Various hematinics or "blood-builders" have been administered to racing horses in an attempt to enhance their performance.
These hematinics come in the form of nutrients (iron, copper, B12, thiamin, riboflavin and folic acid) and injected compounds, including recombinant human erythropoietin (rHuEPO), a potent
drug that is used in human medicine to treat anemia of end-stage renal failure.
These products are reported to increase red cell production and hemoglobin in an effort to boost aerobic capacity in exercising
horses. But there is little evidence of their safety and efficacy. Iron, the major component of "nutrient-based" hematinics,
is well regulated by the body, efficiently used and rarely deficient in the healthy horse. And the few studies that have focused
on such nutrients have shown no benefit to supplementation.1
Products that do actually increase red cell production are unethical and potentially dangerous to the horse's health. In racehorses,
the use of rHuEPO may have serious health effects, especially if administered in concert with furosemide.
Normal equine physiology
Blood volume in the horse is about 8 percent of body weight. So a 500 kg horse has about 40 L of blood. Red blood cells (RBCs),
which are produced in the bone marrow, have a normal life cycle of approximately 140 days and are efficiently replaced, as
is their hemoglobin content. Aged RBCs are removed by the spleen, their iron content used to make new RBCs. The ongoing process
of RBC production is dependent on growth factors and an adequate supply of essential nutrients.
The main growth factor is erythropoietin, a hormone produced predominantly by the kidneys that stimulates the stem cells within
the bone marrow to manufacture needed RBCs. It's a process that can take as few as two days, but more commonly five to seven.
Nutrients essential to erythropoesis, especially for oxygen-carrying hemoglobin production, are iron, copper, B12, thiamin, riboflavin and folic acid.