blood transfusion is used to treat signs of anemia caused by an
illness, surgery, toxicity, or trauma in dogs. It is aimed towards managing these symptoms by replacing red blood cells in the body so that proper oxygenation of organs can occur.
Blood transfusions are most commonly used to treat emergencies such as acute hemolysis or blood loss, but can also be used for chronic conditions such as immune-mediated hemolytic anemia. However, not all dogs diagnosed with anemia require blood transfusion. It is important to note that blood transfusions should be carried out in a veterinary clinic under the medical supervision of a veterinarian.
Importance of knowing the correct blood type:
Blood types (or groups) are determined by specific antigens found on the surface of erythrocytes. In humans, there is the ABO system of blood types, whereas animals
have varied blood types. Knowledge of
blood types in different species is of considerable significance as transfusion of incompatible blood wherein the donor animal has a different blood type from the recipient animal can result in severe hemolytic transfusion reactions that may even prove fatal in some instances.
Canine blood types:
There are 8 major blood groups in dogs, labeled as DEA (dog erythrocyte antigen)
1 to 8. The major antigens comprise of DEA 1.1 and DEA 1.2. Dogs can be positive for either (not both) DEA 1.1 or 1.2 or are negative for both. Only those dogs that are DEA 1.1 and 1.2 negative are susceptible to acute hemolytic transfusion reactions as they don’t have naturally occurring antibodies. In such cases, a reaction is only visible once the dog has been sensitized through exposure to DEA 1.1 or 1.2 positive blood (antibody production takes 7-10 days after exposure). The average lifespan of compatible transfused erythrocytes is about 21 days in dogs.
Selecting the right donor
Whole blood is collected from a donor animal for blood transfusion purposes into a blood bag containing citrate phosphate dextrose as the anticoagulant. Donor animals should be selected with care, and strict attention should be paid to the blood collection technique to maintain sterility at all times. You can use a single blood transfusion bag in cases that only require the collection of whole blood. Double, triple and quadruple blood bags can be used to produce and separate components within a germ-free closed environment.
A major problem that arises with blood transfusion is finding a reliable donor animal. Many private veterinary practitioners may use their own animals or donors or provide a list of outpatient donors. However, the high cost associated with blood transfusions makes it a viable option only for private veterinary clinics or hospitals.
It is essential to ensure that their donor animals are healthy and have normal hemograms, biochemical panels, fecal examinations and urinalysis. They must be fully vaccinated and checked for a variety of infectious diseases such as Babesia, Ehrlichia and Toxoplasma.
They should also be heartworm negative and on heartworm preventive medication. Large-breed animals are often preferred to their smaller counterparts as large amounts of blood can be drawn from them by administering minimal sedation. The Mughal Hound and Rajapalayam breeds are the most commonly used blood donors. It is recommended to blood type all preferred donors. The best canine blood donors are DEA 1.1, 1.2, and 7 negative.
Blood Collection technique
Commercially available human blood collection bags can be used for blood donation in dogs. These bags have the capacity of collecting up to 450 ml of blood. The aseptic technique should be used while collecting blood from donor animals. This means that the site should be clipped, surgically scrubbed and sterile gloves worn during the process of blood collection. The jugular vein is the most common site used for donation in all animals. Vein puncture should be clean with rapid blood flow to minimize platelet activation. After collection, direct pressure should be applied to the site to attain homeostasis. In some cases mild vacuum pressure may be applied to facilitate blood collection. Sedation should be avoided if possible, particularly if the blood is to be used for platelets. However, under certain circumstances, general anesthesia may be required which appears to have little effect on the quality of the blood product. The blood should be immediately refrigerated and stored in the refrigerator until further use for transfusion or separation into components.
Transfusion reactions are divided into two categories: immunological and non-immunological. The most common reactions to transfusions are fever, vomiting and facial edema which are mild. More severe reactions include intravascular hemolysis, shock and dyspnea. The most common type of reaction is fever, followed by vomiting (mostly in dogs given packed red blood cells). Allergic reactions may also crop up in dogs given packed red blood cells or plasma.
In general, treatment of transfusion reactions is symptomatic and logical. Firstly, if a reaction develops, the transfusion should be stopped immediately (in case of a severe reaction) or slowed (for milder reactions). The animal should be treated symptomatically if showing signs of shock. In such cases, fluid therapy at shock doses and corticosteroids should be initiated. If showing signs of an anaphylactic reaction, corticosteroids and/or antihistamines can be administered. Currently, it is not recommended to administer pre-transfusion corticosteroids and/or antihistamines to try and prevent an allergic-type transfusion reaction. These reactions are generally mild and can be minimized by slow transfusion rates and by not mixing multiple bags from different donors. If an animal is known to have had previous hypersensitivity reactions, then pre-medication with anti-allergic drugs is indicated.
Blood transfusion in dogs is effective in restoring blood cells lost to anemia and alleviating the symptoms caused by blood loss. The effects of transfusion are not permanent; therefore, it is essential to address the root cause of anemia in order to have a more lasting impact on the dog’s health. Treatments related to blood transfusions such as plasma transfusion and platelet transfusions are also available as additional transfusions to boost clotting factors and platelets; however, they cannot be used on their own in place of a blood transfusion.
Prevention of Blood Transfusion in dogs:
The circumstances leading to blood transfusion in dogs are varied, and some can also be prevented through regular health check-ups. Certain immune disorders such as immune-mediated anemia are unfortunately not preventable, but once diagnosed can be managed with proper medication. Also, it is difficult to prevent emergencies arising out of a significant loss of blood or cancers resulting in anemia. However, anemia arising due to flea and tick infestation can be prevented. Ensuring that fleas and ticks do not bite your dog can prevent anemia caused by tick-borne diseases. In addition to this, making sure that your dog is free of internal parasites, such as intestinal worms, also keeps anemia at bay. It is also vital to ensure that your dog does not have access to foods such as onions and garlic to prevent anemia that may occur due to toxicity.
The most common risk associated with blood transfusion in dogs is the potential for the development of an acute reaction. Your dog will be monitored after the transfusion to ensure that no reaction occurs. All signs of a reaction need to be managed immediately. Other risks factors associated with blood transfusion include sepsis from contaminated blood and the spread of blood-borne diseases (parasitic and viral) from the donor to the recipient. Blood transfusion in dogs provides rapid, life-saving assistance by rapidly managing the conditions resulting in anemia.
*Dr Kumar Ravi is a practicing veterinarian Indirapuram pet clinic Ghaziabad. He has been practicing for 15 years.