Cobalt in Horses: Risks, Toxicity, and Why It Should Not Be Used

By Dr Duncan Houston

If you hear cobalt being used as a performance enhancer, it should immediately raise concern.

Cobalt has been promoted in some performance settings as a way to improve stamina or oxygen delivery. In reality, there is no reliable evidence that it improves performance in horses, and there is clear evidence that it can cause serious harm.

This is not a grey area. It is a risk with no proven benefit.

Quick Answer

Cobalt is a trace mineral required in very small amounts for vitamin B12 production, but high-dose supplementation or injections are unsafe. There is no proven performance benefit, and excessive cobalt can cause cardiovascular problems, including arrhythmias and potentially fatal complications. It is banned in many competitive settings.

What Cobalt Actually Is

Cobalt is naturally present in a horse’s diet in very small amounts.

Its role:

• supports vitamin B12 synthesis

• contributes to normal metabolic function

Under normal feeding conditions:

• horses receive adequate cobalt from forage and feed

• additional supplementation is not required

This is where confusion begins.
A necessary trace mineral becomes dangerous when used in excess.

Why Cobalt Became a Performance Trend

Cobalt has been used with the idea that it might:

• increase red blood cell production

• improve oxygen delivery

• enhance stamina

This concept is loosely based on how other substances affect erythropoiesis.

However, in horses:

• this effect has not been reliably demonstrated

• dosing is unpredictable

• safety has not been established

In practice, the perceived benefits are not supported by evidence.

What Actually Happens at High Doses

Research and clinical observations show that high levels of cobalt can affect the cardiovascular system.

Reported effects include:

• increased heart rate

• elevated blood pressure

• anxiety or agitation

• cardiac arrhythmias

These are not mild side effects.
They indicate stress on critical systems.

How Serious Is This?

Low Exposure

• normal dietary intake

• no supplementation

What this means: safe and necessary for normal function

Moderate Concern

• unnecessary supplementation

• unclear dosing

What this means: no proven benefit, potential risk

High Risk

• injectable or high-dose cobalt use

• repeated exposure

What this means: significant risk of toxicity

Critical

• signs of cardiovascular instability

• arrhythmias or collapse

What this means: potentially life-threatening toxicity

Why Cobalt Is Dangerous

Cardiovascular Risk

The most immediate concern is the heart.

Cobalt can:

• disrupt normal heart rhythm

• increase cardiovascular strain

• lead to potentially fatal complications

Systemic Effects

At higher or repeated doses, cobalt may affect:

• nervous system function

• endocrine balance

• overall metabolic stability

These effects are not always predictable.

No Defined Safe Dose

One of the biggest issues is uncertainty.

• there is no established safe therapeutic dose for performance use

• effects vary between horses

• accumulation may occur

This makes dosing inherently risky.

Regulatory and Ethical Considerations

Cobalt is prohibited or tightly regulated in many equine sports.

Consequences of use may include:

• disqualification

• fines

• suspension

Beyond regulation, there is a clear welfare issue.

Using a substance with known risks and no proven benefit does not align with responsible horse management.

What To Do If You Are Concerned About Exposure

If you suspect cobalt use or exposure:

• stop any supplementation immediately

• monitor for changes in behaviour or performance

• involve a veterinarian for assessment

• consider cardiac evaluation if signs are present

Early recognition is important, especially if cardiovascular signs develop.

When Is This an Emergency?

Seek immediate veterinary care if you observe:

• irregular or rapid heart rate

• weakness or collapse

• laboured breathing

• severe agitation

These may indicate serious systemic or cardiac involvement.

Common Mistakes

• assuming more supplementation improves performance

• using substances without evidence of benefit

• ignoring early signs of toxicity

• relying on anecdotal practices rather than clinical evidence

In practice, these situations often arise from misinformation rather than intent.

Long-Term Approach to Performance

Performance is best supported through:

• appropriate conditioning

• balanced nutrition

• workload management

• recovery strategies

There are no safe shortcuts that replace these fundamentals.

Frequently Asked Questions

Is cobalt necessary in a horse’s diet?
Yes, but only in very small amounts naturally provided in feed.

Can cobalt improve performance?
There is no reliable evidence that it does.

Is cobalt toxic to horses?
At high doses, yes. It can affect the heart and other systems.

Why is cobalt banned in competition?
Due to welfare concerns and lack of proven benefit.

Should I use cobalt supplements?
No. They are unnecessary and potentially dangerous.

Final Thoughts

Cobalt is a clear example of a substance that sounds beneficial in theory but does not hold up in practice.

The key points are simple:

• horses already receive what they need through normal feeding

• additional cobalt offers no proven advantage

• excessive use carries real risk

When it comes to performance and health, the safest and most effective approach is still based on sound management, not unproven shortcuts.

If you are unsure about supplements, performance products, or whether something is safe for your horse, ASK A VET™ can help you review options and make informed, evidence-based decisions.