New Blood

A transfusion can be life-saving for a sick or injured horse — with little risk to the donor. Victoria South MRCVS explains how the process works.

A HORSE may require a blood transfusion when his life is at risk due to the volume of blood he has lost. This could be due to external haemorrhage (bleeding from blood vessels into the outside world), internal haemorrhage (bleeding into a body cavity), or because the horse’s own immune system has destroyed its red cells due to autoimmune disease.

A vet makes a decision on the need for a transfusion based on the horse’s vital signs. Certain parameters will be checked for evidence of haemorrhagic shock, including his heart rhythm and rate, respiratory rate and effort, and pulse strength.

The temperature of the horse’s extremities may drop, leaving his ears and lower legs feeling cooler than normal. His mucous membranes (the insides of his mouth and nose and under his eyelids), typically pale pink, may turn white.

External haemorrhage may be caused by lacerations to superficial blood vessels by sharp objects (wire, glass, metal spikes or shards of wood) or, rarely, gunshots. Loss of blood from surgery is another hazard.

As a general rule, wounds with infrequent drips of blood are unlikely to result in lifethreatening haemorrhagic shock, whereas those with a constant stream could lead to loss of life. The amount of blood loss will be greater and the bleeding is less likely to stop (clot) on its own.

It is important to remember that lacerations and puncture wounds can also damage underlying tissue and joints.

It is always best to consult your vet as a matter of urgency when a wound is detected with any significant bleeding or near a joint.

Significant internal haemorrhage can result from blunt trauma to the chest or abdomen. This trauma tends to occur during high-speed collisions with solid objects such as cross-country fences, paddock fencing or vehicles, or when the horse hits the ground with force (perhaps in a rotational fall, or if he rears up and falls backwards or sideways).