Hoary alyssum: the most common poisonous plant to horses in Minnesota (2024)

FAQs

Hoary alyssum: the most common poisonous plant to horses in Minnesota? ›

Hoary alyssum can cause depression and swelling of the lower leg in some horses. These signs occur 12 to 24 hours following intake from hay or pasture. In more severe cases, animals show an apparent founder with stiff joints and refuse to move. Hoary alyssum is widespread across Minnesota and toxicity is common.

Quick facts. Don't feed hay containing hoary alyssum to horses. Hoary alyssum is common in disturbed areas, meadows, pastures and hay fields. It's toxic in fresh pasture or dried in hay and causes “stocking up,” fever and founder.

Hemlock (Conium maculatum)

The danger: Hemlock leaves, stems and seeds contain several potent neurotoxins that affect both the central and peripheral nervous systems. Four to five pounds is a lethal dose for a horse.

Herbicide control can be done using systemic herbicides which are taken up by plants and move within the plant, which can kill leaves, stems, and roots. Herbicides that can be effective on hoary alyssum include 2,4-D and glyphosate.

The degree of danger a poisonous plant represents is a function of the plant's prevalence, toxicity, and palatability. If good quality forage is plentiful in the pasture, horses will avoid most poisonous plants.

Signs and Symptoms: Just under 50% of horses that are ingesting Hoary Alyssum will show signs of toxicity. Typical beginning signs are “stocking up” of their lower legs or what looks like swelling, a high fever, warm hooves, laminitis, stiffness of joints, reluctancy to move, and in severe cases death.

1: Oleander

The oleander, or Nerium oleander, is considered by many to be the most poisonous plant in the world. All parts of the beautiful oleander contain poison — several types of poison. Two of the most potent are oleandrin and neriine, known for their powerful effect on the heart.

Tobacco (Nicotiana tabacum)

Tobacco use causes more than 5 million deaths per year, making it perhaps the most deadly plant in the world.

Water hemlock is considered to be the most deadly plant growing in North America. It is common in moist areas in meadows, marshes, ponds and even roadsides.

Is white top poisonous to horses? ›

Hoary Allysum, also known as hoary mustard or white top, is a common weed that can be toxic if ingested. The plant contains nitrate, which can accumulate in the horse's body and cause nitrate poisoning. Symptoms include weakness, rapid heartbeat, difficulty breathing, diarrhea, and collapse.

Hoary alyssum is an invasive species. Hoary alyssum displaces native species in dry prairies and sand blowouts where vegetation is sparse.

No cases of hoary alyssum toxicity in ruminant animals (dairy, beef, sheep or goats) have been reported to date. Some horses, however, have shown a response to this weed.

🐾 Veterinary Insights on Sweet Alyssum

It's non-toxic to dogs, and its flowers are even edible for humans. No need to panic if Fido takes a nibble.

All plant parts of Hoary Alyssum are toxic to equines. Retains toxicity when dried such as in hay products. The toxin is not yet identified, however, reports state that 30% or more in hay has caused severe toxicity or death in Equines.

Answer. Purple deadnettle (Lamium purpureum) is no stranger to pasturelands, roadsides, lawns, and gardens. As the photograph shows, this winter annual features bright pinkish-purple flowers and serrated, spade-shaped leaves. Those leaves nearest the flowers often have a purple cast but will turn green as they mature.

Sudan grass and its hybrids are often grown as a forage crop for horses and cattle. Animals consuming them in either fresh or dried form may suffer cyanide poisoning. Both Johnson and Sudan grasses may contain hydrocyanic acid (prussic acid) and sometimes toxic levels of nitrates.