Transfusion medicine for the general practitioner (Proceedings)

* These proceedings were previously published for NAVC 2008.

Selecting Canine And Feline Blood Donors Based On Type:

Dog Erythrocyte Antigens (DEA) are glycolipids and glycoproteins on the surface of the red blood cell. The presence or absence of these DEA defines the blood type of an individual. Currently, it is believed that greater than 13 DEA exist. Of these, 8 are considered international standards (DEA 1.1, 1.2, 3, 4, 5, 6, 7, 8) and antisera (for typing) exist to six of them (DEA 1.1, 1.2, 3, 4, 5, 7). It is also possible to type for DEA 1.3. The blood type of the "universal" canine blood donor varies dramatically based on individual theory, laboratory investigation, clinical experience, or a combination of these. There are two "poles" of the universal donor typing debate.

At one end of the spectrum, is the philosophy that the universal donor is one that is positive for DEA 4 (as are 98% of the population) and negative for all other DEA for which antisera (for typing) exist and negative for all anti-DEA antibody (Ab).1 This approach to selecting the "universal" canine donor is most likely to minimize the likelihood of an acute hemolytic transfusion reaction, maximize the lifespan of the transfused blood and make future cross match most likely to be compatible with the recipient.

At the other end of the spectrum is the theory that because DEA 1.1 is the DEA clinically implicated most often as a cause of acute transfusion reaction in previously sensitized dogs2 , this is the only DEA that we must routinely type for. This approach to selecting the "universal" canine blood donor will maximize the size of the donor pool.

Practical Recommendations for Selecting Canine Donors based on Type:

• Type potential canine donor dogs with card test as DEA 1.1(+) or 1.1(-)

• Only consider using DEA 1.1(-) donors OR use DEA 1.1(+) donors for DEA 1.1(+) recipients and DEA 1.1(-) donors for DEA 1.1(-) or 1.1(+) recipients

• Proceed to further screening (see below)

Selection of feline blood donors based on blood type is much more straightforward than the canine system. Cats have three possible blood types: A, B, and AB. In the Northeastern United States, Type A cats account for approximately 99.7% of the feline population while Type B accounts for approximately 0.3% of the population. Type AB is extremely rare.3 Twenty to 45% of Exotic and British Shorthair Cats, Cornish and Devon Rex and 11-20% of Abyssinian, Barman, Persian, Somali, Sphinx, and Scottish Fold are type B.4 Unlike dogs, cats possess strong naturally occurring antibody to the opposite blood type. Consequently, inappropriate transfusion of Type A blood into a Type B cat will result in death. Transfusion of Type B blood into a Type A cat will result in an acute hemolytic transfusion reaction, but will probably not be fatal. To further illustrate the importance of feline blood typing, we can examine the phenomena of neonatal isoerythrolysis. Type A kittens born to a Type B queen will receive strong anti-A antibody in the colostrum resulting in life threatening hemolysis. Feline blood typing is available through commercial laboratories or via an available card test.a,b More recently, a new feline erythrocyte antigen designated Mik has been identified to which naturally occurring antibody also appears to exist in Mik (-) cats. Mik (-) cats may develop acute hemolytic transfusion reactions after being transfused with Mik (+) but AB compatible blood. It appears that a majority of cats are Mik (+).5

Practical Recommendations for Selecting Feline Donors based on Type:

• Type potential feline donors as Type A or B. Try to identify a donor of each type to be available for donation.

• Only consider using Type A blood for Type A cats and only consider using Type B blood for Type B cats

• When transfusion is urgent, transfuse with type specific blood.

• When transfusion is elective, crossmatch to identify

• Proceed to further screening (see below)

Selecting Canine And Feline Blood Donors (Factors Other Than Type):

Numerous selection factors other than blood type are critical to ensuring the safety of canine and feline blood transfusions. Screening for these factors can be somewhat time-consuming and costly, however, if it prevents morbidity or mortality to the donor or the recipient, then the increased effort is well worth the added time and expense.

After we have identified dogs with suitable blood type for donation (see above), in the Northeastern United States, we must screen for infectious diseases6 including Ehrlichia canis (IFA), Babesia canis and B. gibsonii (PCR), Mycoplasma haemocanis (Haemobartonella sp.) (PCR), Ehrlichia genus (PCR), Leishmania (IFA), and Heartworm disease (Dirofilaria immitis) (Ag). Appropriate donors should have negative antibody titers to Ehrlichia canis, and Leishmania spp., negative Babesia spp. PCR, negative Mycoplasma haemocanis PCR, and negative Ehrlichia genus PCR as well as a negative heartworm antigen test (concurrently receiving preventative).c Recent concern regarding the blood-borne transmission of Leishmaniasis to a number of patients at a veterinary teaching hospital has prompted the recommendation to avoid using Foxhounds for donation and to consider random testing of the general donor population.7 Additional infectious disease testing that may be recommended includes Brucella canis (RSAT), Bartonella vinsonii (IFA), and Trypanosoma spp (IFA). In addition to being free from infectious disease, potential donors should be less than 8 years of age, have a normal CBC, Serum Biochemical Profile, and Urinalysis, no previous medical problems, a body weight greater than 40pounds, no concurrent medications, an appropriate vaccination history, no previous transfusion history, and a personality that will allow for sustained restraint for blood collection. The author currently also evaluates donors for von Willebrand Factor levels. All screening with the exception of blood type and von Willebrand factor level should be repeated on an annual basis.

Additional screening (beyond blood type) for feline blood donors in the Northeastern United States is similar to that utilized in dogs. Infectious disease screening should evaluate potential donors for FeLV (Ag), FIV (Ab), Mycoplasma haemofelis and haemominutum (PCR), and Bartonella spp. (PCR). Due to the behavior of FeLV and the immune response to it, the author currently screens cats initially for FeLV using an antigen test, followed by a second test after 3 months of complete isolation from other cats. Suitable donors should be FeLV negative, FIV negative, and have negative PCR for Mycoplasma spp. Donor cats should weigh greater than 10lbs, have normal CBC, Serum Biochemical Profile, and Urinalysis, no previous medical problems, no current medications, a good vaccination record, no previous transfusions, and a personality conducive to phlebotomy. Many cats require sedation for blood donation purposes. Regarding environment, donor cats must not have any contact with other unscreened cats, must NEVER go outside, must NEVER have contact with screened cats that go outside, and must be re-screened on a yearly basis. Generally, it is most convenient for donor cats to live in the clinic / hospital where their environment can be well controlled (avoiding other cats). Finally, due to the significant incidence of occult cardiomyopathy in the feline population, the author recommends echocardiographic assessment of donor cats annually as a "donor-safety" factor.

Collection Of Blood For Transfusion:

Prior to blood collection, all canine and feline donors should be weighed, examined, and have a small blood sample drawn for PCV or Hgb determination. If sedation is necessary, the author routinely uses an opioid in dogs (hydromorphoned or butorphanole ) and ketamine / midazolam IV or isofluranef by mask in cats.

The area over the jugular vein should be clipped and a surgical preparation performed. For dogs, we routinely use a commercially available closed collection system containing CPDA-1 anticoagulant.g CPDA-1 consists of citrate for anticoagulation and phosphate, dextrose, and adenine as precursors for ATP production. Collection in cats is generally performed using an open system consisting of syringe(s) with a 1ml CPDA-1 per 9ml of blood and a 19g butterfly catheter. Risks of bacterial contamination using an open system are significantly greater than those with a closed system. 400-450ml of whole blood may be collected from dogs and 40-50ml of whole blood may be collected from cats. On rare occasion, cats and dogs may show signs of hypovolemia after donation requiring rapid intravascular volume expansion with IV fluids. If this happens, donation protocol may need to be adjusted. Whole blood should be used immediately if an open collection system was used. To retain clotting factor function, whole blood should be used or processed into components within 8 hours of donation.8 Whole blood and packed red blood cells collected into CPDA-1 from a closed collection system can be stored in a strictly temperature controlled refrigerator at 4°C for up to 35days with the addition of additive solutionsh to improve RBC viability. The blood bags should be turned daily.

Blood Product Administration:

Most transfusions in veterinary medicine are performed electively, however, in emergency situations like hemorrhagic shock, blood and blood products can be administered as rapidly as is necessary (using a pressure delivery system). Blood and blood products should ALWAYS be delivered via a commercially available 170(m blood filter.i A filter with low dead space is best used in cats and small dogs receiving less than 60ml of blood or blood product.j Filtration of the blood will eliminate blood clots and other large particles that could cause embolic disease in the recipient. Elective transfusion of whole blood or packed red blood cells should begin slowly (1-3ml over 5min in cats and 0.25ml/Kg over the first 30min in dogs) while monitoring for signs of transfusion reaction (see below).9-10 If no reaction is noted, the transfusion may be delivered over 1-4 hours while intermittently evaluating for any evidence of a transfusion reaction. Recipients with underlying heart disease or other conditions that may predispose to hypervolemia should receive their transfusion slowly to avoid volume overload. Whole blood or blood products should NEVER be infused over a period of time longer than 4 hours due to the risk of bacterial proliferation within the product.

Transfusion Reactions:

Acute immunologic transfusion reaction may occur when antibodies to donor RBCs are present in the recipient plasma. An example would be the administration of Type A blood to a type B cat (you will remember that all type B cats have potent anti-A antibody). In this clinical situation, the donated cells would be rapidly destroyed in 1-2 hours and the recipient would likely die. A similar situation in which a DEA 1.1 negative dog is transfused twice (more than 3-5 days apart) with DEA 1.1 (+) blood. Antibody to DEA 1.1 in the plasma of the recipient would cause the rapid hemolysis of the transfused RBCs.2 Other less severe signs of acute immunologic transfusion reactions include fever and urticaria. Life-threatening acute immunologic transfusion reactions can be avoided in most cases by the administration of type specific blood and performing major and minor cross match when indicated. Examples of acute non-immunologic transfusion reactions may include air embolism, blood clot embolism, hypocalcemia because of citrate (anticoagulant used in blood collection) toxicity, and bacterial contamination of the product, causing septicemia in the recipient. Delayed immunologic transfusion reactions result from development of antibody that could shorten transfused RBC lifespan. Delayed non-immunologic transfusion reactions could result from the transfusion of blood contaminated with organisms like FeLV or FIV. Delayed non-immunologic reactions can be prevented through appropriate donor screening.

Footnotes:

Midwest Animal Blood Services Inc. 4983 Bird Dr. Stockbridge, MI 49285.

DMS Laboratories, Inc. 2 Darts Mill Road, Flemington, NJ 08822

Available through: Michigan State University Animal Health Diagnostic Laboratory, East Lansing, MI 48824.

Hydromorphone HCl Inj. USP. Abbott Laboratories, North Chicago, IL

Butorphanol tartrate, Forte Dodge Animal Health

Isoflurane USP. Abbott Laboratories, North Chicago, IL

Anticoagulant Citrate Phosphate Dextrose Adenine Solution, USP (CPDA-1) Blood Pack Unit. Baxter Healthcare Corp. Fenwal Division, Deerfield, IL 60015

Adsol Red cell Preservation Solution. Baxter Healthcare Corp. Fenwal Division, Deerfield, IL 60015

Blood Set. Abbott Laboratories, North Chicago, IL 60064

Hemo-Nate Filter, Gesco International, San Antonio, TX

References

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Giger U, Griot-Wenk ME, Bucheler J et al. Geographical variation of the feline blood type frequencies in the United States. Fel Pract 1991;19:21-27.

Giger U, Bucheler J, Patterson DF. Frequency and inheritance of A and B blood types in feline breeds of the United States. J Hered 1991;82:15-20.

Weinstein NM, Blais MC, Harris K et al. A newly recognized blood group in domestic shorthair cats: the MIK red cell antigen. J Vet Intern Med 2007;21:287-292.

Wardrop KJ, Reine R, Birkenheuer A et al. Canine and Feline Blood Donor Screening for Infectious DiseaseJ Vet Intern Med 2005;19:135–142.

Owens SD, Oakley DA, Marryott K et al. Transmission of visceral leishmaniasis through blood transfusions from infected English foxhounds to anemic dogs. J Am Vet Med Assoc 2001;219: 1076-83.

Howard A, Callan B, Sweeny M et al. Transfusion practices and costs in dogs. J Am Vet Med Assoc 1992;201:1697-1701.

Griot Wenk ME, Giger U. Feline Transfusion Medicine; Blood Types and their Clinical Importance. Vet Clin N Amer Sm Anim Pract 1995;25:1305-1323.

Hohenhaus AE. Blood banking and transfusion medicine. In: Ettinger SJ, Feldman EC eds. Textbook of Veterinary Internal Medicine. 5th ed. Philadelphia: W.B. Saunders Co. 2000: 348.