Whole blood is collected from a donor animal for blood transfusion purposes into a blood bag containing citrate phosphate dextrose as the anticoagulant. Donor animals should be selected with care and strict attention should be paid to the blood collection technique to maintain sterility at all times. A single blood transfusion bag can be used if collection of whole blood only is desired, however double, triple and quadruple blood bags (a single whole blood collection bag with various satellite bags) are used for producing and separating components within a sterile closed environment.
Donor selection
One of the main problems with blood transfusion medicine is finding a reliable source of good donor animals. Many veterinarians in private practice use their own animals as donors. Veterinary schools either keep a colony of donor animals or have a list of outpatient donors. The establishment of a variety of blood banks in the USA has greatly facilitated transfusion medicine by making blood and components available to everyone. However, there is a high cost in purchasing these products, therefore whole blood transfusion will sometimes remain as the only viable option for private veterinary practice.
Donor animals should be healthy (have normal results on hemograms, biochemical panels, fecal examinations and urinalysis every 6 to 12 months), fully vaccinated and checked for a variety of infectious diseases (such as as Babesia, Ehrlichia and Toxoplasma). Dogs and cats should be heartworm negative and dogs should be on heartworm preventitive medication. Large-breed animals are often preferred as a large amount ofblood can be withdrawn with minimal sedation. The Greyhound is the most commonly used blood donor, however this breed may not be optimal as their red blood cells have reduced oxygen-carrying capacity, they have low vWf:Ag values and generally lower platelet counts than other breeds of dogs and (due to their high hematocrits) yield a small amount of plasma. All donor animals should be preferably blood typed. The ideal canine blood donor is DEA 1.1, 1.2, and 7 negative, whereas ideal donor horses are Qa and Aa negative.
Collection technique
In dogs, commercially available human blood collection bags can be used for blood donation (these bags collect up to 450 ml of blood). However, the amount of blood that can be withdrawn from cats is too small for these collection systems. Special pediatric collection systems (for collection of 75 ml blood) can be modified to collect 35 to 40 ml from cats and to produce fresh or fresh frozen plasma under sterile conditions. Aseptic technique should be used to collect blood from donor animals. The site should be clipped, surgically scrubbed and sterile gloves worn. Generally, the jugular vein is used for donation in all animals. Venipuncture should be clean with rapid blood flow to minimize platelet activation. After collection, direct pressure should be applied to the site to attain hemostasis. Some institutions use mild vacuum pressure to facilitate blood collection. Dogs over 27 kg can safely donate up to 16 ml/kg blood every 3 weeks. Sedation should be avoided if possible, especially if the blood is used for platelets, as some sedatives and anesthetic agents can interfere with platelet function. However, under some situations, general anesthesia may be required and this appears to have little effect on the quality of the blood product. The blood should be immediately refrigerated and stored refrigerated until use for transfusion or separation into components. Some authors have recommended the use of DDAVP pre-collection to maximize the yield of vWf:Ag in the blood donor bags.
