Blood is the body fluid that caries essential substances such as oxygen and nutrients towards the cells and caries metabolic wastes away from those same cells.
Normally whole blood is composed of blood cells and blood plasma and some essential nutrients and hormones.
Why to transfuse blood?
Whenever there is acute loss of blood from body or any other abnormality due to which blood volume decreases down to certain value from its normal range, there is always a need of blood transfusion to save life of that animal. Acute loss of blood results into development of anemia, a life threatening condition.
There are three major types of anemia Haemolytic anemia, Haemorrhagic anemia and Aplastic anemia from which first two types develop due to acute loss of blood. Typical example of Haemolytic anemia in animals is Porphyria and any acute injury leads to Haemorrhagic anemia, when animal is unable to produce new RBC’s that condition is called Aplastic Anemia.
Other than anemia blood transfusions are done in kidney patients, cancer patients, patients having some parasitic, bacterial, viral infections and auto-immune problems. Blood may also be given to the animal having low platelets, but there is one precaution in such transfusion is that, platelets cannot be stored readily from cats and dogs, so if blood is needed for platelets, take from donor and give to recipient straight away.
In addition to this, it should be keep in mind that platelets number rise quickly after haemorrhage, so platelets replacement is rarely required, but may be of value in Thrombocytopenia.
Diagnose through clinical signs
Animals suffering from acute anemia show some typical clinical signs, those are :-
- Lethargy and exercise intolerance, because decreased number of RBC results into decreased oxygen carrying capacity.
- Pale mucous membrane, due to decreased number of RBC.
- Decreased appetite.
When these signs are observed in dogs, veterinarian must go for lab tests.
Diagnose through lab tests
Mostly Complete blood count (CBC) performed in lab and checked for two findings, explained below to diagnose the degree of anemia.
- Packed Cell Volume (PCV) or Hematocrit (HCT)
Normally dog’s blood have 45%-54% Red blood cells, if PCV below than 45% animal is considered to be slightly anemic, as the value drops down degree of anemia increases and when PCV drops below 25% dog needs blood transfusion.
- Haemoglobin (Hb g/dl)
Normal range of Hb in dogs is 12-18g/dl, when its value drops down below 10g/dl dog needs blood transfusion.
Collection and Storage of Blood from Donor
Collection and storage should be done aseptically, in commercially available blood bags containing the proper amount of anticoagulant for a unit (500ml). Anticoagulant of choice is citrate phosphate dextrose adenine (CPDA-1) 1ml/9ml blood.
Heparin as anticoagulant should not be used in blood bags because
- It has longer half-life in recipient
- It causes platelet activation
- heparinized blood cannot be stored
- It alters the capillary membrane permeability.
Blood can be collected from Jugular vein or Cephalic vein with the help of 18-20 G needle, while collecting the blood, shake the bag regularly and gently to mix blood and anticoagulant. 10-20ml/kg body weight blood of a dog can be withdrawn in single collection and blood collection can be repeated after 28 days from the same donor. Blood can be stored at 4⁰C for 4 weeks.
The blood type system present in dogs is called Dog Erythrocyte Antigen (DEA 1.1) positive or negative. In ideal condition before transfusion blood should be cross matched but in dogs first blood transfusion in life can be done without cross matching because dog’s blood don’t have any kind of antibodies so that blood of any type can be transfused, but cross matching is very important in subsequent transfusion because then dog’s blood have particular antibodies against either of the blood type.
Transfusion of blood to recipient
Blood transfused to recipient dog through cephalic vein, there are certain methods to calculate the required volume of blood to be transfused 1.10ml to 40ml/ kg blood can be transfused in dogs, depending upon the degree of anemia. For example a dog having weight 25 kg can bear the transfusion of 250-1000ml blood.
2.To calculate the exact volume of blood needed by patient to meet its normal PCV range, a useful formula is
Volume= (Patient wt. in kg × Desired PCV-Patient PCV ) × 90
By which rate blood is given to the recipient is called Transfusion Rate, and it is very important to transfuse blood at safer rate, so that any transfusion reaction can be monitored and handled easily.
Initially blood is transfused at the rate of 0.2ml/kg/hr or 10 sec/drop, for 15 minutes. If no transfusion reaction has been observed, increase the rate upto 10ml/kg/hr or 2-3 sec/drop.
- Avoid excessive heating, as fibrinogen precipitates at high temperature and auto agglutination occurs.
- Transfusion results in immediate improvement in the condition of the recipient but the beneficial effects are short lived because RBC of first transfusion survives only for 7-10 days in recipient, and RBC of second transfusion survives only for few hours to 2 days only.
- Use local anaesthetics while collection and transfusion.
- Avoid the use of solutions containing Ca, because Calcium will deactivate citrate and clots will be formed in recipient.
Severe reactions and their treatment
- Pyrogenic reactions may be seen and temperature increases, so administer antipyretic drugs
- Haemolysis may occur due to presence of host antibodies, administer diuretics and fluids.
- If reaction is severe, stop the transfusion immediately and give Normal Saline I/V.
- Antihistaminic drugs can be given in case of allergic reactions.
- If over hydration occurred, administer diuretics.