Identifying & Avoiding Toxic Plants for Sheep 

After spotting a stand of johnsongrass in the sheep pasture, this shepherd got serious about protecting her flock from toxic plants.

by Jana Wilson
PHOTO: stockphoto mania/Adobe Stock

Anyone who owns sheep wants to keep them as healthy and happy as possible … right? Ensuring their health and well-being  is essential for sustainable farming practices. Curious about the plants in my pasture, I discovered an app called Picture This for my iPhone that is probably the best one I have found (and I have tried many) for identifying grasses and other plants out in a pasture.  

In addition to knowing which plants are the most nutritious, another crucial aspect of sheep care is understanding and preventing their exposure to poisonous plants. I struggled with identifying grasses, for instance, and just didn’t feel confident that my pastures were offering the best nutrition. 

Safety First

Maintaining a safe environment for sheep is a top priority for any shepherd or livestock owner. Being knowledgeable about poisonous plants can help prevent potentially fatal incidents in your flock. By understanding the types of plants that can harm sheep, you can take proactive measures to ensure their safety. 

It all started when, after purchasing my plant app, I grew curious about the really tall, wide-leafed grass plant up by the front of one pasture.  To my dismay, the plant was johnsongrass (Sorgham halepense), which is a species of sorghum.  According to the Ohio State University Sheep Team, sudan grass and sorghums are cyanogenic plants. These plants are usually deadly when damaged or frozen. Under conditions like this, the plants contain prussic acid (hydrocyanic acid), a deadly poison that interferes with the oxygen-carrying ability of the blood.

toxic plants sheep
Jana Wilson

Death in these cases is usually rapid and with little outward symptoms. After discovering that, I plan to cut down the small patch that I have before it goes to seed and try to contain it that way. 

Every part of the country is different, but it’s good to know what you have in your pasture, whether you use a phone app or consult your county extension agent.   

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The Danger List 

Johnsongrass isn’t the only plant on the toxic list, though. Though your area may have more or different dangerous plants, here are a few more plants that are toxic to sheep that I keep an eye out for. 

Buckthorn (Rhamnus spp.)

Buckthorn is a shrub that is toxic to sheep. Its leaves and fruit contain compounds that can lead to gastrointestinal distress and even death in severe cases. It’s crucial to identify and remove buckthorn from grazing areas to prevent accidental ingestion by sheep.

Nightshades (Solanum spp.)

Nightshades, including plants like horsenettle and black nightshade, are known for their toxic effects on sheep. Unfortunately, I have quite a bit of horse nettle in part of my pastures. I dig them up as soon as I find them!  

These plants contain solanine, a poisonous alkaloid that can cause a range of symptoms such as drooling, diarrhea and convulsions. Regular monitoring of grazing areas can help prevent sheep from consuming nightshades. 

Hemlock (Conium spp.)

Hemlock is a highly toxic plant that poses a significant risk to sheep. Ingesting even small amounts of hemlock can lead to paralysis and respiratory failure. Identifying hemlock and removing it from pastures and foraging areas is essential to safeguarding sheep from this deadly plant. 

Foxglove (Digitalis purpurea)

Foxglove is a beautiful but poisonous plant that contains cardiac glycosides. Ingesting parts of the foxglove plant can cause heart irregularities, vomiting and death in sheep.  

Pasture Management 

It’s a really good idea to inspect and maintain grazing areas, as it is crucial to prevent sheep from encountering poisonous plants. Take a walk around your pastures and look for toxic plants.   

Installing sturdy fencing around grazing areas can help prevent sheep from accessing potentially harmful plants. This physical barrier can be an effective way to keep sheep away from toxic vegetation … even though your pasture is safe, the areas outside the fence may not be. 

As I mentioned before, your local agricultural extension offices often provide resources and expertise on plant identification and management. Connecting with these offices can help you access region-specific information to protect your sheep from toxic plants. 

Ensuring the health and safety of sheep really requires a comprehensive understanding of the poisonous plants that can pose a threat to them. I encourage you to look on your own at sites like the Ohio State University Sheep Team, where you can get a fuller idea of what plants you need to watch for. 

By staying informed about these plants and implementing preventive measures such as proper pasture management, fencing and education, you can create a safer environment for your flock. Proactive management really is key to maintaining the well-being of your sheep! 

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