Blood Builders in Performance Horses by a Vet – 2025 Guide to Iron, EPO, and Red Blood Cell Myths 🩸🐎
In this article
Blood Builders in Performance Horses by a Vet – 2025 Guide to Iron, EPO, and Red Blood Cell Myths 🩸🐎
By Dr Duncan Houston, BVSc
Introduction
The quest for peak performance has led many horse owners and trainers to turn to supplements known as “blood builders.” These products claim to enhance athletic performance by increasing the number of red blood cells—improving oxygen transport, stamina, and speed. In 2025, despite their widespread use, there is limited scientific support for their efficacy in healthy horses, and some of these products may pose serious health risks.
What Are Blood Builders? 🔬
Also known as hematinics, blood builder supplements aim to increase red blood cell (RBC) count and hemoglobin levels in horses. Common ingredients include:
- Iron (ferrous sulfate or gluconate)
- Copper
- Vitamin B12
- Folic acid
- Thiamine & Riboflavin
- Recombinant human erythropoietin (rhEPO) – a banned, synthetic hormone
The Theory Behind Blood Builders 🧠
- Red blood cells carry oxygen to muscles via hemoglobin
- Increasing RBC count may improve aerobic capacity and endurance
- More oxygen could mean better stamina and faster recovery
Why Iron Doesn’t Work for Most Horses 🧲
- Horses rarely suffer from iron deficiency unless there’s chronic bleeding or malnutrition
- Iron is tightly regulated by the horse’s body
- Excess iron is not stored safely and may cause oxidative damage or interfere with copper absorption
- Studies have shown no benefit of supplemental iron in non-anemic horses
Red Blood Cell Testing Myths 🧪
- Resting blood samples are misleading in horses
- About 30% of a horse’s red blood cells are stored in the spleen
- During exercise or stress, the spleen contracts, releasing stored RBCs into circulation
- Therefore, low RBC counts at rest do not mean deficiency
The Dangers of Erythropoietin (EPO) in Horses ⚠️
What Is EPO?
- A hormone that stimulates red blood cell production
- Used in human medicine for anemia or kidney failure
- Illegal and banned in racing and equestrian sports
Risks of Using EPO in Horses
- Increased blood viscosity (thicker blood) → higher risk of clotting and stroke
- Potential for autoimmune reactions against the hormone or blood cells
- Especially dangerous when combined with furosemide (Lasix), a common anti-bleeding medication
Performance Implications ⚡
- Most performance horses do not benefit from additional RBCs
- There is no consistent link between blood builders and improved performance
- Over-supplementing is more likely to cause harm than enhance results
When Blood Builders Might Be Needed 🧬
- Documented anemia from blood loss or chronic disease
- Recovery from surgery, illness, or parasites
- In these cases, veterinary-prescribed hematinics are appropriate short-term
Case Example: Barrel Racer with Chronic Fatigue
- 6-year-old mare became sluggish and underperformed at events
- Owner started her on over-the-counter iron supplement
- No improvement after 4 weeks
- Veterinary exam revealed gastric ulcers and electrolyte imbalance
- After treating ulcers and correcting diet, performance returned
- Iron supplement was discontinued
FAQs About Blood Builders in Horses
Q: Is iron ever helpful in horses?
A: Only when a horse is truly iron-deficient, which is rare. Over-supplementation can be harmful.
Q: Can blood builders improve race times?
A: Not in healthy horses. The spleen naturally boosts red blood cells during performance.
Q: Are there legal EPO alternatives?
A: No. Any hormone that manipulates red cell mass is considered performance-enhancing and is prohibited.
Conclusion
Blood builder supplements continue to attract attention in the performance horse world—but in 2025, science shows they are largely unnecessary and potentially dangerous. Iron is rarely deficient, erythropoietin is risky and unethical, and resting red cell counts are often misinterpreted. Focus instead on a balanced diet, parasite control, hydration, and fitness to keep your performance horse at its best.
Want help optimizing your horse’s health or evaluating a supplement? Visit AskAVet.com or download our app 📱 to connect with Dr Duncan Houston for performance nutrition advice. 🩺🐴
