Adelle Crofford, DVM and Rosslyn Biggs, DVM-
Toxin exposure can cause rapid life-threatening events in livestock. Cattle can encounter toxins from many sources. The most common route of toxin exposure is ingestion. It is beneficial to think about what the herd is eating and drinking, as well as the sources, distribution, storage, and handling of each. Animals typically have a natural aversion to toxic plants due to palatability, however, in times of scarcity, such as drought, livestock may consume plants previously left untouched.
As drought conditions continue, producers may find themselves operating outside of the norm, using previously unused pastures or incorporating new management techniques. Changes to a routine may increase the risk of toxin exposure. It is important to assess potential hazards as changes develop.
As with most herd health issues, preventative measures are the best way to save livestock and money. Knowing and understanding all aspects of an operation is important so problems can be identified before they happen and can be tracked down quickly when they occur. Adding toxicity considerations to biosecurity plans can help prevent issues.
When assessing sources of exposure, consider dividing the potential routes into three categories: pasture exposure, water sources, and feed sources.
Regular evaluations of pastures and current conditions can mitigate toxin exposures. Producers should consider what grasses and other plants make up pastures. Certain plants can be toxic during times of rapid growth or stress, and there are management strategies that can mitigate risk. For instance, if prussic acid is a concern due to young Johnson grass growth, ensure cattle are recently fed before turning out and ideally avoid these pastures altogether. Herbicide application may also increase palatability of some toxic plants. Tree and shrub trimmings should not be fed as many toxic plants may be used for landscaping purposes. Additionally, cattle can encounter other toxins on pasture, such as lead from improper disposal of vehicle batteries.
Water can also serve as a source of toxins. Contamination can be the water source itself or the re-use of containers or tanks for water previously for other things, like fertilizer application.
Similar to water, feed storage containers and distribution methods should all be considered as potential sources of exposure. Feed storage conditions should be regularly evaluated to prevent mold growth.
When any animal is exposed to a toxin, clinical signs are typically observed as a rapid onset of severe symptoms. Although there are many ways toxins affect the body, toxic changes are more quickly seen in the nervous system. The following clinical signs may suggest toxin involvement:
o Multiple animals affected with similar signs or similar disease progression
o Sudden death
o Abortions or unexpected loss of pregnancies
o Animals of different ages affected
o Recent management changes as they relate to water/feed/nutrition
o Neurologic signs (ex. seizures, convulsing, behavioral changes, or death)
o Multiple organ systems affected
o No clear infectious pattern (typically no fever)
If toxin exposure is suspected, remove the source of the contamination by moving cattle from the location or cease feeding the suspected ingredient. A veterinarian should be contacted to collect samples for submission to a diagnostic laboratory. The laboratory will typically advise which samples to take and testing availability. The suspected source of the toxin should always be submitted if available. Prevention of toxin exposure and rapid mitigation are important keys to avoiding life-threatening livestock events.
*Dr. Adelle Crofford is a 2026 OSU College of Veterinary Medicine graduate and is pursuing a toxicology residency at Kansas State University.
