Keep animals away from midwestern toxic plants

Animals that spend time in corrals or pastures are at risk of eating toxic forages. Summertime, with its high temperatures, too much or not enough rainfall and agricultural chemical applications can heighten the risks, as they all can change the toxicity level of plants.

The Toxicology Department at the Kansas State University College of Veterinary Medicine has outlined common midwestern plants that can be hazardous to livestock if consumed or touched.

Poison hemlock is toxic to humans, birds, cattle, horses, sheep, goats, pigs and other wildlife. Livestock will rarely eat hemlock because of its strong odor. They will eat it if no other forage is available or if it is in hay or silage.

Signs of poisoning develop within an hour of consumption. Salivation, abdominal pain, muscle tremors and lack of coordination are the first signs, followed by breathing difficulty, dilated pupils, weak pulse and frequent urination and defecation.

If the animal has eaten enough poison hemlock, respiratory paralysis, coma without convulsions and, in some cases, death can occur. Poison hemlock can cause abnormal fetal development if it is eaten by cows between 40-70 days of gestation.

Water hemlock -- the toxin of this plant is concentrated in its tuberous roots, but the entire plant can be toxic. Livestock that eat the roots will most likely die. In the spring, the emerging plant is the most toxic.

The mature plant, in late summer, and the dry stems have minimal toxicity to cattle. This potent neurotoxin is capable of rapid onset of muscle tremors and violent convulsions. Death often occurs two to three hours after consuming a lethal dose, but it can occur as soon as 90 minutes after consumption.

Pigweed, most frequently red-footed pigweed, is typically found in cultivated and disrupted soils along roadsides and waste areas. It is also frequently found in and around corrals and other animal enclosures.

The most common problem with pigweed is nitrate toxicity. The blood becomes a chocolate color because it can't move oxygen from the lungs to the rest of the body. Thus, life cannot be supported.

Hairy vetch establishes in many areas, especially along roadsides, waste areas and in croplands. It is undetermined what makes this plant toxic. Hairy vetch poisoning occurs most often when the plant is near maturity and forms a major part of the diet of cattle and horses.

If livestock poisoning is suspected, carefully examine the grazing area for poisonous plants. Jimsonweed, snow-on-the-mountain, croton and wild indigo are commonly found in open areas of the pasture. Species commonly found in shady areas include white snakeroot, bracken fern, pokeweed and buckeye.

Moist areas along creeks or ditch banks are favorable for growth of black nightshade and horsetail, in addition to water and poison hemlock. Poisonous plants found in cultivated fields include cocklebur, jimsonweed, milkweed, pigweed and johnsongrass. Wild cherry, milkweed and pokeweed are found along fence and hedge rows.

Editor's Note: Delta George is a K-State Research and Extension agriculture and 4-H extension agent assigned to Bourbon County. She may be reached at (620) 223-3720.