Hemlock and Acorn Toxicity in our Livestock. As the summer grazing quality has been low we are starting to see livestock looking through hedgerows and other sources for their nutritional needs. Not all forage is good for our livestock and sadly we are seeing spikes in animals dying due to ingesting toxic plants:
HEMLOCK: Summer’s secret weapon
Hemlock (Conium maculatum) poses a serious and often fatal threat to cattle and sheep, especially during periods of dry weather when livestock may forage more aggressively and encounter exposed roots. This summer’s prolonged dry conditions have heightened the risk, with recent cases reported in the South West of England where multiple cattle succumbed to poisoning.
Identification and Toxicity
Hemlock is a tall, hollow-stemmed plant with purple blotches and umbrella-like clusters of white flowers. It resembles cow parsley but has a distinctive “mousy” odour when crushed
All parts of the plant are toxic, with the green fruit and stems being particularly dangerous. The toxic dose for livestock is approximately 15.5 mg/kg, and symptoms can appear within 1–2 hours of ingestion .
Recent Cases and Risk Factors
Veterinary reports from Tyndale Vets highlight the severity of recent outbreaks. In one case, eight cattle died after consuming hemlock roots exposed in a ditch. Despite having access to silage and water troughs, the cattle were drawn to the roots, which are particularly palatable during dry spells. Additionally we did a recent post about acorn poisoning, where forage is limited, please remain vigilant, as quick treatment of these animals is the only chance to save these cattle
As autumn arrives, oak trees begin shedding acorns — a seasonal hazard for livestock. While they may seem harmless, acorns contain toxic compounds that can cause serious illness or death in cattle, sheep, and horses.
ACORNS: What Makes Acorns Toxic?
Acorns and oak leaves contain phenols and tannins, especially gallotannin, which break down in the rumen into gallic acid and tannic acid. These substances:
- Cause ulceration in the mouth, oesophagus, and intestines
- Lead to kidney damage, which is the primary cause of death in affected animals
Green acorns are particularly dangerous, and toxicity increases when animals consume large quantities — often due to scarce forage or short pasture following dry summers
Signs typically appear 3–7 days after ingestion and may include:
- Constipation followed by black, tarry diarrhoea
- Abdominal pain, bloating, and poor appetite
- Dehydration, increased thirst, and weakness
- Frequent urination, jaundice, and rapid weight loss
- In severe cases: collapse and death within 24–72 hours
- Youngstock and animals with high milk intake may show symptoms earlier due to tannin concentration in milk
Treatment & Prognosis
There is no specific antidote. Supportive care includes:
- Activated charcoal to absorb toxins
- Fluid therapy (oral or IV) to support kidney function
- Laxatives and antibiotics to manage secondary infections
Unfortunately, once kidney damage occurs, prognosis is poor — with mortality rates up to 70%
- Fence off oak trees or avoid grazing in areas with heavy acorn fall
- Clear acorns regularly, especially after storms
- Ensure animals have adequate forage to reduce temptation
- Include acorn risk in your annual herd health plan
As always at the first signs please contact you vet as early treatment is critical to the survival of your animals
