University of Wyoming ecologist discusses death camas and larkspur poisoning
University of Wyoming (UW) Rangeland Extension Specialist Associate Professor and Rangeland Management Plant-Herbivore Interactions Ecologist Derek Scasta discusses taming death camas and larkspur poisoning, on March 13 and March 22, respectfully, in a series of YouTube videos titled, “Taming Toxic Plants.”
Taming death camas
Death camas is a native perennial bulb which is poisonous to livestock. Scasta notes its appearance is often confused with wild onion as it consists of linear grass-like leaves.
“Death camas is very common in Western rangelands, typically in what we would consider dry foothill ranges, ranging in a variety of soils – anything from sandy soils to rocky soils – and seldom above 8,000 feet,” he says.
Plants are often seen in groups of three, can be anywhere from four to 16 inches tall and have flowers ranging in a white to yellowish color in clusters elevated on the stock above the basal leaves, he explains.
Scasta notes according to the U.S. Department of Agriculture plant database, death camas is most likely present in every Wyoming county, and the species most producers are concerned with are the meadow, mountain, foothill and nuttall’s death camas.
The plant can also be found in Utah, Nevada, Idaho, Montana, the western two-thirds of Colorado and northern New Mexico and Arizona.
“All classes of livestock can be poisoned,” he says. “This includes sheep, cattle and horses.”
He mentions there have also been cases in which pigs, chickens and even humans have been poisoned.
Death camas, when consumed, releases a toxin called neurotoxic steroidal alkaloids, otherwise known as zygacine. The toxin causes hypotensive activity or lowering of blood pressure. It can also alter sodium ion channels up to 1,000 times slower, thus increasing sodium concentrations levels, leading to increased nerve and muscle excitability.
“In the plant material above ground, the toxin tends to decrease through the season. However, the toxin in the bulbs stays consistently high throughout the year,” says Scasta.
Consumption of death camas is a concern for spring grazing animals. Clinical signs and symptoms may include excessive salivation, bloody frothing, nausea and vomiting.
Other signs can include weakness, staggering, tremors, ataxia, prostration, fast and weak pulse, labored breathing, coma, congestion of lungs and kidneys, minimal necrosis of skeletal and cardia muscle and death within hours to a couple of days.
He explains it doesn’t take a whole lot of plant material to cause problems and kill animals. In sheep, it has been noted a 100-pound sheep can be killed by as little as one-half to two pounds of death camas material.
If there is evidence of ingestion of the plant, producers should consult their veterinarian. Two milligrams of atropine sulfate and eight milligrams of picrotoxin per 100 pounds of body weight is reported to be effective in treating early poisoning of sheep, mentions Scasta.
He says supportive therapy with intravenous fluids can also be helpful to combat hypotensive effects, and bloated animals should be kept in a sternal position and a stomach passed to relieve rumen pressure.
“As Wyoming heads into early spring greenup, now is the time to be paying attention,” Scasta mentions.
Larkspur poisoning
Larkspur is a native and naturally growing perennial. As the name implies, the flowers have a pedal spur on the back of the plant. The leaves tend to be deeply lobed with a palmate shape, Scasta explains.
“What is interesting about larkspur is it has also been cultivated for home gardens,” he says. “Sometimes this can cause issues.”
In North America, larkspur is present in the lower 48 states and up through Canada and Alaska. They grow in three different growth/habitat groups – tall larkspurs, low larkspurs and Plains larkspurs.
In Wyoming, larkspur is primarily an issue for cattle and rarely an issue for sheep and horses, but if subjecting animals to sudden physical activity after ingestion may lead to clinical effects.
There are many alkaloids in a larkspur plant, but the two prominent structural types are lycoctonine type and a 7,8-methylenedioxylycoctoine type. There can be regional differences in toxicity for a single species. Scasta explains these are called chemotypes.
He notes location can determine toxicity, and larkspur is a common native species on rangelands. At times, it can be highly palatable and problems occur in areas with high larkspur abundance.
Cattle most often consume larkspur after plants begin flowering, but some specific growth states can cause serious problems.
Consumption can increase in the pod stage. New growth and seed pods contain the highest concentration of toxins. In some parts of the West, low and Plains larkspur may be the only green herbage in early spring.
Like death camas, intoxication is generally an acute issue, as it doesn’t take a lot of plant material or time for animals to be impacted and die suddenly. Affected animals can be nervous, weak and/or stagger around.
Other signs may include muscular twitching, nausea and vomiting, bloat, rapid and irregular pulse and pulmonary congestion. Physical excitement can intensify signs of poisoning.
In terms of diagnosis, producers will want to see if larkspur is present on rangelands before turning livestock out to graze and observe animals frequently for clinical symptoms.
Treatment may include placing an animal on its brisket or chest with its head uphill to reduce bloating and avoid unduly excitement.
Producers will also want to consult with their veterinarian, but the cholinergic drug neostigmine, given at 0.02 milligrams per kilogram has shown to reverse clinical larkspur intoxication in controlled trials with repeated application every two hours.
As far as management, producers will want to consider grazing timing; graze with sheep; utilize alkaloid binding supplements, such as Silent Herder mineral and spray larkspur with herbicides.
Scasta notes herbicide application can sometimes increase alkaloid content.
“If we do spray, we want to wait until it’s completely desiccated and withered away before we graze animals there,” he says. “Although, spraying may not be an option, particularly on public lands and forest allotments.”
In closing, Scasta encourages producers to get in touch with their veterinarian if larkspur poisoning is suspected.
“As we go into spring, we’ve had a lot of snow, and I think there’s a big concern 2023 might be a big larkspur year,” he says.
Brittany Gunn is a corresponding writer for the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.
