University of Minnesota Extension
Day One: Black Walnut
Identification: Black Walnut trees are massive with a round and symmetrical canopy appearance. The bark is dark brown/ black in appearance. Black Walnut trees flowers (from April to June), create a large editable nut (ripen in September or October), and usually drops its leaves shortly after the nuts ripen. When bark for a Black Walnut tree are cut for shavings they appear a lot darker then the usual pine shavings.
Habitat: Black Walnut trees prefers to grow in moist, well draining soils, and along rivers and streams.
Signs and Effects of toxicosis: The actual toxic component of the wood is unknown. Signs to look for are depression, limb edema, warm hooves, acute laminitis, stiff gait, and even signs of colic. These signs can be seen as quickly as a few hours of exposure. All it can take is bedding that contains as little as 20% black walnut. The common cause of toxicity is ingestion of the shavings, but some horses can have reaction just by skin contact with it.
Treatment: The symptoms of exposure will start to diminish once the contaminated bedding has been removed. Contact your veterinarian is you are seeing signs of exposure, especially if signs of colic or signs of laminitis are being seen. Anti-inflammatory drugs can be used to treat the pain with additional drugs needed to treat any colic and laminitis.
Day Two: Endophyte-Infected Tall Fescue
Identification: There is no way to determine the difference between endophyte infected fescue and none infected fescue with the naked eye. Tall fescue can reach 48 inches in height or more. The fescue leaves are numerous, dark green, and have a shinny appearance to them. Endophyte-free grass can be fed or grazed by horses.
Habitat: Commonly found in pastures and hay fields. They can even be grown on poorly-draining soils.
Signs and Effects: Common syndromes that are associated with a ingestion of endophyte-infected fescue have the largest impact on pregnant mares. Mares that ingest infected fescue can result in prolonged gestation, difficult birthing, thickened placenta, infection, foundering, little to no milk production, and decreased colostrum levels. In non-pregnant mares it can cause vasoconstrictive effects that can cause damage or loss of feet, ears or tail.
Treatment: The best treatment is actually prevention. By mowing tall grass or watching the grass seed that you purchase. Pregnant mares should be removed from any hay or pasture that has endophyte-infected fescue at least 45 days prior to foaling.
Day Three: Brakenfern
Habitat: They can be found in open pastures and woodlands, particularly on acidic ground throughout the United States.
Signs and Effects: Side effects of ingestion of Brakenfern are depression, constipation, and unsteady gait as quickly as one to two days after ingestion. Effects can progress to muscle twitching, going down, and seizing for a period of a week.
Treatment: Treatment is administration of Thiamine for up to five days.
Day four: Yew
Habitat: Yews can grow in shade or sunny areas. They prefer fertile, well-draining areas, where they will get constant moisture.
Signs and Effects: Animals may be found dead due to many of clinical signs do not become exhibiting signs till 12 hours after ingestion. Muscle weakness is the first clinic sign that is observed. Heart beat become irregular the toxin builds up in the body. Terminal seizures will be observed before the horse drops to the ground.
Treatment: Treatment is not usually not an option due to how quickly death on sets. If caught early enough the veterinarian should be called and charcoal and mineral oil should be administered. Treatments are also focused on the heart and to maintain cardiac output.
Day five: White Snakeroot
Identification: White snakeroot grows one to three feet tall and branched and flowers at the top. The mature leaves have toothed edges and taper down to a point. The white flowers on the top of the plant are small and grow in clusters.
Habitat: It grows in heavily wooded areas where it is damp and shady.
Signs and Effects: Horses develop difficulty swallowing, muscle trembling and a park out stance with their head hanging close to the ground. As the condition progresses skeletal and heart damage occurs to the point where the horse will have difficulty standing.
Treatment: Prevention is the best treatment, by removing any white snakeroot source in the hay or pasture. Your veterinarian can administer active charcoal that could limit the amount of absorption.