PERILLA MINT TOXICITY

Perilla Mint is known by many names -- beefsteak plant, Chinese basil, rattlesnake weed, purple mint -- but by any name, it kills goats and other ruminants and horses that eat it.

Perilla frutescens (L.) Britton, a member of the Lamiasceae (mint) family, is appearing in pastures across Tennessee, Mississippi, Indiana, and other states. Originally from Asia, it is considered an invasive species in the USA. Perilla Mint causes respiratory distress syndrome (panting disease). The plant contains ketones that cause lung inflammation and impair the exchange of gases involving in breathing. The flowers are the most dangerous, but the entire plant is toxic, even when baled into hay. The greatest risk comes when the goat consumes the live plant.

Symptoms appear within 24 hours of the goat's eating the plant. Heavy and loud breathing accompanied by open-mouthed panting occurs in severe cases. The goat may grunt in an attempt to expel air from its damaged lungs. Experiencing emphysema-like symptoms, the goat is oxygen deprived and unable to move around. The lungs may rupture, pushing air bubbles under the skin over the goat's back and neck. Mortality is high, but if the goat survives for 48 hours, it may recover; however, the damage done to its lungs usually guarantees chronic poor health. A necropsy of the body usually reveals Perilla Mint seeds in the stomach.

Perilla Mint can grow to a height of three feet, has hairy square stems, leaves that range from green to dark purple with serrated (saw-like) edges, a long and narrow seed head, and produces purple and/or white flowers from July to October. The plant usually grows in shaded areas but has been found in normally sunny locations when wet and overcast conditions occur. When crushed, the plant produces a minty scent. The Alabama Cooperative Extension System has a short YouTube video that is worth viewing for identification purposes. http://www.youtube.com/watch?v=f8ctYt658hA

The plant must be eradicated because once the goat eats it, there is no effective treatment. Eradication involves pulling or digging up plants in April through June when the plant is growing. Perilla Mint is very difficult to control in late summer to early fall, but mowing before it produces seeds helps reduce its spread. If you pull the plants by hand, use gloves to avoid contact with its toxic oils. Herbicides like 2,4-D, Milestone, Weedmaster, Grazon P+D, Remedy, Crossbow, or Banvel have been used successfully. Do not apply these products when humidity is high. Glycophosphate kills the plant but it also kills valuable forage.

Make sure your goats have good quality feed available to them if this plant grows on your property so that they won't be tempted to eat it. Animals that are properly fed normally will not eat Perilla Mint. At this point in time, there is no successful treatment for Perilla Mint toxicity. Prevention is your only option.

Suzanne W. Gasparotto, Onion Creek Ranch, Texas 10/5/14