🧬 Vet Warning 2025: Plant Toxins and Liver Disease in Horses—What to Watch For 🌿🐎

Liver disease isn’t the most common condition in horses—but when it does appear, it’s often linked to toxic plant exposure. Because the liver is involved in so many vital processes, damage to this organ can cause subtle signs at first and lead to serious complications later. In this 2025 equine toxicology guide, Dr Duncan Houston explains how to recognize liver disease symptoms, identify common plant toxins, and take steps to protect your horse from exposure. 🧠

🧪 Signs of Liver Disease in Horses

The early signs of liver dysfunction are often nonspecific, making diagnosis tricky. Common symptoms include:

• 😴 Lethargy or depression
• 🥱 Excessive yawning
• 🐴 Decreased appetite
• 💢 Behavioral changes or confusion
• 💛 Yellow discoloration of gums or eyes (jaundice)
• 🤢 Colic-like discomfort or bloating

As liver damage progresses, your vet may notice elevated liver enzymes on bloodwork. In severe cases, neurologic signs or photosensitivity may occur. ☀️

🌿 Common Plant and Feed Toxins That Damage the Liver

1. 🌱 Pyrrolizidine Alkaloids (PAs)

PAs are a group of toxic compounds found in many common weeds. Horses typically ingest them when:

• 🌾 Hay is baled with toxic plants
• 🌿 Grazing is poor and forage options are limited

Plants that contain PAs include:

• 🟢 Senecio species (e.g., Tansy ragwort, groundsel)
• 🌼 Crotalaria (Rattlebox)
• 🌾 Heliotropium (Common heliotrope)

PA toxicity is cumulative—even small amounts over time can build up and cause liver damage. Horses typically avoid these plants unless there is no other forage available. 🚫

2. 🌿 Cocklebur (Xanthium spp.)

This plant is especially dangerous in its early two-leaf seedling stage. The toxin is concentrated in the cotyledons (first leaves), and because cocklebur seedlings emerge before most other spring forage, horses may consume them out of hunger or curiosity.

Dr Duncan Houston recommends checking pastures carefully in early spring and supplying quality hay to prevent horses from grazing toxic sprouts. 🌱

3. 🦠 Aflatoxins in Moldy Grain

Aflatoxins are produced by fungi (Aspergillus spp.) that grow on stressed or improperly stored grains. These toxins can:

• 💥 Damage the liver and other organs
• 🧠 Lead to neurologic symptoms
• 💔 Cause poor growth or weight loss

Contamination can occur in the field during drought or in storage with moisture and heat. Even grain that looks clean may still contain invisible aflatoxins. 📉

4. 🌊 Blue-Green Algae (Cyanobacteria)

Algae blooms in stagnant water or ponds can produce liver-damaging toxins. These algae often appear as green or bluish film on the surface and thrive in hot, nutrient-rich water. Signs of exposure include:

• 🫁 Respiratory distress
• 🤒 Sudden weakness
• ⚰️ Collapse or death in severe cases

If you see signs of an algal bloom, immediately restrict pond access and provide fresh, clean water. 💧

📋 Prevention Tips: How to Protect Your Horse

1. ✅ Know Your Weeds

• 🧠 Learn to identify common liver-toxic plants in your region
• 🚫 Remove toxic plants from pastures and fence lines
• 🌿 Avoid overgrazing, which encourages weed growth

2. 🧪 Test Feed When in Doubt

• 🌾 Have suspicious hay or grain tested for toxins or mold
• 📦 Only buy hay from trusted, reputable sources

3. 🧼 Proper Feed and Water Storage

• 🏠 Store hay and grain in a dry, cool location
• 🛢️ Never use old fertilizer or chemical tanks for hauling water
• 🚿 Clean water troughs and tanks regularly

4. 🧬 Monitor Horses Closely

• 📈 Regular bloodwork for liver values in at-risk horses
• 👀 Watch for appetite changes, mood shifts, or strange behaviors

📲 Ask A Vet: Toxicity and Liver Health Support

Worried your horse may have eaten a toxic plant—or showing strange signs? The Ask A Vet app gives you fast access to veterinarians like Dr Duncan Houston who can assess symptoms, photos, and pasture conditions. 📱🐎

• 📸 Share pasture or feed images
• 🧪 Upload bloodwork or toxin test results
• 💬 Get personalized treatment and prevention advice

Download the Ask A Vet app today and protect your horse’s liver and long-term wellness with real-time guidance. 🧬

🏁 Final Thoughts: Prevention Is the Best Treatment

Liver disease may be rare in horses—but it’s often preventable. By managing pastures, storing feed correctly, and avoiding known toxic plants and molds, you can dramatically reduce the risk of liver damage. ✅

If your horse shows any signs of illness, especially behavioral or digestive changes, don’t wait. Catching liver disease early can make all the difference. 🧠

🐾 For expert insight and immediate help, visit AskAVet.com or download the Ask A Vet app to speak with Dr Duncan Houston and start protecting your horse from hidden plant dangers today. 🌿🐎💙