May 2025
In this VETgirl online veterinary continuing education blog, Lexi Dickens, BS, LVT, RVT, VTS (ECC) covers essential canine and feline blood donor screening considerations to ensure donor and recipient safety. Learn about eligibility criteria, infectious disease testing, and best practices for maintaining high-quality blood products in veterinary transfusion medicine. Read on to enhance your transfusion protocols!

Canine and Feline Blood Donor Screening Considerations

By Lexi Dickens, BS, LVT, RVT, VTS (ECC)
Senior Patient Care Training Coordinator, BluePearl Pet Hospital, Cary, NC

Introduction

Blood product administration is often considered a life-saving measure for recipients; however, no transfusion is free of risk. Many may consider immunologic or non-immunologic transfusion reactions as the only risk to recipients; however, transmission of blood-borne pathogens or other infectious agents should not be overlooked. All donors should go through comprehensive screening throughout their donor career to minimize the spread of pathogens or infectious agents.

(Image courtesy of Lexi Dickens)

It is also our responsibility to ensure the safety of the donors. This includes not only physical safety during donations, but also overall wellbeing and ensuring every decision is made with their best interest in mind. A rigorously detailed initial and annual screening process helps to maintain safety for donors and recipients alike.

Initial Eligibility Criteria

Most blood banks follow a relatively similar protocol for initial screening. Qualification criteria between canine and feline donors can vary slightly. When assessing inclusion criteria, donor safety and well-being should be considered a top priority.

Inclusion factors that are not species specific include remaining up to date on all core vaccines, use of year-round flea, tick, and heartworm prevention, and no history of a previous transfusion. Most blood banks also require donors to be between 1 and 8 years of age.1,2 Potential donors should be friendly and have a good disposition in a clinical setting. If a potential donor is fractious, unfriendly, or not amenable to restraint, exclusion from the donor program should be considered.

Feline donors should be indoor only as outdoor exposure significantly increases the risk of disease or illness that could be passed along to recipients. Weight restrictions should be meticulously followed as blood collection volumes are based on body weight. Many donor programs have a minimum lean body weight of 10 lb (4.5 kg) for feline donors.2 This allows a typical donation volume of 10-12 ml/kg.

Canine donors have a wider eligible weight range depending on what size unit the team plans to collect. A typical donation for a canine patient may range from 11-19 ml/kg. Donors that are 50 lb (22.7kg) or more are ideal as they can donate a standard 450 ml unit.1 However, the ability to source smaller collection bags (250-300ml) allows programs to consider slightly smaller donors ranging from 40-49 lb (18.1-22.2 kg).

Other screening criteria might include whether the patient is on a raw diet, breeding status, or possible chronic medication use. Decisions on factors such as these would be at the discretion of the blood bank, hospital, or overseeing veterinarian as there are no current consensus statement on these factors.

Screening Requirements

If potential donors meet the initial eligibility criteria, the next steps include a comprehensive physical exam and blood analysis. Evaluating the potential donor’s compliance during the physical exam can help ensure that they have a good disposition. Abnormalities on physical exam that might warrant exclusion may include severe dental disease, heart murmurs that have not been evaluated by a cardiologist, or other signs of illness.

Donors should undergo a comprehensive blood analysis including at least a complete blood count and serum biochemistry. Additional screening that may be performed based on individual blood bank criteria include urinalysis, fecal exams, and thyroid panels. Abnormalities on these panels may warrant exclusion or further testing. Full blood analysis in compliance with the individual blood bank requirements should be completed at least annually.1-3

(Image courtesy of Lexi Dickens)

All donors should have a one-time blood typing performed during initial screening. At minimum canine donors should be typed for dog erythrocyte antigen (DEA) 1. Some blood banks may type for DEA 4, 5, and 7, however there is limited evidence showing clinical significance at this time. Depending on the potential donor’s breed, additional testing may be considered at the discretion of the blood bank and overseeing veterinarians such as Dal antigen testing or von Willebrand testing.1 Feline donors are tested to determine if they are type A, B, or AB. Due to inability to currently test for Mik antigen it is suggested to crossmatch feline patients prior to transfusion to avoid adverse reaction.2

(Image courtesy of Lexi Dickens)

Consensus statements from organizations such as the American College of Veterinary Internal Medicine (ACVIM) guide screening for blood-borne pathogens. Donors should undergo initial and, at minimum, annual infectious disease testing. The ACVIM Consensus Statement provides guidance for minimum as well as optimal screening practices, including vector-borne and non-vector-borne diseases. Minimum testing for vector-borne pathogens should include polymerase chain reaction (PCR) tests for Anaplasma, Babesia, Bartonella, Ehrlichia, Leishmania, Mycoplasma, and Dirofilaria immitis.1 For feline donors, minimum PCR testing for non-vector-borne pathogens includes feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV). The Consensus Statement also addresses other considerations when screening donors, such as additional testing based on travel to regions with endemic disease as well as additional testing for patients that remain intact.3

Continued Screening

For voluntary or community donors, the owners should fill out comprehensive screening paperwork at every donation to ensure there are no significant changes. This screening can ensure that patients remain up to date on core vaccines, preventatives, are not on any disqualifying medication, have not traveled to any endemic areas, and remain eligible and safe for donation. This also allows a double check system to ensure the patient has not fallen behind on annual screening lab work.

For donors that reside in a colony there should be a double check system in place to ensure there have not been any significant changes with the donor and they have not fallen behind on any vaccines, preventatives, or screening lab work.

Regardless of donor type, a complete physical exam should be performed prior to every donation to ensure there are no new concerns that may put the donor or the recipients at risk. After the comprehensive physical exam, donors should have at least a packed cell volume (PCV) checked to ensure they are at a safe level to donate.1

Having a detailed standard operating procedure (SOP) that is followed by all blood bank staff helps ensure the safety of donors and recipients. SOPs for initial screening, day of donation screening, and donations can help teams maintain safety and efficiency.

(Image courtesy of Lexi Dickens)

Conclusion

Blood products play a crucial role in veterinary medicine, allowing teams to offer lifesaving treatment. The safety of these products depends heavily on careful donor selection and comprehensive screening, while also safeguarding the health and wellbeing of the donors. By adhering to the industry standards and consensus statements, teams can help ensure that they are maintaining safe and ethical practices while producing high quality products.

(Image courtesy of Lexi Dickens)

References

  1. Yagi K, Bean BL. Canine donor selection. In: Yagi K, Holowaychuk M, editors. Manual of veterinary transfusion medicine and blood banking. Wiley Blackwell; 2016. p. 189-198.
  2. Russo C, Humm K. Feline donor selection. In: Yagi K, Holowaychuk M, editors. Manual of veterinary transfusion medicine and blood banking. Wiley Blackwell; 2016. p. 212-222.
  3. Wardrop KJ, Birkenheuer A, Blais MC, et al. Update on canine and feline blood donor screening for blood-borne pathogens. J Vet Intern Med. 2016; 30(1):15–35

  1. kendra berube says:

    Is there any added information on the different visual scenarios regarding what is a positive or negative result when using the Rapidvet Crossmatch Major kit. I find that not all tests are as perfect as the picture example in kit and I want to make sure I am reporting the correct result. Any help or direction?So far in my online search the same picture is used rather than other possibilities
    Thanks
    Kendra

  2. Lexi Hansen says:

    Hi Kendra,

    That is a great question! Patients that have received multiple transfusion or patients that are suspected to have certain traits such as the canine Dal antigen or feline Mik antigen can often display crossmatching results that don’t resemble the perfect pictures. The one thing that we always want to see with the RapidVet Major Crossmatch kits is that the negative control demonstrates RBC collection at the bottom and the positive control demonstrates RBC collection at the top of the column. As far as assessment of the reaction tube ideally the RBCs should collect in the bottom like the picture above. If the majority of the RBCs collect at the top half of the reaction tube we would not want to use that unit/donor. Ideally the majority of the RBCs should be in the bottom half of the gel. Clinically I have been in situations where a patient that has received multiple transfusions (e.g. IMHA) may need to be crossmatched to multiple units/donors. For canine patients we may be faced with the decision of selecting the unit that shows the smallest reaction (has the most RBCs collection in the bottom half of the gel). Of course in theses situations the owners should be informed about the concern for a reaction and the DVM would need to assess the clinical situation and consider the consequences of giving a transfusion versus withholding a transfusion to find a more compatible unit. For our feline patients as with most things I feel we are a bit more conservative. If they are incompatible with a unit we are less likely to administer it. Unfortunately we often find ourselves in what I call a “gray” area where we have to weigh the pros/cons of a decision and make the most educated decision based on the full clinical picture.

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