Supplementing a Horse for Anemia

By Dr. Lydia Gray on August 27, 2008 at 1:46 pm
Diseases and Conditions

I recently had my horse's blood tested due to concern of anemia. He is a 4 yr old WB/TB, gelded just a few months ago. During work he has plenty of energy and is very fit, but he is the calmest horse I have ever known, sometimes bordering on lethargy which prompted my concern. He usually uses his turnout time as nap time. His red blood cell levels came back within the range but on the low side: 7.7 on a 6.5-11.9 range. The vet I talked to said that was OK but low for a performance horse (eventing) and recommended I start my horse on iron supplements. I hesitate to do this because of my concern of the adverse effects of too much iron. I read that vitamin B supplements are more effective. Is this true, or would iron supplements be best for my horse? EM, Illinois

Dear EM,

I’m glad you brought up this topic because it’s a question we get asked a lot here—is iron the best thing to give a horse with anemia? To answer that, we should really begin with—what is anemia? The Merck Veterinary Manual defines anemia as an absolute decrease in the circulating red blood cell (RBC) mass as measured by RBC count, hemoglobin (Hb) concentration, and packed cell volume (PCV) also known as hematocrit. The number you gave (7.7) is your horse’s RBC count. Did your veterinarian also measure his Hb concentration and PCV? What about a serum chemistry panel or blood smear?

The reason I ask is that the best way to treat anemia is to find out the cause, treat that, then supply the building blocks of healthy red blood cells while your horse is recovering. Otherwise, you’re just treating the symptom and not the problem. There are three main categories of anemia:

• Blood loss

• RBC destruction

• Inadequate RBC production

Blood loss can be acute, like hemorrhage from an external injury, or it can be chronic, like bleeding from a gastric ulcer. Anemia from red blood cell destruction is called hemolytic anemia, and can be caused by toxins, immune diseases or infectious agents. The most common cause of inadequate RBC production is called “anemia of chronic disease” and usually improves on its own as soon as the underlying condition is resolved.

Your veterinarian is correct in saying that your horse’s RBC count, while within the normal range, is low for a part-thoroughbred event horse because well-conditioned or “hot-blooded” horses like thoroughbreds generally have higher blood values than poor-conditioned or “cold-blooded” horses like drafts. So while the two of you figure out why he may be on the low side of normal, here are some helpful suggestions.

First of all, none of the typical ingredients of a hematinic, or blood-builder, have been shown to actually stimulate red blood cell production. All that these ingredients can do is be available when red blood cells are being produced. Here are some ingredients common in blood-builders because they are known to be involved in the production of RBCs:

• Iron

• Copper

• Zinc

• Cobalt

• Vitamin B12 (cyanocobalamin)

• Folic Acid (another B vitamin)

Iron is the most commonly seen ingredient in products for anemia because it is a critical component of hemoglobin, the compound within RBCs that actually picks up oxygen from the lungs and deposits it in tissues. However, unless a horse has lost a significant amount of blood or does not have access to soil, iron deficiency is not a common cause of anemia. This is because the iron from RBCs is recycled as they reach the end of their normal life span and are taken out of circulation by the spleen. While feeding high amounts of iron to horses for a short-time was recently shown not to cause any ill effects, excess iron in the diet may prevent the absorption of other minerals such as zinc and copper and create deficiencies.

PS A study performed in 2001 by the Equine Research Centre in Guelph, Ontario found that a product containing Echinacea not only caused an increase in the number circulating white blood cells (lymphocytes), but also an increase in the size and number of circulating red blood cells, as well as an increase in the level of hemoglobin.