Blood banking (Proceedings)

As veterinary medicine progresses, so does our ability to provide advanced services and quality care. One area this is most evident, is the constantly changing practices of transfusion medicine. With that said, we must continually evolve our blood banking protocols to meet the standards of quality control needed to uphold patient safety and transfusion efficacy. Blood banking can be done in a multitude of ways, i.e. a designated “hospital cat” who donates on an as needed basis, on to an advanced commercial blood bank.

Blood banks

There are two types of blood banks, commercial and volunteer based. Commercial blood banks consist of a closed colony of donors that have minimal exposure to infectious diseases. These donors have been pre-screened for blood borne diseases. Due to the ability to closely monitor the donors, donations are taken every 3-4 weeks. Volunteer based blood banks rely solely on the donors' owner to provide the opportunity for blood donation. These donors are also pre-screened for blood borne diseases. The risk for disease exposure is increased with volunteer programs, which reinforces the necessity for screening standards. Donations with a volunteer blood donor are typically taken every 3-4 months.  It is also important to reward volunteer donors with an incentive, such as complimentary lab work or food, for donating. In addition to incentives for donating, it is important to remember our donors once they become retired blood donors. Sending a retired donor a gift basket and card thanking them for their life-saving services is another way to convey how important volunteer donors are to veterinary medicine.

Donor screening

It is important to consider disease transmission, blood type, health status, age, and attitude when screening for potential donors. Donor requirements and screening protocols are listed below, and broken down by species.

Canine: Between 1-7 yrs (retired at 8 yrs)

• Over 50 lbs

• Current on vaccines and year round heartworm prevention

• Friendly and calm disposition, easily restrained

• Full chemistry panel, CBC, heartworm test, and average HCT 40%

• Full blood typing (DEA 1.1, 1.2, 4, & 7)

• Brucella, Babesia, Leishmaniasis, Erlichiosis, Anaplasmosis, Hemoplasmosis, Bartonellosis (Vector borne disease testing varies with region)

Feline: Between 1-7 yrs (retired at 8 yrs)

• Over 10 lbs

• Current on vaccines and year round heartworm prevention

• Normal echocardiogram

• Indoor only

• Friendly and calm disposition is ideal

• Full chemistry panel, CBC, heartworm test, and average HCT 30%

• Blood typing (A, B, or AB)

• Felv/FIV, Mycoplasma haemofelis, Anaplasma, Bartonella, Cytauxzoon felis, Erlichia (testing varies with region)

Blood typing

Given the donor screening protocol above, it is important to be familiar with both canine and feline blood typing. Recognizing how canine and feline blood types can be utilized in the blood bank can maximize the donor pool. There are 13 canine blood groups, and blood type considerations vary with region (Dogs, unlike cats, acquire antibodies through exposure.). The typing sera we most commonly use are DEA 1.1, 1.2, 4, & 7. D.E.A. (or Dog Erythrocyte Antigen) refers to antigens on the surface of the red blood cell. These antigens are responsible for initiating hemolytic transfusion reactions. Thus it is important to type donor and recipient before transfusing, and cross match when indicated. D.E.A. 1.1 is most antigenic, and recipients can easily be screened “in-house” using RapidVet card typing and Alvedia typing kits.  Donors should be screened for the typing sera listed above at an outside lab to ensure accuracy. The “Universal” type is considered D.E.A. 1.1 & 1.2 negative, 4 positive, and 7 negative. Although most dogs are D.E.A. 1.1 positive, as long as they are 1.2 negative, 4 positive, and 7 negative, they can be used in the donor pool. This increases your available donors greatly, and also reinforces recipient typing to avoid transfusion reactions. Cats, however, have naturally occurring antibodies (similar to humans) against other blood types. Thus it is extremely important to type donor and recipient, and ideally cross match prior to every transfusion. It is these antibodies that are responsible for fatal acute hemolytic transfusion reactions. Screening for Types A, B, and AB are imperative in the donor screening process. Though type B cats are rare, an increase has been seen. Feline donor typing should also be performed at an outside lab to ensure accuracy. Recipient typing can be done using Alvedia testing kits, as well as  RapidVet-H IC and RapidVet typing cards along with RapidVet crossmatching kits.

The donation process

It is important to ensure donor safety and compliance during the donation process. It should always be a positive experience for the donor. That said, the materials you will need are listed below:

• Pheromone spray (such as Adaptil)

• Bedding

• Gram Scale

• Blood collection system

• Alcohol and scrub prep

• Bandage material

• Clippers

• Line strippers

• Metal clamps

• Anesthesia machine/monitoring equipment/ET tubes/heat support/crystalloid (for feline donation)

• Reward for donor post donation

Canine donation process

Canine donors should have a TPR, weight, physical exam and CBC before each donation (with full lab work and heartworm screening annually). Place blood collection bag on gram scale and zero out. Donor is laid in lateral recumbancy (on previously pheromone sprayed bedding), extending the head for visualization of the jugular vein (It is ideal to alternate jugular veins with each donation). Have assistant hold off the jugular vein, and once visualized clip a 2x2 inch area for venipuncture. Use a three scrub prep in the shaved area. Insert needle from collection bag into the jugular vein, and collect approximately 475 grams (maximum donation is 22ml/kg). Be sure to gently agitate the collection bag during donation to adequately mix anticoagulant and blood. Once the desired amount has been collected, clamp line, remove and cap the needle. Apply a neck wrap, and leave in place for approximately 1 hour. Reward donor with a treat or toy to reinforce the positive aspects of the experience. It is imperative to monitor the donor closely post donation for any signs of hypotension, weakness, and pale mucous membranes. It is also suggested to offer a small meal after donating.

Feline donation process

Feline donors should also have a TPR, weight, physical exam, and CBC before each donation (with full lab work and heartworm screening annually). It is highly suggested that cats be anesthetized for blood donation. Have an anesthetic machine, monitoring equipment, heat support, and endotracheal tubes prepared. It is suggested to mask the cat down to allow intubation, vs. a tank method of anesthetizing. This will vary however, with donor compliance. Once the donor has been intubated, have assistant monitor vitals during donation. Similar to dogs, hold off and visualize the jugular vein, being sure to alternate jugular veins with each donation. Shave a 2x2 inch area and use a three scrub prep at the site. Using the needle on the collection system, insert into the jugular vein. Collect approximately 50mls (maximum donation is 15ml/kg) while mixing gently with anticoagulant. Collection amount varies with the type and amount of anticoagulant and preservative used.  Remove needle once collection is complete, cap needle and place bandage on neck. Leave neck wrap in place for approximately 1 hour. It is suggested to administer SQ fluids, equivalent to the volume of blood taken from the donor. Recover from anesthesia and monitor closely until fully awake. It is recommended to offer a small meal after donation.

Blood components and separation

To maximize blood products and ensure transfusion safety, component therapy is strongly relied upon. Separation of blood products after donation, along with proper handling and storage is necessary. Once you have collected your blood, it is then important to make aliquots using line strippers and metal sealant clamps/heat sealant. Aliquots will allow for future cross matching without spiking a unit. Once aliquots are made, blood product separation is achieved using a centrifuge at 5,000 rpms for 8 minutes. This will separate the unit into packed red blood cells and plasma. The use of a blood product separator stand will remove the plasma from the unit, creating a unit of prbc's and plasma. Plasma aliquots should also be made for future cross matching.  Depending on the preservative used, prbc's can typically be stored 21-35 days at 1-6? C. Plasma (if frozen within 8 hours if collection) can typically be stored for 1 year at  -18? C, and maintain coagulation factors. This is then labeled fresh frozen plasma. If plasma is not frozen within the allotted amount of time, is thawed and re-frozen, or has been frozen greater than 1 yr it is, then labeled as frozen plasma and no longer has viable coagulation factors. Frozen plasma can be stored for an additional 4 years. If whole blood is desired, do not centrifuge unit, and it will remain fresh whole blood for 6-8 hours after collection. Fresh whole blood not only contains red blood cells, but also viable platelets, coagulation factors, albumin, and plasma proteins.

Complications and contraindications

Complications can arise when maintaining a blood bank. What is important, is how we address these problems. Pre-donation screening is one avenue to prevent complications and contraindications. This can help detect any changes lab work, health, and well being in the donor. This is especially important when conversing with the owner of the volunteer donor. Be sure to ask if there are any health changes, new medications, or behavioral changes as it may be contraindicated to donate at that time. These questions ensure the safety of the transfusion recipient. Also, when a donor is not cooperative, or apprehensive regarding the donation process, it can be beneficial to administer mild sedation. This not only eases the donor, it allows for a smooth collection. When choosing a sedative, it is important to consider the effects it will have on the cardiovascular system. Butorphanol and midazolam can typically be safely used due to their cardiorespiratory sparing effects. Additional problems that arise during donation are inadequate collection, in which case the unit should not be salvaged. Inadequate collection can lead to citrate toxicity.

Recent findings

There are some recent findings that cause us to take note, and possibly change blood banking protocols in the future. Leukoreduction filters, though still being studied, may decrease the risk of non-hemolytic febrile transfusion reactions. This is one of the most common transfusion reactions seen. The theory is that by removing donor leukocytes, there is a decrease in markers of inflammation. Leukoreduction filters are cost prohibitive however, and require additional research.

The DAL antigen is a recently discovered dog erythrocyte antigen and requires attention when transfusing Dalmations in particular. This antigen exists commonly in most dogs, but is not found in some Dalmations. Thus transfusing a dog that does not have the antigen, with the DAL antigen can lead to severe transfusion reaction. It is strongly recommended to cross match any Dalmation before transfusion.

MiK is an antigen that has been recently identified in cats. MiK is found to be present in most cats; however some have naturally occurring antibodies against this antigen. If a cat has naturally occurring antibodies to MiK, and is transfused with this antigen, hemolytic transfusion reaction will occur. The importance of cross matching each cat prior to transfusion must be stressed.

When starting up a blood bank, or designating a hospital pet for donation, it is imperative that appropriate screening be performed. It is also important to be aware of new technology and findings in regard to blood banking and transfusion medicine. In order to maintain a productive, prosperous, and efficient blood bank, strict protocol and standards must be met.