After chronic ingestion (meaning they have to eat a lot of it over a period of time), signs may begin to appear. The toxins in yellow star thistle affect a specific area of the brain which affects the horse's ability to take in food. They are able to use their incisors to pull food into their mouth, but they cannot move it back to their molars. They will show difficulty when trying to drink and may progress to further neurologic signs, such as depression, ataxia and circling. No specific treatment is available other than supportive care. Affected horses do not recover, however they may be able to learn how to deal with their difficulty.
Ingestion of hoary alyssum can lead to several generalized symptoms that begin to arise 18-36 hours later. These include lethargy, fever and occasionally diarrhea. Stiffness of the joints and laminitis are also possible sequelae. Symptomatic and supportive care are provided for treatment and signs typically resolve within 5 days after the removal of the plant from the diet.
For more information on hoary alyssum, check out this site from the MSU Extension.
Cherry trees are easily identified in the spring, when they blossom. (Just think of all the tourists that go to Washington, DC in April!) The attractive white or pink flowers are present in clusters of three to five. The oval shaped green leaves are pointed at the tip and have serrated edges along their 3-5 inch length. They surface is shiny and smooth in texture.
Signs of cyanide toxicity can occur quickly, and often times it is too late by the time a veterinarian arrives. The cyanide interacts with enzymes in the body, which prevents oxygen from entering cells. Once the tissues are deprived of oxygen, the body begins to shut down. This can lead to an elevated heart rate, increased respiratory rate, and even seizures. While there is an antidote, death can occur within minutes of ingestion of the toxic principle.
Humans can be affected by this plant if they ingest milk from an animal that was grazing on it. Just ask Abraham Lincoln's mother! If an animal (let's say a horse, for example) eats it, they can become weak, depressed and develop trembling and sweating. In severe cases, it can lead to recumbency.
As with many of these plants, supportive care is the mainstay of treatment for white snakeroot ingestion. Horses usually recover after removal from the source and therapy, however there is the possibility of long lasting cardiac damage.
In the next installment, we'll be talking about some less scary plants which might be scattered around your fields.
Just like last time, here's a link to the Texas A&M Extension's list of sites.