Signs and lesions of lupine poisoning:

  • Nervousness
  • Excessive salivation, frothing at the mouth
  • Depression
  • Reluctance to move about
  • Lethargy, inappetence
  • Difficulty in breathing
  • Twitching leg muscles
  • Loss of all muscular control
  • Convulsions
  • Coma
  • Death

The greatest risk of lupine is “crooked calf syndrome,” caused by pregnant cows or heifers grazing certain lupines during late first trimester or early second trimester. The species of lupine and the alkaloid profile is required to evaluate risk. Cows may give birth to calves with cleft palate and skeletal defects if the cows ingest certain lupines during early gestation (crooked calf syndrome), during the 40 th to the 100 th day of gestation.

Poisonous species of lupine are toxic from the time they start growth in spring until they dry up in fall. Younger plants are more toxic than older plants; however, plants in the seed stage in late summer are especially toxic because of the high alkaloid content of the seeds. Lupines are legumes and are relatively high in protein, especially the seed pods, and may become a preferred forage species when grasses become mature and dry. Under proper conditions, some lupines make good forage.

Where and when lupines grow:

Lupines grow on foothills and mountain ranges in sagebrush and aspen areas. Lupine populations expand during wet seasons and may die back during dry seasons. The seed reserve in the soil remains high and when environmental conditions are optimum lupine population will increase.

How lupines affect livestock:

The amount of lupine that will kill an animal varies with species and stage of plant growth. It is not safe to let sheep freely graze certain species and the early flower/seed pod stage of plant growth is especially dangerous.

Overt poisoning in cattle occasionally occurs if cattle lack other feed. Signs of poisoning and resultant death depends on the alkaloid content of the plant, how rapid the lupine is ingested and for how long. Smaller amounts may be poisonous if cattle eat lupine daily for 3 to 7 days. The major issue for cattle is the birth defects (crooked legs, spine or neck and/or cleft palate). Pregnant cows/heifers must graze some lupine over multiple days during the sensitive stages of pregnancy (40-100 days for cleft palate and skeletal deformities, or 40-50 days for cleft palate only) for deformities to occur.

How to reduce losses:

Poisoning can be reduced by keeping hungry animals away from lupines in the early growth stage, in late summer when the plant is in the highly toxic seed stage, and from dense plant stands at all times. Supplemental feeding is beneficial, especially when animals are trailed through lupine ranges. If animals are poisoned on lupines, do not try to move them until they show signs of recovery.

If cows in the susceptible gestational period (40th to 100th days of gestation) are kept from lupine when it is most teratogenic (very early growth or mature seed stage), most deformities can be prevented. The congenital deformity hazard is minimal at other gestation periods and after seeds have shattered from pods. The malformations can be avoided by adjusting the breeding season and the grazing of lupine-infested range to avoid the critical periods of gestation.

There is no known treatment for lupine poisoning, except removing the animal from the source and keep the animal calm until recovery occurs..

Lupine can be controlled with 2,4-D (2 lbs. ae/acre), 2,4-D + dicamba (1 + 0.5 lbs. ae/acre), or triclopyr (0.5 to 1.5 lbs. ae/acre). Spray actively growing plants after they are 5 in. high but before they bloom. Reinvasion is rapid and retreatment may be necessary every 4 to 5 years.