Deadly Nightshade Poisoning in Horses: What to Do After Suspected Exposure

By Dr Duncan Houston

Finding a poisonous plant in a paddock is worrying. Finding chewed stems or suspicious material in your horse’s feed makes prompt action more important than trying to calculate a safe amount yourself.

“Nightshade” is used for several different plants. Correct identification matters because their toxins and effects are not identical.

Quick Answer

If your horse may have eaten deadly nightshade, remove access and call your equine vet immediately, even if the horse seems normal. Deadly nightshade, Atropa belladonna, contains toxins that interfere with normal nerve signalling and can affect the gut, heart and nervous system. Do not give home antidotes or force anything into the mouth.

What makes deadly nightshade dangerous?

Atropine, hyoscyamine and scopolamine interfere with muscarinic acetylcholine receptors. In practical terms, poisoning can reduce secretions and gut movement while disturbing heart rate and behaviour. The University of Zurich’s veterinary toxicology reference confirms that dried material remains poisonous and toxin content varies.

That variability makes leaf counts unreliable. The amount eaten, plant part, identification and the horse’s condition all affect assessment. Avoid claims that one leaf will inevitably kill a horse, but do not interpret an apparently small exposure as safe.

Deadly nightshade is different from black nightshade and bittersweet nightshade. A useful identification sample includes leaves, stems and any flowers or fruit, not just one berry. Wear gloves, keep children and other animals away, and do not taste any part of the plant.

What signs should you watch for?

Possible signs include unusually large pupils, dry mouth, rapid heart rate, agitation, reduced manure passage, abdominal pain, weakness and poor coordination. Severe poisoning can cause collapse or respiratory failure. A horse with neurological signs can injure people unintentionally, so observation must remain safe.

Could another problem cause these signs?

Yes. Other toxic plants, contaminated feed, medication effects, intestinal disease and neurological disorders can overlap. Identification helps the vet choose appropriate treatment, but waiting for a perfect photograph or laboratory result can waste valuable time.

The Swedish National Veterinary Institute also provides a belladonna toxic-plant reference. Use veterinary or botanical expertise rather than relying on an image-identification app alone.

When is this an emergency?

Suspected ingestion warrants an immediate phone call; developing signs warrant emergency care. Collapse, inability to stand, severe colic, uncontrolled agitation, seizures or laboured breathing require urgent veterinary intervention. Do not transport an unstable horse before discussing a safe plan.

What should you do right now?

1. Move unaffected horses away from the source if safe. Remove suspect feed without throwing it away.
2. Phone your vet with the time of possible exposure, horse’s approximate weight, symptoms and any medication already given.
3. Photograph the plant and preserve a labelled sample away from feed, children and animals.
4. Keep the affected horse quiet in a safe area. Do not chase, exercise or tightly restrain an agitated horse.
5. Follow the vet’s instructions about water, feed, transport and monitoring while help is arranged.

Horses cannot be made to vomit safely. Activated charcoal, stomach tubing, intravenous fluids and specific medication require clinical judgement and appropriate administration. An uncoordinated horse can inhale a drench. There is no safe owner-administered universal antidote.

Veterinary care may include decontamination when appropriate, heart and temperature monitoring, fluids and treatment of gut or neurological complications. Outcome depends on exposure and clinical severity; early help improves the chance of effective intervention without guaranteeing recovery.

Common mistakes

• Waiting for symptoms after a credible ingestion.
• Assuming dried weeds in hay are harmless.
• Confusing all plants called nightshade.
• Giving oil, salt, herbal remedies or charcoal without instructions.

Preventing exposure

Inspect paddocks, boundary vegetation and hay. Provide adequate safe forage so horses are less tempted to browse unfamiliar plants. Manage weeds before they contaminate feed, and keep horses away from cut or wilted vegetation. Follow local professional advice for removal and herbicide withholding periods.

Frequently asked questions

Can I wait if my horse looks normal?

No. Call promptly after suspected ingestion; the absence of signs does not establish safety.

Is dried deadly nightshade safe?

No. Drying does not reliably remove its toxicity.

How much is poisonous?

No household leaf-count rule can safely predict risk. Give exposure details to your vet.

Should I bring a plant sample?

Yes, if it can be collected safely without delaying help. Label and contain it securely.

Remove access, preserve evidence and call early. Those practical steps are more useful than trying a home treatment.

For help understanding your horse’s care and preparing questions for your veterinarian, visit ASK A VET™. Urgent signs need an equine veterinarian in person.