Anaemia
Horses become anaemic when they have a reduction in the number of red blood cells (RBC's) or have inadequate haemoglobin within them, however, anaemia is probably one of the most commonly misdiagnosed disorders in horses and is not usually a disease in itself, but rather the sign of an underlying problem.
The purpose of the RBC's is to transport oxygen to the tissues from the lungs and to return carbon dioxide for elimination from the body and if there isn't enough oxygen the animal can't perform. Tissue functions, like muscle contraction, can't operate normally and the heart is placed under pressure to try and compensate.
Anaemia is most commonly seen as a result of blood loss, which can be internal or external, the destruction of red blood cells, immune mediated haemolytic aneamia (e.g. swamp fever), reduction in the production of red blood cells or secondary to any chronic disease. It may be caused by nutritional problems, for example iron deficiency or deficiency of vitamin B12, however, these are rare and most balanced diets contain more than enough iron to allow the horse to maintain normal numbers of red blood cells and the use of supplements containing high quantities of iron can actually be detrimental.
Signs
The condition will usually cause pale membranes and, if blood is analysed, the levels for RBC's and/or haemoglobin will be reduced. Animals will occasionally show fatigue and weakness.
Treatment
Mild cases of anemia should be monitored and vitamin B supplementation may be carried out. As most cases of anemia are the sign of an underlying problem the animal must be very carefully examined and many tests carried out to diagnose this condition as once the root cause has been diagnosed and treated, the body usually treats the anaemia itself.
In cases of bleeding the area of blood loss must be quickly identified and stopped.
Some animals must be hospitialised and given fluids or even blood transfusions to keep them stable until a diagnosis can be made and, if possible, treated.