Small Animal Blood Bank
Blood Banking Information for Veterinarians
DOGS :: CATS :: Donor Selection :: Blood Component Products ::
Crossmatching :: Transfusion Administration :: References for Veterinarians
BLOOD TYPE GROUPS IN DOGS
13 blood type groups have been identified in dogs. Dogs can have more than one blood type. Typing sera is available for dog erythrocyte antigens (DEA) 1.1, 1.2, 3, 4, 5, and 7. Typing cards can be used to screen dogs for type DEA 1.1, but having further testing done by a commercial lab is recommended.
DEA 1.1, 1.2 and 7 are the most antigenic blood types. If DEA 1.1 or 1.2 + blood is given to a negative dog that has been previously sensitized through transfusion, pregnancy or existence of natural isoantibodies (a rarity), a fatal acute hemolytic crisis may occur. DEA 1.1 + blood is more immunogenic than DEA 1.2 +.
A universal canine donor tests + for only DEA 4. Ideally only universal donors would be included in a donor programs, but most commonly donors are DEA 1.1, 1.2 and 7 -. Dogs that are DEA 1.1+ may be used as donors if the recipient is DEA 1.1+.
Dogs rarely have isoantibodies against other blood types, so in MOST cases, it is safe to give a dog a blood transfusion without blood typing the donor and recipient or crossmatching prior to the transfusion. Despite this, it is recommended that all recipients be crossmatched prior to receiving a blood transfusion (particularly dogs which have received a previous blood transfusion, which are a breeding bitch or which previously whelped).
BLOOD TYPE GROUPS IN CATS
There are 3 identified blood types in cats: A, B, and AB. The frequency of blood type varies depending on breed, and geographic area. Type A is more common than Type B and AB is rare.
Most cats are born with isoantibodies against the blood type they are not. Type B cats have strong naturally occurring antibodies against Type A blood. As small an amount as 1 ml of Type A blood given to a Type B cat can cause a fatal transfusion reaction.
Type A cats have weak antibodies against Type B blood. If type B blood is given to Type A cat, the mean half life of RBCs is 2 days (29-39 days in compatible transfusion). The transfusion is clinically ineffective, since the RBCs are functional for a short period of time. Type A kittens born to a Type B queen are at risk of developing neonatal isoerythrolysis. Blood typing can be done with an in-house typing card as a screening test for blood typing.
BLOOD DONOR SELECTION
Qualities for canine donors: healthy, no history of metabolic or heart disease or seizures, lean body weight of > 50#, and ~1-7 years of age. They should be on no medications, except heartworm and parasite preventatives. Potential donors should have a good temperament, be neutered and nulliparous, and have jugular veins that are easily visualized and palpated. They should be current on vaccines.
Once a dog's blood type is determined and is acceptable, screening is done for metabolic and infectious diseases: CBC, biochemical profile, U/A, fecal exam, von Willebrand's factor, and testing for Dirofilaria immiti, Ehrlichia canis, Babesia canis, B. gibsoni, Brucella canis (in intact or previously bred dogs), and Bartonella. Testing for specific infectious diseases depends on what diseases are endemic.
Greyhounds have been promoted as an ideal blood donor because of their amenable disposition and high PCV. Many greyhounds come from racing backgrounds (in Florida) and there is a seroprevalence of Babesia canis of 46% in these dogs. American Staffordshire terriers and pit bull terriers have a high seroprevalence for B. gibsoni. Both breeds should be PCR negative for babesiosis before donating blood.
Qualities for feline blood donors: healthy, no history of metabolic or heart disease or seizures, lean body weight of > 10#, and ~1-7 year of age. Potential donors should be easy to handle, neutered and nulliparous, and have jugular veins that are easily visualized and palpated. They should be current on vaccines.
There is no feline universal blood type, due to naturally occurring isoantibodies against the opposite blood type. Once a cat's blood type is determined and is acceptable, screening is done for metabolic and infectious diseases: CBC, biochemical profile, urinalysis, thyroid hormone (in age-appropriate animals), fecal exam, FeLV, FIV, Mycoplasma hemofelis (previously Haemobartonella), Bartonella spp. Testing for specific infectious diseases depends on what diseases are endemic. Other infectious disease testing to consider includes heartworm disease and ehrlichiosis.
Feline donors should be kept indoors only and be vaccinated annually. They should be maintained on flea/tick preventative monthly, and have a physical exam, CBC, biochemical profile, urinalysis, fecal, heartworm test and infectious disease testing done annually. Monthly heartworm preventative is recommended in endemic areas for the safety of the donor.
BLOOD COMPONENT PRODUCTS
Fresh whole blood: collected immediately prior to transfusion and supplies viable platelets, RBCs, WBCs, all clotting factors and plasma proteins. One canine unit is usually ~500 cc, feline unit ~60cc. A dose of 20 ml/kg will potentially raise the PCV 10%.
Stored whole blood: whole blood can be stored for ~28-35 days in CPDA-1 collection bags. It contains RBCs, WBCs, plasma proteins, but platelets are only viable for 2 hours after refrigeration and the more labile clotting factors (V, VIII) are only viable for 24 hours. A dose of 20 ml/kg will potentially raise the PCV 10%.
pRBCs: is prepared by separating whole blood into red blood cells and plasma. pRBCs may be refrigerated for 28-25 days. One canine unit is ~ 200 cc, feline ~30 cc. A dose of 10 ml/kg will potentially raise the PCV 10%.
Fresh frozen plasma (FFP): is plasma separated from fresh whole blood and frozen at -20oC to -30 oC within 6-8 hours of collection from the donor. It contains all clotting factors, including labile factors V and VIII. The clotting factors are viable for 1 year. After 1 year, FFP is relabeled as frozen plasma, to reflect the loss of clotting factors. Dose for coagulopathies is 6-20 ml/kg, repeated as necessary. This dose is ~1 unit of FFP/10-20 kg of body weight. Multiple units of FFP may be needed because of the short half life of clotting factors. FFP is not diluted before administration. Because of the limitations of FFP, other colloids should be considered for treatment of hypoalbuminemia in patients with normal coagulation. A dose of 45ml/kg will increase serum albumin by ~ 1 g/dl.
Frozen (stored) plasma (FP): is prepared by separation of plasma and RBCs after centrifugation. It can be prepared at any point during whole blood storage. Plasma prepared > 6-8 hours after blood collection only contains small amounts of clotting factors V and VIII. It still contains all Vitamin K-dependent factors and thus is effective in the treatment of warfarin toxicity. It also contains plasma proteins. Canine unit~ 200 ml, feline unit ~25 ml. It can be stored up to total of 5 years (1 year as FFP and 4 years as FP, or 5 years as FP) at -20oC.
Cryoprecipitate: is prepared from FFP, which is thawed at 0-6oC. The resulting precipitate is cryoprecipitate. It has a concentration of clotting factor VIII, von Willebrand's factor, and fibrinogen 10 fold > than FFP. It also contains clotting factors XI and XIII and fibronectin. It can be stored for one year at -20oC. Dose: 1 unit/10 kg, repeated as necessary.
CROSSMATCHING
Prior to administration of a blood product, recipients ideally should be crossmatched (dogs and cats) and typed (cats). Crossmatching is similar to blood typing, except that specific antisera are not used, and consists of a major and minor part. The major is the crossmatching of donor RBCs with recipient serum. The minor is the crossmatching of recipient RBCs with donor serum. Incompatibility is seen as hemolysis or agglutination. An apparently compatible crossmatch should be checked microscopically for agglutination. The major crossmatch should always be compatible, although the minor crossmatch is of less importance. If the major crossmatch is incompatible, yet the transfusion takes place, the recipient will destroy all of the transfused RBCs.
Cross matching is done to decrease the risk of transfusion reactions in previously sensitized patients or those with natural isoantibodies. It also helps to decrease the risk of sensitizing a patient if more than one transfusion is anticipated or in intact breeding bitches and queens. Even when a crossmatch is compatible prior to a transfusion, reactions can still occur. The crossmatch does not include assessment of WBCs or platelets that are the main source of many immediate transfusion reactions. Even if blood type specific components are transfused, crossmatching is recommended because all RBC antigen groups have not been fully characterized. If crossmatching is not available, universal donor blood should be used in dogs. Cats must be blood typed prior to transfusion.
TRANSFUSION ADMINISTRATION
Prior to administration blood product: check bag to be certain the correct product and blood type is being transfused and that the product is a normal color and consistency. All frozen/refrigerated products should be warmed to <37oC before administration to prevent hypothermia. Once blood is warmed to <37oC, it deteriorates rapidly and should be used immediately or discarded. Excessive heating will damage proteins and clotting factors and decrease the oxygen carrying capacity of RBCs. When a rapid transfusion is needed, refrigerated blood can be administered without warming. Place all blood products in a plastic bag when thawing in a water bath to avoid contamination of infusion ports. Patients can be given diphenhydramine (0.5 mg/kg) SQ or IM prophylactically at the time of blood product administration to try to minimize risk of transfusion reaction.
Routes of administration: IV (central or peripheral vein) or intraosseous catheter administration of plasma or blood can be done. IV catheter size affects blood flow rate, but small catheters do not cause hemolysis of blood products during transfusion. In normal dogs, ~95% of RBCs transfused through an intraosseous catheter into peripheral circulation in <5 minutes. An intraosseous catheter, spinal needle, bone marrow needle, IV catheter, or normal hypodermic needle may be used for intraosseous transfusions. A 20 gauge needle works well in neonates or small exotic pets. The trochanteric femoral fossa, medial tibia and iliac crest are common sites for intraosseous catheter placement. Plasma products can be given intraperitoneally if necessary, but RBCs are poorly absorbed.
Equipment used to administer: blood products should be transfused through a commercially available blood administration set containing a 170-270 um filter to remove clots and debris formed during storage. Gravity flow is adequate for administration, but infusion pumps can be used if they due not damage RBCs (check with manufacturer). The IVAC 530 pump can infuse blood up to 200 ml/h without causing hemolysis.
Rate and time: transfusions should be completed within 4 hours to prevent bacterial contamination. No medication should be added to blood products. No fluid should be added to decrease viscosity, except for 0.9% saline. Fluids containing calcium (i.e. LRS) may overcome the anticoagulant affects of citrate, leading to blood coagulation. Hypotonic crystalloids (i.e. 5% dextrose in water), may cause hemolysis.
Transfusion rate depends on the status of the recipient. In patients hypovolemic due to massive bleeding, blood products should be transfused as rapidly as possible. In patients with heart disease, the rate should be < 4 ml/kg/hour.
REFERENCES FOR VETERINARIANS
Fluid Therapy in Small Animal Practice, DiBartola, pp. 451-464.
The Veterinary Clinics of North America, Small Animal Practice, "Hematology", pp.1261-1294, 1401-1418.
Current Veterinary Therapy XIII, "Blood Transfusion Guidelines" pp. 400-403.
Clinical Techniques in Small Animal Practice, May 2004, pp. 55-94.
Wadrop KJ, Reine N, Birkenheuer A, et al. Canine and Feline Blood Donor Screening for Infectious Disease, JVIM 2005;19:135-142.