🩺 Deadly Nightshade Poisoning in Horses: A Vet’s 2025 Guide | Dr Duncan Houston BVSc

Meta description: Toxic belladonna ingestion causes serious anticholinergic symptoms in horses. Learn to identify, respond, treat, and prevent in 2025.

1. 🧬 What Is Deadly Nightshade?

Atropa belladonna, commonly known as dead­ly nightshade or belladonna, is a perennial herb in the Solanaceae family. It contains potent tropane alkaloids (atropine, scopolamine, hyoscyamine) that block parasympathetic nervous system functions and can be fatal to horses even in small quantities :contentReference[oaicite:3]{index=3}.

2. 🌿 Why Horses Are At Risk

Horses generally avoid nightshade due to its bitterness. Poisoning occurs when leaves, stems or berries contaminate hay or during grazing of poor-quality pasture :contentReference[oaicite:4]{index=4}. Dried plant parts remain toxic and may accumulate, causing chronic exposure :contentReference[oaicite:5]{index=5}.

3. ⚠️ Signs & Clinical Effects

• Anticholinergic signs: Dilated pupils, light sensitivity, dry mouth, decreased gut sounds :contentReference[oaicite:6]{index=6}.
• GI and nervous system effects: Colic, diarrhea/constipation, urinary retention, tremors, incoordination, seizures, collapse :contentReference[oaicite:7]{index=7}.
• Cardiovascular: Tachycardia, irregular heart rhythms :contentReference[oaicite:8]{index=8}.

4. 🩺 Diagnosing the Poisoning

Diagnosis relies on:

• History of exposure and clinical presentation.
• Inspecting feed/hay for nightshade fragments.
• Lab work, including CBC and chemistry to assess hydration, electrolytes, and organ function.
• No specific test—targeted testing may confirm plant ingestion :contentReference[oaicite:9]{index=9}.

5. 🏥 Emergency Treatment & Support

• Remove contaminated feed immediately.
• IV fluids: Manage dehydration and support renal function.
• Activated charcoal: Given early to reduce toxin absorption :contentReference[oaicite:10]{index=10}.
• Antidote: Neostigmine or physostigmine to counter atropine effects :contentReference[oaicite:11]{index=11}.
• Symptomatic care: Anti-arrhythmics, gastric protectants, anti-convulsants if needed.
• Ventilation and cooling: For hyperthermia and respiratory strain.

Prognosis varies: mild cases recover well with prompt treatment; severe intoxication carries a guarded prognosis.

6. 🛡️ Prevention & Management

• Pasture maintenance: Remove any nightshade plants (all parts) promptly :contentReference[oaicite:12]{index=12}.
• Hay sourcing: Only use reputable suppliers; inspect stored hay regularly.
• Weed control: Avoid overgrazed pastures; rotate grazing areas.
• Education: Train staff to identify nightshade in varying stages.

7. 💬 Ask A Vet Support Services

Through Ask A Vet you can access:

• 📸 Remote assessment of hay/pasture photos for contamination risk.
• 📋 Tailored emergency response protocols and treatment checklists.
• 📆 Care-plan reminders for follow-up exams, blood tests, and pasture monitoring.
• 🎓 Webinars: “Identifying Toxic Weeds,” “Hay Screening Protocols,” “Anticholinergic Emergencies.”

8. ❓ FAQs

Can a small leaf kill a horse?

Yes—even a few dried leaves can accumulate enough toxin to cause serious illness :contentReference[oaicite:13]{index=13}.

Will the horse be ill long-term?

Recovery is possible, but monitoring kidney, gut, and neurological function is important—some may have lasting GI or nervous effects.

Is physostigmine available? What are risks?

It’s prescription-only and should be administered under vet supervision due to risk of bradycardia and GI spasm.

Can humans be poisoned via milk or meat?

Toxic alkaloids may pass into milk. Consumption of meat or milk from exposed animals is not recommended.

9. ✅ Final Takeaway

Deadly nightshade poisoning is rare but potentially fatal. Early detection and aggressive treatment—IV fluids, charcoal, antidotes—can save lives. Prevent by removing weeds and inspecting feed. Ask A Vet provides critical remote tools and expert support to help ensure your horse's safety in 2025 and beyond.