Blood transfusions

Blood is essential for life! It delivers necessary substances such as nutrients and oxygen to the cells as well as transporting metabolic waste products away from the cells. It is made up of blood cells suspended in blood plasma. Plasma is mostly water, but it also contains proteins, glucose, mineral ions, hormones, carbon dioxide and blood cells. The blood cells are mainly red blood cells, white blood cells and platelets. The red blood cells contain haemoglobin. This is an iron-containing protein which transports oxygen to the organs. Without enough blood the body cannot function.

Blood can be lost for a variety of reasons; either internally or externally. With internal blood loss, the blood is lost from the circulation and commonly into the abdomen or thorax. With external blood loss, blood is lost from arteries or veins and leaves the body. Either of these situations is serious and potentially rapidly fatal.

The circulating blood volume for a rabbit is roughly 55-65 ml/kg of bodyweight. Therefore, a 2 kg rabbit will have between 110-130ml of blood. A loss of over 20-25% will result in shock.

Your veterinarian will perform a blood test, called a manual Packed Cell Volume (PCV) to determine if your rabbit is anemic and by how much, and if a blood transfusion may be necessary.

Unlike humans and to some degree dogs, there is no blood bank for rabbits. The donor rabbit should ideally be a littermate or if that is not possible (as is often the case), their bonded companion. If this is also not possible then an appeal may be made for a donor rabbit to come forward, although this will need to happen quickly. Donors must be fully vaccinated, healthy, should not be on any medication and should weigh at least 1kg. Ideally, they should also undergo a full biochemistry blood profile and blood count, as well as an E. cuniculi screen, but as time is of the essence the latter is unlikely to occur.

Up to 1% of bodyweight in blood can be collected, so a 2kg rabbit can give 20ml of blood safely. The jugular vein in the neck is often used for collection, this is the most suitable vein for collecting large volumes of blood before the blood clots. The rabbit is likely to need a light sedation to ensure they do not move during the collection.

The collection process is not without risk to the donor as any procedure carries some element of risk, but the small risks outweigh the benefit of potentially saving another rabbit’s life.

The rabbit receiving the blood transfusion may have an allergic reaction to the blood which can be serious and potentially fatal, although is not overly common. To help prevent this, the transfusion will be started very slowly and gradually sped up if there is no anaphylactic reaction.

The blood is given into one of the recipient rabbit’s veins and the volume given is based on what is safe to give cats and dogs (10-20ml/kg). The blood is given via a drip line which is attached to the syringe with the blood in it. This is then attached to a syringe pump. This ensures the correct amount is given over a set amount of time, to minimise reactions. The process can take several hours.

Ideally the rabbit will only require one transfusion in order to replace the blood lost while the bleeding is controlled, and the underlying cause is treated. Like people, rabbits have different blood groups and ideally blood donors and recipients should be from the same group, which will help minimize any reaction. In an emergency situation this is often not possible and giving a one off, unmatched donation is unlikely to cause any problems. If a second or subsequent transfusion is needed, the blood will have to be crossed and matched, otherwise a reaction is far more likely to occur.

The rabbit should start to stabilize within a matter of hours, but if the bleeding continues the improvement will be short-lived, so it is important that the cause is identified, and a treatment plan devised. If the rabbit requires surgery to stop the bleeding, then a blood transfusion prior to surgery will improve their chances of surviving surgery.