)

Anticoagulants solution
• Sodium citrate:
- 100 ml of a 3.8 to 5 % per liter blood
- Make it freshly up a physiological serum with the sodium citrate (crystalline powder)
• Heparin sodium:
- Solution 5000 units in 5 ml vials
- 5000 units for 1-liter blood
• Before Collecting: coat the needle and funnel with the anticoagulant solution, otherwise blood clot forming during collection possible
• Collected blood should be used within two hours

The collection, storage, and transfusion of blood must be done aseptically. The anticoagulant of choice is citrate phosphate dextrose adenine (CPDA-1). Commercial blood bags containing the appropriate amount of anticoagulant for a “unit” (500 mL) are available. Heparin should not be used as an anticoagulant because it has a longer half-life in the recipient and causes platelet activation; also, heparinized blood cannot be stored.
Blood collected in CPDA-1 with added RBC preservation or nutrient solutions may be safely stored at 4°C for 4 wk.

Large animals

Various blood collection technique has been described for large animals including direct transfusion from donor to recipient by the use of shikle's syringe, vacuum pump assisted collection into closed containers, collection into commercially available vacuum bottle systems and collection by gravity flow. Sodium citrate is the anticoagulant of choice and should be placed in the collection container in an amount sufficient to give a final concentration of
0.3%. The blood should be swirled during collection to assure proper mixing
with anticoagulant. Plastic bag blood collection sets containing anticoagulants are commercially available and are entirely satisfactory for both collection and transfusion of small quantities of blood. For larger transfusion, sterilized, glass or sodium citrate can be useful, as blood should be filtered through sterile gauze before it is used for transfusion.

Small animals

Ideally, the blood is collected from the jugular vein or carotid artery with the dog either sitting or lateral recumbent. The needle should be held as still as possible during collection of blood and a second person should gently mix the collection bags to ensure that the anticoagulant is thoroughly mixed with the blood. Canine blood is normally collected directly into a human blood collection bag which contains enough acid citrate dextrose (ACD) or citrate phosphate dextrose (CPD) anticoagulant. The use of ACD or CPD anticoagulants allow the blood to be stored for up to 3-4 weeks without significant loss of red cells viability, provided it is kept at between 40°C and 50°C. Ideally in dogs blood should be given into the cephalic or jugular vein via an intravenous catheter. In severely hypotensive or pediatric patients, the blood can be given into the proximal femur using an 18-20 gauge intravenous needle or a spinal needle placed in the trochanteric fossa.

Dosage and administration of blood

The dosage is calculated by the percentage of hemoglobin present to which, is increased (at least 75% of the normal level). Since an animal contains 40 ml of blood per pound body weight the formula used is-

40 x Body weight in Pounds/100 ml of blood required to raise the Hb
level 1%.
Blood that has been stored in the refrigerator before administration should be warmed slowly to room temperature. If the blood is required quickly it may be warmed by passing it through the coiled tubing of the set immersed in a warm (38-40°C) water bath. Cold blood should not be infused; it is more viscous and therefore takes a long time to transfuse, it provokes vasoconstriction, lowers body temperature and may also produce cardiac arrhythmias. Initially, the infusion should be slow and the recipient watched carefully for any sign of transfusion reaction. If after 20-30 minutes there are no problems the rate of infusion may then be increased.

Procedure for transfusion -

Administration of blood

• Restraint the recipient animal
• Sedation mostly not necessary
• Prepare the insertion area
• Local anesthesia
• Small skin incision
• Insert a 12 gauge 8 cm catheter and suture in place
• Attach the giving set to the catheter
• Transfusion of 5 to 8 liters will take 30 to 45 minutes
• Monitor transfusion reactions 

Transfusion reactions

Animal receiving blood or blood products should be monitored closely during the transfusion period. If symptoms associated with a potential transfusion reaction are recorded, the transfusion should be stopped and the cause of the reaction investigated. Although transfusion reaction can occur due to poor storage or administration techniques, most significant reactions are associated with the administration of mismatched transfusions.

Signs of potential transfusion reaction

Urticaria, erythema or pruritus, vomiting, vocalization, pyrexia, dyspnea, tachypnea, coughing, tachycardia or bradycardia, tremors or convulsions, shock, cardiopulmonary arrest, anorexia, and jaundice.

It is indeed fortunate that cattle and swine rarely have demonstrable nature isoagglutinins that cause transfusion reaction of blood. Blood group does exist, however that present the threat of transfusion reaction on subsequent transfusion. Exceedingly complex blood groups systems have been described, most active of which from a transfusion of incompatible blood are immediate anaphylactic reactions characterized by arched back, straining muscular trembling, dyspnea, coughing, salivation, lacrimation, tachycardia, hemoglobinuria, and hyperthermia. Since the transfusion reaction is epinephrine responsive, it can be avoided by avoiding repeated transfusion and discounting the transfusion and administering epinephrine should sign of a reaction appear. The practitioners should not be hesitant about giving a blood transfusion in animal practice.

Compiled by-DR RAJESH KUMAR SINGH, JAMSHEDPUR, 9431309542,rajeshsinghvet@gmail.com