You are likely familiar with the concept of donating blood for human medical patients, but did you know that blood transfusions are also used in the veterinary field? Cats, dogs, and other small animal species can all benefit from blood transfusions when experiencing anemia caused by injury or illness.
Quick Overview: Cat Blood Transfusions
Cat Blood Transfusion Procedure: How Does it Work?
The first step in a blood transfusion is pre-transfusion testing. There are a number of tests that are performed prior to a blood transfusion, in order to ensure that the donor and recipient are a match.
First, your veterinarian will probably determine your cat’s blood type.
There are three blood types in the feline blood group system: Type A, Type B, and Type AB. Type A is the most common blood type and it is found in 95% of Domestic Shorthaired cats. Type A blood is also common in Siamese, Burmese, and Russian Blue cats. Type B blood is the predominant blood type in Persians, Abyssinians, Devon Rexes, Scottish Folds, Maine Coons, and Sphinxes. Type AB blood is rare, but can occur in cats of any breed.
There is no “universal donor” in cats.
Cats with Type A blood should only receive blood from a Type A donor and cats with Type B blood should only receive blood from a Type B donor, because cats with Type B blood have anti-A antibodies and cats with Type A blood have anti-B antibodies. Cats with Type AB blood are regarded as “universal recipients,” because they can receive any blood type.
Once your cat’s blood type has been identified and a suitable donor has been found, your veterinarian will perform a test called a cross-match to assess donor/recipient compatibility.
This involves mixing small quantities of your cat’s blood and donor blood, then observing the mixed samples under the microscope.
This test can help identify donor/recipient blood pairings that are associated with a high risk of reactions. In some cases, even two cats of the same blood type will show evidence of reaction on cross-matching. If this occurs, a new donor may need to be identified.
After blood typing and cross-matching, your veterinarian will collect whole blood from the donor cat. (If no suitable in-house donor is available, your veterinarian may obtain blood from a blood bank instead.)
The quantity of blood collected depends on a number of factors, including your cat’s size, the donor cat’s size, and the severity of your cat’s anemia. This blood donation is collected into a special bag or bottle, which contains anticoagulant to prevent clotting of the blood.
After collection, this bag or bottle of blood will be connected to a fluid line, with an in-line filter to remove any blood clots that may have formed despite the anticoagulant. The fluid line will be inserted into an intravenous catheter, placed in your cat’s leg.
Blood transfusions are typically given slowly, over a period of one to three hours. A slow administration rate provides ample opportunity for the veterinary team to monitor your cat and adjust treatment if necessary. After the transfusion, your cat will likely remain hospitalized for at least 24 hours, in order to allow for post-transfusion monitoring.
Why a Cat May Need a Blood Transfusion
Cats may require a blood transfusion for a variety of reasons. Any time that a cat experiences a significantly low red blood cell count, a transfusion may be considered. In a healthy cat, the Packed Cell Volume (PCV), or the percentage of the blood that is composed of red blood cells, is 25-45%. Most veterinarians will recommend a blood transfusion when a cat’s PCV falls below 10-15%, although this decision is also influenced by the cat’s clinical appearance.
There are a number of possible reasons that a cat can experience a loss of red blood cells, or a decrease in PCV.
These causes can be thought of in three broad categories: decreased red blood cell production, increased red blood cell loss, or increased red blood cell destruction.
Red blood cells are produced within the bone marrow. Any disease that affects the bone marrow can interfere with the production of red blood cells, leading to anemia. The lifespan of a normal feline red blood cell is only about two months, so without a constant supply of newly-produced red blood cells to replenish dying red blood cells, anemia can and will develop.
Bone Marrow Disease
The kidneys are also involved in triggering the production of red blood cells, so kidney disease may also lead to a decrease in red blood cell production.’
Red blood cell loss occurs due to bleeding. While this bleeding may be caused by trauma, anemia is more commonly caused by gradual, chronic blood loss.
Common causes of bleeding in cats include gastrointestinal bleeding (ulcers or bleeding tumors), bleeding tumors elsewhere in the body, severe flea infestation, and blood clotting disorders. Increased bleeding can overcome the body’s ability to create new red blood cells, resulting in anemia.
Red blood cell destruction refers to the destruction of red blood cells within the circulation. This destruction is caused by immune-mediated disease, in which the cat’s body begins to recognize its own red blood cells as foreign.
Immune-mediated disease may be caused by a primary autoimmune disease, or may occur in response to another trigger such as cancer, a red blood cell infection, or a drug reaction. Cats with increased red blood cell destruction may become anemic if the rate of red blood cell destruction exceeds the rate of new red blood cell production.
Cat Blood Transfusion Success Rate
A research study performed in 2004 examined the survival rates of 91 cats receiving blood transfusions. In this study, 84% of cats were still alive one day after their transfusion and 64% of cats were still alive 10 days post-transfusion. None of the deaths were attributed to a transfusion reaction; all were a result of the cat’s underlying disease.
Cats requiring a blood transfusion are typically very ill. By the time a cat’s PCV is low enough to require a blood transfusion, the cat is likely to die without that life-saving care. A blood transfusion can dramatically improve the prognosis for a cat with severe underlying disease. However, the impact of a transfusion is largely dependent on the cat’s underlying disease.
A cat who is experiencing life-threatening anemia due to a severe flea infestation will likely have a good prognosis if a blood transfusion is given and appropriate flea treatment is administered.
A cat with cancer affecting the bone marrow, however, may experience brief relief of weakness and lethargy from a blood transfusion, but the cat’s long term survival will depend upon the ability to control the underlying bone marrow cancer.
Reactions to Blood Transfusions
There are two different types of transfusion reactions that can occur in cats: immunologic and non-immunologic.
Immunologic reactions are those reactions that we first think of when we consider transfusion reactions; they involve the body’s immune response to receiving foreign red blood cells and can resemble an allergic reaction.
Non-immunologic reactions, in contrast, are not caused by an immune reaction. Examples of non-immunologic reactions include volume overload (a response to the fluid volume that is administered during a blood transfusion, which can place a strain on the heart and lungs), infectious disease transmission, or bacterial infection due to contaminated blood products.
Most transfusion reactions occur during the first 48 hours after receiving a transfusion.
The signs and severity of these reactions may vary significantly, ranging from a mild allergic reaction to a more severe anaphylactic reaction.
Signs of an Adverse Reaction to a Blood Transfusion
The most common clinical sign of a transfusion reaction is a fever, which indicates an immune response to the foreign red blood cells. In some circumstances, this reaction may progress to include hives, skin inflammation, itching, vomiting, and/or diarrhea. Pale gums may also develop, in addition to an elevated heart rate and/or respiratory rate. If signs of a transfusion reaction are noticed during a blood transfusion, your veterinarian will immediately stop the transfusion.
In some cases, an immunologic transfusion reaction may involve the breakdown of the transfused red blood cells. The body’s immune system recognizes these cells as foreign and attacks them, causing breakdown of the red blood cells, or hemolysis.
Cats with a hemolytic reaction may develop icterus, also known as jaundice. They may develop a yellow discoloration of the gums or the whites of the eyes, caused by red blood cell breakdown products.
Regardless of whether the reaction occurs during or after the transfusion, your veterinarian will administer treatments to halt the reaction.
These treatments may include antihistamines, corticosteroids, and/or epinephrine, depending on the severity of the reaction. Your cat may also require intravenous fluids, to help support circulation and maintain blood pressure.
These treatments may be short-lived, or your cat may be discharged on a prolonged course of immunosuppressive drugs to prevent further reactions until the red blood cells have served their purpose and been cleared from circulation.
It’s important to note that most transfusion reactions can be corrected with medical care. While life-threatening reactions can occur, the 2004 feline transfusion study did not find any evidence of life-threatening transfusion reactions in the 91 cats included in the study.
Veterinarians carefully balance the risks and benefits of blood transfusions, only recommending them for those cats in which the risk of untreated anemia exceeds the risk of a significant transfusion reaction.
Recovering From a Blood Transfusion
Recovery from a blood transfusion depends largely on the underlying disease responsible for the anemia. In most cases, you will notice an immediate improvement in your cat’s condition after the blood transfusion, because restoring normal numbers of red blood cells will improve your cat’s oxygen circulation and overall energy levels.
Post-transfusion care will depend on your cat’s underlying condition. Your veterinarian may prescribe antibiotics to treat an underlying infection, or corticosteroids if your cat has an immune-mediated disease. Your cat may also need to wear an e-collar (cone) if there are wounds or sutures that your cat may traumatize.
Cat Blood Transfusion Cost
The cost of a feline blood transfusion may vary significantly, depending on the cat’s overall condition, the volume and quantity of transfusions that are required, and the side effects that may or may not develop.
Most feline blood transfusions are performed at specialty hospitals, in order to ensure that cats receiving a transfusion can receive necessary 24-hour monitoring. The cost of a feline blood transfusion may range from $500-2,000, although costs may be even higher in critically ill cats or those that experience complications associated with their blood transfusion.
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Blood transfusions can be a life-saving treatment for cats with severe anemia. Although the procedure is not entirely risk-free, appropriate pre-transfusion testing can help minimize risk while still providing maximal benefits for anemic cats.
Frequently Asked Questions
Can cats have blood transfusions?
In cats with severe anemia, blood transfusion can be a life-saving procedure. These transfusions are administered similarly to blood transfusions in humans; the same basic principles of transfusion medicine apply, although there are differences in blood types.
Where do they get blood for cat transfusions?
Most feline blood transfusions involve the use of blood collected from a donor cat. Blood substitutes, such as Oxyglobin®, are also available and may be used when a blood donor is not available.
How long is a cat blood transfusion?
The duration of a blood transfusion varies, based upon the volume of the transfusion and the cat’s medical condition. In general, most transfusions are given over a period of one to three hours.
What cat blood type is considered the universal donor?
There is no such thing as a universal donor in feline transfusion medicine. Cats naturally develop antibodies against the blood antigens that they lack.
How much does a blood transfusion cost for a cat
The cost of a feline blood transfusion may range from $500-2,000, although costs may be even higher in critically ill cats or those that experience complications associated with their blood transfusion.