Our Vet & Nutritionist Guide to Equine Liver Health, Management & Supplement Support

Equine liver disease (hepatitis) affects one of the most important organs in the horse’s body — the liver. As the largest internal organ, it plays a vital role in metabolism, detoxification, vitamin storage, and overall health.

The good news is that the liver has a remarkable ability to compensate and regenerate. However, the challenge is that clinical signs often only appear once significant damage has already occurred.

For this reason, proactive management, including diet, monitoring, and equine liver support supplements,  can play an important role in long-term care.

Understanding the Equine Liver

The horse’s liver typically accounts for approximately 1–1.5% of bodyweight, but its metabolic importance is far greater than its size suggests.

It is responsible for:

• Metabolising carbohydrates, fats, and proteins
• Detoxifying harmful compounds
• Processing medications
• Storing vitamins and minerals
• Producing bile for digestion

Because of its high functional reserve, up to 70% of liver function can be compromised before obvious symptoms appear.

This is why early nutritional support and monitoring are essential in at-risk horses.

Clinical Signs of Equine Liver Disease

Liver dysfunction in horses often develops gradually and can present with vague or non-specific symptoms. For this reason, early veterinary assessment is essential if you notice any changes in your horse’s behaviour, appetite, or condition.

As veterinary director Dr Andy Richardson explains, liver disease is often only identified once significant compromise has already occurred, making early recognition of subtle signs particularly important.

If you notice any of the following, veterinary advice should always be sought promptly:

• Jaundice (yellowing of gums, eyes, or skin)
• Lethargy or reduced energy
• Weight loss or loss of condition
• Reduced appetite or feed refusal
• Photosensitivity (sunburn-like reactions)
• Neurological changes (including circling, disorientation, or head pressing)
• Digestive disturbances (such as diarrhoea, constipation, or colic-like signs)
• Abnormal bleeding or delayed clotting
• Anaemia, particularly in chronic or advanced cases

Because these clinical signs can overlap with many other equine conditions, definitive diagnosis should always be made in consultation with a veterinary professional, supported by blood testing and further investigation where required.

Causes of Liver Disease in Horses

Understanding the underlying cause is key to effective management and long-term recovery.

Ragwort poisoning in horses

One of the most well-known causes of liver damage is ragwort poisoning in horses. The plant contains pyrrolizidine alkaloids, which destroy liver cells and lead to irreversible fibrosis.

Fresh ragwort is typically avoided by horses due to its bitter taste, but dried plants in hay or contaminated forage become far more dangerous.

Effective pasture management and removal of toxic plants is essential for prevention. For detailed identification, risks, and pasture management guidance, refer to the British Horse Society (BHS) guidance on ragwort control and pasture safety.

Mycotoxins in forage and feed

Poorly stored or damp feed can contain invisible fungal toxins known as mycotoxins.

Even when mould is not visible, contamination may still be present.

In some cases, nutritional strategies such as mycotoxin binders for horses may be considered as part of a veterinary-led management plan.

Parasites and liver fluke exposure

Although less common than in cattle or sheep, horses can occasionally be exposed to liver fluke through contaminated pasture.

Infection and viral causes

In rare cases, bacterial or viral infections may contribute to liver inflammation or dysfunction. Research is ongoing into emerging viral associations with equine hepatitis.

Diagnosing Liver Disease in Horses

Veterinary diagnosis typically involves:

Physical examination

Including assessment for jaundice, body condition, and general health status.

Blood testing

Key liver markers include:

• GGT (Gamma-glutamyl transferase)
• GLDH (Glutamate dehydrogenase)
• AST (Aspartate aminotransferase)

Additional indicators:

• Bile acids (liver function efficiency)
• Ammonia levels (detoxification capacity)

Advanced diagnostics

Where required:

• Ultrasound imaging
• Liver biopsy for definitive diagnosis

For ongoing cases, regular equine liver blood testing is often used to monitor progress.

Treatment & Veterinary Management

Treatment depends heavily on cause and severity.

Veterinary approaches may include:

• Antibiotics (for infection-related cases)
• Anthelmintics (for parasitic involvement)
• Anti-inflammatories or steroids (to reduce inflammation)

While fibrosis is irreversible, the liver can regenerate, meaning long-term outcomes can still be positive with correct management.

Nutrition for Horses with Liver Disease

Head Nutritionist Kate Hore explains that nutrition plays a central role in supporting recovery and long-term liver health.

A suitable diet should focus on:

• High forage intake
• Low starch and low sugar feed
  
• Minimal metabolic stress

This approach is often paired with equine liver support nutrition plans designed in collaboration with your vet or nutritionist.

Protein & Energy Considerations

Historically, low-protein diets were recommended. However, veterinary nutrition research by Durham (2013) in Equine Applied & Clinical Nutrition suggests that liver-compromised horses may actually benefit from adequate (not excessive) protein intake due to reduced absorption efficiency.

The key is balance — not restriction.

Always evaluate protein based on total daily intake, not just feed label percentages.

Understanding Protein Analysis

When reviewing protein levels in horse feeds, it is essential to consider the feeding rate alongside the nutritional analysis, as protein percentages alone can be misleading.

This is particularly important when evaluating highly concentrated products such as supplements, where protein levels may appear high on paper due to formulation, but contribute very little in real daily intake.

Example Daily Protein Contribution (500kg Horse)

The following example demonstrates how different feed sources contribute to total daily protein intake.

What this means in practice

Although concentrated products such as equine liver support supplements may show higher protein percentages on analysis, their actual contribution to total daily protein intake is very small due to the low feeding rate.

This is why nutritional evaluation should always focus on the whole diet approach, rather than individual ingredient percentages in isolation.

Balanced Diet & Micronutrients

Even forage-based diets often lack key micronutrients.

A well-formulated equine vitamin and mineral balancer helps ensure adequate intake of:

• Zinc (important for liver function)
• Selenium
• Vitamin E
• B vitamins

Soil deficiencies across the UK make this particularly important.

Iron Management

Iron is not usually required in supplementation and may be excessive in some diets.

For horses with liver compromise, choosing iron-free horse supplements is often recommended unless specifically advised otherwise by a vet.

Targeted Liver Support Supplements

In addition to a balanced diet, targeted supplementation can support liver function and recovery.

Key ingredients include:

• Milk thistle (Silybum marianum)
• Silymarin / silybin compounds
• Antioxidants
• Fat-soluble vitamins (A, D, E, K)
• Zinc

Milk thistle for horses (Silybum marianum) is one of the most researched botanical ingredients used in equine liver support formulations, known for its hepatoprotective and antioxidant properties.

Long-term Management

Supporting a horse with liver disease is typically a long-term commitment. In practice, management is usually centred around:

• Consistent diet and targeted supplementation
• Regular blood monitoring
  
• Ongoing veterinary collaboration

Conclusion

Equine liver disease can be challenging, but with early veterinary intervention, appropriate nutrition, and ongoing management, many horses can continue to thrive. A balanced diet, careful forage management, regular monitoring, and targeted liver support can all play an important role in supporting long-term liver health and recovery.

References