Toxic Principle

The toxic principle of Tansy mustard or flix weed is not known. The plant is most often eaten when it is young and succulent, and it is at this stage that it is most toxic. The toxicity of the plant varies from year to year. The neurological signs seen with tansy mustard poisoning are suggestive of sulfate poisoning.

Description

Annual or biennial weed growing up to 3 feet in height and branching above. Leaves alternate, hairy, 2 or 3 times pinnately compound, each segment very narrow and linear. The flowers are produced terminally on the branches in slender racemes, each flower being small (1-2mm), yellow to green in color. The seed pods are slender, cylindrical, 1-2cm long, ascending, with 2 compartments, each with a row of seeds. Descurainia pinnata (tansy mustard) is very similar in appearance to flixweed except the seed pods are usually less than 1cm in length.

Gastrointestinal

Difficulty chewing and swallowing because the animal's tongue appears to be paralysed.

Musculoskeletal

Weight loss

Treatment

Most animals will recover if removed from the tansy mustard or flixweed. Severely affected animals need symptomatic treatment including water and electrolytes via stomach tube. large doses of thiamin may help resolve the blindness.

Nervous System

Blindness, head-pressing is seen in some animals.

Integumentary System

Severe photosensitization occurs in cattle grazing Flixweed and tansy mustard in early Spring.

Ocular System

Blindness

Hepatic System

In cattle with photosensitization, the liver enzymes are elevated indicative of a toxic hepatopathy.

Special Notes

Flixweed is common in alfalfa fields, and can therefore comprise a significant portion of first-cutting alfalfa. Flixweed and tansy mustard are not nutritious, and thus devalue alfalfa hay they contaminate. Flixweed is easily controlled with appropriate herbicides.