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Strong winter bodes well for lupine and other poisonous plants

Monica Gokey for Progressive Cattleman Published on 24 May 2019
Lupie is a purple flowering plant

At the Eliason family ranch in Holbrook, Idaho, Brayden and Allison Eliason are checking first-calf heifers on a February morning last year when they find a stillborn calf with a cleft palate.

Where there should be a soft flap of upper lip, the calf has a jarring gap just below its nose.

“There’s no way he could’ve survived or suckled with a cleft palate,” Brayden says, adding that it’s fortunate the calf didn’t live.

A cleft palate is one of many congenital deformities lumped under the umbrella term “crooked calf disease.” Deformed bones and spinal abnormalities are other presentations of the same problem. Where the Eliasons live, on the northern tip of the Great Basin, crooked calf syndrome is often the after-effect of mother cows who ate lupine during the previous summer’s grazing season.

Lupine is a flowering legume common to the Rocky Mountain West. Several hundred strains are endemic across the Americas, but only a few are toxic to livestock.

Brayden says just a generation ago there weren’t many instances of crooked calf disease in their area, but the Eliasons and their neighbors are seeing more of it each year.

The danger

Grazing lupine-infested rangelands is an uncomfortable dance: Lupine is most dangerous during certain parts of the plant’s growth cycle – chiefly during flowering and after it’s gone to seed – and mother cows are most susceptible to its effects during days 40 to 100 of gestation. Learning to shoot the gap takes finesse, observation and a willingness to adapt.

Fortunately for stockmen, there’s a USDA-run facility entirely dedicated to poisonous plants research. The Poisonous Plants Research Lab in Logan, Utah, generates the science that helps guide how producers manage livestock around poisonous range plants from lupine to locoweed.

Moisture plays a role in how prolific it is in any given year. Since 2019 has been a bumper year in terms of winter precipitation, it bodes well for lupine (and other poisonous plants, too, like larkspur).

“Wherever lupine grows, there’s the possibility of crooked calf,” explains Jim Pfister, rangeland specialist at the Poisonous Plants Lab. “It’s a function of density and palatability.”

Lupine is probably most notable for its beautiful, flowery appearance in otherwise very dry rangelands. Its flowers can be purple, blue, white or pink. They look vaguely like the flower of a garden pea, blossoming up an entire flowering cone.

The dry, arid Channeled Scablands in eastern Washington are one of the most studied habitats when it comes to lupine’s effect on livestock. At one point in the mid-’90s, up to 25 to 30 percent of calves in the Scablands were born with crooked limbs or cleft palates or both, Pfister explains. Lupine was a major knock to the bottom line for stockmen there.

Poisonous Plants Lab research leader Daniel Cook, a plant physiologist by background, says lupine is a good forage at face value. It’s got roughly the same protein content as alfalfa, and it’s nutritious at a time of year when other plants are dry and mature.

“Lupine is typically not highly palatable,” Pfister adds. “It all depends on other forages present. (Cows) can prefer things like fiddleneck and skeletonweed before they will eat lupine. But if forage availability and quality becomes low, they’ll eat it.”

Around the time grasses start to dry up, and other forbs have been grazed, lupine starts to look more attractive to a hungry cow. In the Scablands, that time frame is mid-July, coinciding with an at-risk stage of gestation, 40 to 100 days, for mother cows on a conventional calving cycle.

Lupine acts as a sedative on gestating calves, which inhibits normal in utero movement. When calves stay still too long in the womb, they’re at risk of developing the kind of deformities lumped under crooked calf syndrome.

So how can ranchers prevent cows from eating lupine in the first place?

They often can’t prevent cows from eating it entirely. What they can do is try to mitigate the quantity of lupine consumed, and when it’s consumed in a mother cow’s gestation cycle. Producers in the Scablands have caught on.

“Some have delayed their spring breeding by a month or two so their cows enter into that 40- to 100-day pregnancy window later in the fall, when they’re much less likely to eat lupine,” Pfister says.

Others have switched entirely to fall calving to completely avoid any incidence of crooked calf. And yet others have put only yearlings on their most lupine-heavy rangelands. Yearlings aren’t affected by rangeland lupine.

Producers in the Scablands haven’t been able to erase the incidence of crooked calf in their herds, but they’ve been able to reduce it considerably.

“We estimate there are some large herds of beef cattle in eastern Washington that, as a background, have 3 to 5 percent occurrence of crooked calf year-in, year-out,” Pfister says. “Most ranchers in that area accept it as the cost of doing business.”

The challenge

Although producers in the Scablands know exactly what they’re up against, ranchers in other areas may not be clued in to poisonous lupine nearby until they start seeing deformed calves.

Most lupine across the West is innocuous to livestock. Some lupine species can contain one of two compounds that make it teratogenic. (Teratogenic means to cause abnormal embryo or fetal development.)

“Not all lupine species contain one or both teratogenic principles,” Cook says. “Within certain lupine species, some populations contain it, and some don’t.”

In other words: The exact same species of lupine can be toxic in one place and totally benign in another. It’s one of the most remarkable facets to the problem, and one of the hardest to troubleshoot.

In Oregon, for example, just 80 to 100 miles away from the Channeled Scablands, the same species of lupine that wreaks havoc on cattle herds in eastern Washington is a non-issue, Cook says. The why of this is a mystery scientists at the Poisonous Plants Lab are still trying to unravel.

Pfister and Cook are emphatic – there’s only one way to know whether a local strain of lupine is toxic or not: chemical analysis. It’s a service the Poisonous Plants Lab provides to ranchers for free.

“We encourage producers to make a collection of several plants of the same species,” Cook says. “Air-dry it, throw it in a paper bag, and send it to us.” Producers should send a single pressed plant containing the aboveground parts for identification purposes, too, he says.

In the event a rancher has a dead animal on their hands, tissue samples can also be sent to the Poisonous Plants Lab for analysis.

Eyeballs, in particular, are a favorite. “Alkaloids tend to hang around in the eyeballs for a while,” Cook explains. If ranchers are able to cut out an eyeball on a dead animal, Cook suggests freezing it before sending.

Pfister adds that sending a frozen sample of rumen contents is another way to get a diagnostic on whether poisonous plants contributed to an animal’s death.

As the West emerges from a wet winter, residual snowmelt will give life to grasses and other range plants livestock thrive on. It’ll also be a boon to the less desirable range plants producers share the range with.  end mark

PHOTO: Lupine is a purple flowering plant common to the Rocky Mountains. Photo by Monica Gokey.

Monica Gokey is a freelance writer located in Idaho.

Got poisonous plant problems?

Lupine and larkspur samples can be sent to the following address, with important information like a rancher’s name and contact info, the date and location of the material collected and whether or not there were dead or sick animals.

Dr. Daniel Cook
USDA-ARS Poisonous Plants Research Laboratory
1150 E. 1400 N.
Logan, UT 84341


The most common plant sent to the Poisonous Plants Lab for diagnostic testing is larkspur. Unlike lupine, whose toxic effects are projected onto a gestating calf, the effects of larkspur can be immediate and fatal in cattle. Larkspur thrives from foothills to mountain rangelands. In the worst hot spots across the West, herd mortality due to larkspur poisoning can verge on 10 percent.

Recent research at the Plants Lab is uncovering how different cattle are affected by larkspur as a function of age, sex and breed, explains Ben Green, research pharmacologist.

“In human medicine, scientists are studying things like how different people respond differently to drugs – men versus women, old versus young,” Green says. “We’re applying that framework to cattle and poisonous plants.”

Green’s research has yielded a number of valuable insights: Beef breeds like Angus, he finds, are more susceptible to the toxic effects of larkspur, whereas dairy breeds are less susceptible. Angus heifers are particularly vulnerable compared to steers and bulls. Younger cattle, in general, are more susceptible to larkspur poisoning than older cattle. All these insights will help equip producers with the right information to mitigate larkspur loss in their herds over time, mainly by allowing them to know which animals are most vulnerable to larkspur.

Larkspur poisoning presents as muscle weakness, lethargy and lying down.

If producers come upon cows in this condition in a patch of larkspur, there can be an inclination to move them out of it as soon as possible, Green explains. But moving cattle in haste can actually make the problem worse.

“If cattle are lateral-recumbent, try to get them on their brisket,” Green suggests. “You just have to keep (cows) alive long enough to metabolize the toxins.”

There’s an antidote for larkspur poisoning called neostigmine. Producers in larkspur country can ask their vet for a one-time injectable dose of neostigmine to keep in a saddle bag. Administering it to a cow suffering from larkspur poisoning can reverse symptoms, often saving the cow.

Like lupine, not all larkspur species are toxic. Chemical analysis is the only way to be sure.

Producers can shift the timing of grazing to mitigate potential losses due to larkspur. With abundant winter and spring precipitation, producers can expect to see abundant larkspur populations this year.