- Erect, densely haired annual growing to 3 feet in height. Leaves are alternate and narrow. Flowers are white; pods are round and slightly flat.
- Geographic range
- Invasive weed of waste areas and roadsides found across North America. Often grows in alfalfa fields.
- Toxic principle
- Toxin has not yet been identified.
- Horses become intoxicated after eating green or dried plants. When mixed with alfalfa hay, B. incana can remain toxic for up to nine months. The toxic dose has not been determined.
- Clinical signs
- Early manifestations of intoxication are laminitis and limb edema, which cause lameness. Signs associated with severe intoxication include stiffness, fever, diarrhea, intravascular hemolysis, hypovolemic shock, and death secondary to endotoxemia. Premature parturition or abortion may occur in pregnant animals.
- Subcutaneous edema, pulmonary edema, and edema of kidney interstitium are seen. The mucosa of the stomach and small intestine may be ulcerated with small areas of hemorrhage. Large amounts of calcium carbonate crystals may be found in the bladder.
- Treat symptomatically for laminitis and shock. Most treated horses will recover.
- Examine alfalfa hay to make sure it does not contain hoary alyssum.