Up to 1940 bloodletting was still used but since then no longer considered acceptable. Today however, renewed interest in this treatment is on the rise. By draining blood an attempt is made to lower the blood pressure. The idea behind this is twofold. Firstly, a lower blood pressure slightly reduces the flow of MMPs. Secondly, the lowering of blood pressure helps to prevent blood serum leaking from the capillaries which slightly decreases the risk of oedema formation between the hoof wall and the coffin bone. The pulsations in the hoof reduce which eases the pain. However, soon after treatment the blood pressure will recover, although usually not completely up to previous levels. With regard to oedema formation bloodletting remains just a symptomatic measure. Also the decreased supply of MMPs is a short-lived effect.
A second aim is to reduce the viscosity of the blood. After bloodletting the body tries to restore the blood volume as quickly as possible. To make this happen, fluid is drawn from tissues and added to the blood. The idea behind it is blood that flows more easily will provide better circulation. This brings the bloodletting treatment in line with the circulation and trauma theories. Again, the viscosity of the blood will quickly return to its previous level.
Lastly, some veterinarians use this treatment in an attempt to remove toxins from the blood or to reduce iron in blood for horses with iron overload.
Disadvantages and complications
The rapid changes in blood volume and fluid balance have adverse effects on mineral concentrations in the body. Besides, bloodletting potentially has the following complications:
- Vascular infections
- Nerve or tissue damage by keeping the tourniquet on for too long