It can be scary to think about how many poisonous plants your horse may encounter, and you could never eliminate all of them from his world. But you can take steps to limit the threats they pose:
• Provide ample forage. Horses who have plenty of hay or healthy pasture grasses are less likely to spend much time nibbling on plants that are less palatable. Keep an eye on the health of your pasture, and provide hay if the grasses are getting overgrazed or dying back due to drought or other factors. Some toxic weeds are more of a threat in early spring or late fall because they are green and growing when the grass isn’t. Drought can also stress grasses, allowing potentially toxic weeds to gain a firmer foothold and begin taking over a pasture.
• Monitor your hay. A number of plants remain toxic when dried and become a threat when cut into hay bales. Examine your hay as you serve it, and pick out any unusual-looking leaves or branches.
• Prevent boredom. Even well-fed horses may nibble at anything within reach when they are bored. Offering hay in slow feeders may make their rations last longer, so they will be less inclined to turn to other plants. Toys can also help keep their minds and mouths occupied when they’re not eating, and amenable companions can reduce stress.
• Remove serious threats. Deadly threats such as yew or oleander need to be removed from any properties housing horses. More moderately toxic plants can be left where they are, especially if your horses tend to leave them alone.
• Avoid letting your horse chew on unfamiliar plants. When you’re out on trail rides or at shows, inspect the area carefully before allowing your horse to take a grazing break. Learn to recognize the most serious threats in your area, and don’t let your horse eat anything you can’t identify.
the plants may cause a painful skin rash.
Note that stinging nettle is a different plant than horse nettle (Solanum carolinense), a member of the nightshade family that can cause excessive salivation, diarrhea or constipation, depression and colic when eaten; serious cases may be fatal. Horses tend to avoid horse nettle unless they have no other forage. (To read more on horse nettles, see “How Toxic Is This Weed?” Consultants, EQUUS 414.)
Locoweed is highly toxic. Various species of this plant, also called crazyweed, grow throughout the West and Southwest, often in dry, sandy soils. Most contain an alkaloid that inhibits sugar metabolism, causing a buildup of sugars that disrupts the function of the brain and other organs. Weight loss, sudden changes in behavior or temperament, ataxia and unusual gaits are often among the first signs. There is no effective treatment for locoweed poisoning, and the effects may be permanent.
Horses tend to be naturally finicky eaters, which is good news when they’re picking through all of the plants in the pasture in search of the sweetest grass. Your horse will avoid many serious threats all on his own. And by learning to recognize and avoid the plants that might still do him harm, you’ll be able to keep him even safer.