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While the goal of every horse owner is to have large fields with lush, green, belly deep grass free of weeds and toxic plants for their horses, that isn’t always realistic. A variety of plants grow in the areas that house horses, and it can be confusing to identify every plant they may be interested in eating. However, it is important to know what plants are poisonous and how to prevent them from becoming a problem.
Sara Mastellar has her PhD in equine nutrition and is currently an associate professor and Equine Programs coordinator at the Ohio State ATI (Agricultural Technical Institute) in Wooster, Ohio. She said poisonous plants rarely cause issues for horses unless there is not enough proper feed or forage available. She notes that some horses may ingest things they should not, particularly young or curious horses.
“Boredom and deficiency are other reasons horses may ingest poisonous plants,” Mastellar said. “Prevention is best. If you suspect that your horse is experiencing a toxicity, contact your veterinarian immediately.”
Kathy Whitman, DVM, MS, DABVP, is a Veterinary Extension Specialist at Colorado State University in Fort Collins, Colorado. She said the primary reason horses may eat toxic plants is poor pasture management.
“When we allow overgrazing, both noxious and toxic weeds become more capable of growing and establishing,” Whiteman said. “Plus, when there’s less grazable forage available to horses and livestock, the need to consume any available plant increases. Drought exacerbates this situation, and we’re experiencing that in many Western regions. Appropriate pasture management, and drought mitigation strategies, are the best methods to reduce risk of toxic plant exposure.”
Both experts share their knowledge on poisonous plants in this Barrel Horse News Q&A.
Horses are more selective than say, cattle, so their risk is relatively low on well-managed pastures. The risk for toxic plant consumption increases as good quality forages are less available (overgrazed), pastures are over-stocked, or weather conditions, such as drought or even deep snow that only allows access to toxic plants growing above snow, such as sage.
Sara Mastellar: Plants poisonous to horses vary by region. Some plants that cause issues in one area of the country are not found in others. For example, locoweed only grows in the western U.S., and hoary alyssum is commonly problematic in the upper Midwest (e.g., Minnesota). Here in Ohio, we have an abundance of poison hemlock (Conium maculatum).Some ornamental plants are present in many regions and are highly toxic (e.g., yew, rhododendrons (azaleas), oleander). I recommend reaching out to your local extension office to get a list of plants of concern in your area. Some extension personnel will also come out to your farm and help you scout for problem species. Additionally, some universities also maintain poisonous/toxic plant databases and the USDA maintains a database with distribution data for range maps for plants.
Whitman: There is a long list of potentially toxic plants in all animals, so I would encourage using the resources below to identify potential risks in your area. That said, here is a list of more common toxic plants in horses, as well as plants that can accumulate toxic levels of selenium (important toxin in horses) and nitrate (horses are more tolerant than cattle). Although this is not an exhaustive list, many of these are widespread across the US
TOXIC
SELENIUM ACCUMULATORS
NITRATE ACCUMULATORS
OTHER NOXIOUS WEEDS AND PROBLEM PLANTS
Mastellar: Symptoms vary widely. Everything from an unsteady gait, dark urine, colic, to even death can be symptoms of poisonous plant ingestion. Acute laminitis can be caused by contact with black walnut shavings. Carefully observing your horse’s environment and feed can help you and your veterinarian narrow down the potential cause of your horse’s symptoms. Depending on the symptom(s) there may be differential diagnoses to rule out.
Kathy Whitman: Colic is a frequent sign, immediately recognized, and readily treatable; conversely, more serious cases of neurological signs, like with locoweed, may be more dangerous if not caught immediately and have a poorer prognosis. Adults may not always be affected, but congenital deformities in foals can occur, such as cases of endophyte-infected fescue grass consumption.
In situations where odd clinical signs, like excessive slobbering or discomfort in the mouth are evident, irritating plants should be considered. Feces that smell of sage is an obvioussign of sage brush consumption and potential toxicity, and horses should be removed from access immediately.
Exposure to selenium accumulating plants is not noticeable right away, but with ongoing consumption results in horizontal cracks in hooves, poor hair coat, broken hair in mane and tail. In some cases, death may be the only clinical sign seen. Veterinary assistance in the cases may be the only way to identify the causative plant, and even then can be challenging.
Whitman: Horses are more selective than say, cattle, so their risk is relatively low on well-managed pastures. The risk for toxic plant consumption increases as good quality forages are less available (overgrazed), pastures are over-stocked, or weather conditions, such as drought or even deep snow that only allows access to toxic plants growing above snow, such as sage.
In situations where movement to a brand new pasture is occurring, I recommend, for any grazer, that they not be released on the pasture when hungry. This reduces the chance of indiscriminate consumption, and horses especially will continue with their selective grazing habits.
Mastellar: Scouting and awareness are key. Management and control strategies vary depending on the species of plant. Sometimes promoting desired forage species (i.e., grasses and legumes) is enough to crowd out problematic plants. Exercise paddocks, and dry lots should be scouted often due to not having good forage cover to outcompete potentially harmful plants. Mowing before seed formation can help in some cases.
Effective control methods can be different depending on the season and where the plant is in its life cycle. Trees and shrubs can be removed manually and most will not regrow. Work with your local extension personnel to identify plants of concern and the best ways to eradicate them. Thoroughly read the labels on any herbicides used. Be sure to allow for any grazing restrictions and residual effects.
Walk pastures and fencelines regularly, particularly after storms. The branches and leaves of some tree species become sweet and poisonous when wilted. The risk of poisoning increases when a storm big enough to break branches or topple trees goes through.
Also be aware of what’s in your hay. Know what desirable species look like in your hay and purchase from a reputable seller. Weed seeds from contaminated hay can grow in pastures where it is fed. While looking for poisonous plants, also keep an eye out for injurious plants, such as burdock or foxtail and remove them at the same time.
Also be aware of what’s in your hay. Know what desirable species look like in your hay and purchase from a reputable seller. Weed seeds from contaminated hay can grow in pastures where it is fed. While looking for poisonous plants, also keep an eye out for injurious plants, such as burdock or foxtail and remove them at the same time.
Whitman: Absolutely! Most toxic plants are dose-dependent, meaning that there is a threshold or tolerance for a certain level. Once the animal goes over that level, then it becomes a problem. In most cases, a mouthful of a toxic plant, or accidental ingestion isn’t an issue, or may only result in minor issues. In the case of something like water hemlock, however, it can be fatal very rapidly at small doses.
There are also instances where horses can develop some tolerance to what we would consider toxic plants. I’ve seen some horses have no problem with bindweed, but those same horses have access to other forages and have had time to adapt to bindweed as it’s grown. That said, we should never rely on a horse “adapting” to toxic plant exposure — again, they all have a toxic dose.
Identification of any toxic plants on your pasture is important for this very reason. If you see a few toxic plants that have a high tolerance level, then pasture management may be the only strategy required. On the other hand, if a low threshold toxic plant is identified, or a large number of any toxic plant that may be a risk, then other control strategies may need to be considered.
Mastellar: Yes, contact your veterinarian. They are the best resource for treating a suspected poisoning and treatment will be different depending on the plant, amount consumed, and other factors. As you are reaching out to a veterinarian, remove the suspected source of poisoning to prevent the case from getting even worse. Quickly contacting a veterinarian can give you more options as there may be treatments to reduce absorption of toxins from material already ingested. Continue to work with your veterinarian on a recovery plan that considers the details of your horse’s particular case.
Whitman: If caught in the early stages, routine medical treatment can be effective. Horses that show colic signs can benefit from decontamination, or essentially flushing the gut, and fluid support. Removal from plant exposure is key. Some neurological effects may take longer to recover, and in the case of such plants like Russian Knapweed and Yellow Star Thistle, those signs may never resolve. Some plants like water hemlock are almost always fatal, so if you do find a deceased animal in your pasture, consultation with your veterinarian and performing a necropsy as soon as possible is important, particularly if other horses are on the same pasture. If acute plant toxicity is the cause of death, that plant material may be found in the digestive tract.
Whitman: While we often want to blame unexplained illnesses on something like a toxic plant, it’s important to remember that plants toxicities cause things like colic, neurological signs, and sudden death, just like a lot of other diseases. The signs of toxic plants are not specific, so working with your veterinarian to determine causes of illness is important. Being able to identify toxic plants, particularly early in the growing season, is an important step in keeping your horses safe. I often use Google to snap a photo of a plant I’m unfamiliar with to get some idea of what it may be. And finally, never hesitate to reach out for help. There are local Extension and State specialists in your area that have expertise in local plants and can help you address issues as they arise.
CSU College of Veterinary Medicine and Biomedical Sciences Guide to Poisonous Plants
USDA ARS Poisonous Plants Research Laboratory
Diagnostic Laboratories Plants: CSU Plant Diagnostic Clinic ($25 per identification)
Diagnostic Laboratories Toxin screening: Cornell Veterinary Diagnostic Lab
The post Don’t Let Them Eat That: Toxic Plants appeared first on Barrel Horse News.
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Equine nutrition experts share how to identify toxic plants, what to do if your horse eats them and how to prevent future problems.
While the goal of every horse owner is to have large fields with lush, green, belly deep grass free of weeds and toxic plants for their horses, that isn’t always realistic. A variety of plants grow in the areas that house horses, and it can be confusing to identify every plant they may be interested in eating. However, it is important to know what plants are poisonous and how to prevent them from becoming a problem.
Sara Mastellar has her PhD in equine nutrition and is currently an associate professor and Equine Programs coordinator at the Ohio State ATI (Agricultural Technical Institute) in Wooster, Ohio. She said poisonous plants rarely cause issues for horses unless there is not enough proper feed or forage available. She notes that some horses may ingest things they should not, particularly young or curious horses.
“Boredom and deficiency are other reasons horses may ingest poisonous plants,” Mastellar said. “Prevention is best. If you suspect that your horse is experiencing a toxicity, contact your veterinarian immediately.”
Kathy Whitman, DVM, MS, DABVP, is a Veterinary Extension Specialist at Colorado State University in Fort Collins, Colorado. She said the primary reason horses may eat toxic plants is poor pasture management.
“When we allow overgrazing, both noxious and toxic weeds become more capable of growing and establishing,” Whiteman said. “Plus, when there’s less grazable forage available to horses and livestock, the need to consume any available plant increases. Drought exacerbates this situation, and we’re experiencing that in many Western regions. Appropriate pasture management, and drought mitigation strategies, are the best methods to reduce risk of toxic plant exposure.”
Both experts share their knowledge on poisonous plants in this Barrel Horse News Q&A.
Horses are more selective than say, cattle, so their risk is relatively low on well-managed pastures. The risk for toxic plant consumption increases as good quality forages are less available (overgrazed), pastures are over-stocked, or weather conditions, such as drought or even deep snow that only allows access to toxic plants growing above snow, such as sage.
Barrel Horse News: What are the most common toxic or poisonous plants that horse owners should be aware of? Are they found in a certain region or across the country?
Sara Mastellar: Plants poisonous to horses vary by region. Some plants that cause issues in one area of the country are not found in others. For example, locoweed only grows in the western U.S., and hoary alyssum is commonly problematic in the upper Midwest (e.g., Minnesota). Here in Ohio, we have an abundance of poison hemlock (Conium maculatum).Some ornamental plants are present in many regions and are highly toxic (e.g., yew, rhododendrons (azaleas), oleander). I recommend reaching out to your local extension office to get a list of plants of concern in your area. Some extension personnel will also come out to your farm and help you scout for problem species. Additionally, some universities also maintain poisonous/toxic plant databases and the USDA maintains a database with distribution data for range maps for plants.
Whitman: There is a long list of potentially toxic plants in all animals, so I would encourage using the resources below to identify potential risks in your area. That said, here is a list of more common toxic plants in horses, as well as plants that can accumulate toxic levels of selenium (important toxin in horses) and nitrate (horses are more tolerant than cattle). Although this is not an exhaustive list, many of these are widespread across the US
TOXIC
- Larkspur—can be fatal horses moderately sensitive
- Water and poison hemlock—fatal in small amounts, marshy areas
- Nightshades—gas colic, can be fatal
- Milkweed (narrow leaf species)—poisonous leaves, remains poisonous after dried, larger amounts, can be a problem in hay
- Death camas (white flower)—early shoots are the risk prior to other vegetation emerging
- Cockle bur—early leaves, liver toxicity
- Oak trees—leaves are toxic, especially in the spring, cause kidney failure
- Bindweed—colic from plant, seeds in hay can cause colic later on as well
- Locoweed—if neurologic, may not recover, unrideable
- Sage—similar to locoweed poisoning, remove from sage to recover
- Russian Knapweed—neurologic, starvation because of inability to chew, poor recovery
- Yellow Star Thistle—appetizing, neurologic, starvation because of inability to chew, irreversible
- Senecio and hounds tongue—photosensitization (liver damage), can be a problem in hay
- Clovers—photosensitization (liver damage), excessive bleeding, inability to clot
SELENIUM ACCUMULATORS
- Prince’s Plume
- Woody aster
- Two-grooved milk vetch
- Penstemon
- Gum weed
NITRATE ACCUMULATORS
- Kochia weed
- Sorghum grasses
- Jimsonweed
- Lambs quarters
OTHER NOXIOUS WEEDS AND PROBLEM PLANTS
- Leafy spurge
- Foxtails
- Cheatgrass
- Fescue (endophyte infected)
BHN: What are symptoms a horse would show if they had contact with or ingested a plant that is toxic?
Mastellar: Symptoms vary widely. Everything from an unsteady gait, dark urine, colic, to even death can be symptoms of poisonous plant ingestion. Acute laminitis can be caused by contact with black walnut shavings. Carefully observing your horse’s environment and feed can help you and your veterinarian narrow down the potential cause of your horse’s symptoms. Depending on the symptom(s) there may be differential diagnoses to rule out.
Kathy Whitman: Colic is a frequent sign, immediately recognized, and readily treatable; conversely, more serious cases of neurological signs, like with locoweed, may be more dangerous if not caught immediately and have a poorer prognosis. Adults may not always be affected, but congenital deformities in foals can occur, such as cases of endophyte-infected fescue grass consumption.
In situations where odd clinical signs, like excessive slobbering or discomfort in the mouth are evident, irritating plants should be considered. Feces that smell of sage is an obvioussign of sage brush consumption and potential toxicity, and horses should be removed from access immediately.
Exposure to selenium accumulating plants is not noticeable right away, but with ongoing consumption results in horizontal cracks in hooves, poor hair coat, broken hair in mane and tail. In some cases, death may be the only clinical sign seen. Veterinary assistance in the cases may be the only way to identify the causative plant, and even then can be challenging.
BHN: Do horses typically eat plants they shouldn’t or will they avoid them?
Whitman: Horses are more selective than say, cattle, so their risk is relatively low on well-managed pastures. The risk for toxic plant consumption increases as good quality forages are less available (overgrazed), pastures are over-stocked, or weather conditions, such as drought or even deep snow that only allows access to toxic plants growing above snow, such as sage.
In situations where movement to a brand new pasture is occurring, I recommend, for any grazer, that they not be released on the pasture when hungry. This reduces the chance of indiscriminate consumption, and horses especially will continue with their selective grazing habits.
BHN: What is the best way to remove these plants from your property?
Mastellar: Scouting and awareness are key. Management and control strategies vary depending on the species of plant. Sometimes promoting desired forage species (i.e., grasses and legumes) is enough to crowd out problematic plants. Exercise paddocks, and dry lots should be scouted often due to not having good forage cover to outcompete potentially harmful plants. Mowing before seed formation can help in some cases.
Effective control methods can be different depending on the season and where the plant is in its life cycle. Trees and shrubs can be removed manually and most will not regrow. Work with your local extension personnel to identify plants of concern and the best ways to eradicate them. Thoroughly read the labels on any herbicides used. Be sure to allow for any grazing restrictions and residual effects.
Walk pastures and fencelines regularly, particularly after storms. The branches and leaves of some tree species become sweet and poisonous when wilted. The risk of poisoning increases when a storm big enough to break branches or topple trees goes through.
Also be aware of what’s in your hay. Know what desirable species look like in your hay and purchase from a reputable seller. Weed seeds from contaminated hay can grow in pastures where it is fed. While looking for poisonous plants, also keep an eye out for injurious plants, such as burdock or foxtail and remove them at the same time.
Also be aware of what’s in your hay. Know what desirable species look like in your hay and purchase from a reputable seller. Weed seeds from contaminated hay can grow in pastures where it is fed. While looking for poisonous plants, also keep an eye out for injurious plants, such as burdock or foxtail and remove them at the same time.
BHN: Are there some plants that are fatal if ingested and some that just cause negative symptoms?
Whitman: Absolutely! Most toxic plants are dose-dependent, meaning that there is a threshold or tolerance for a certain level. Once the animal goes over that level, then it becomes a problem. In most cases, a mouthful of a toxic plant, or accidental ingestion isn’t an issue, or may only result in minor issues. In the case of something like water hemlock, however, it can be fatal very rapidly at small doses.
There are also instances where horses can develop some tolerance to what we would consider toxic plants. I’ve seen some horses have no problem with bindweed, but those same horses have access to other forages and have had time to adapt to bindweed as it’s grown. That said, we should never rely on a horse “adapting” to toxic plant exposure — again, they all have a toxic dose.
Identification of any toxic plants on your pasture is important for this very reason. If you see a few toxic plants that have a high tolerance level, then pasture management may be the only strategy required. On the other hand, if a low threshold toxic plant is identified, or a large number of any toxic plant that may be a risk, then other control strategies may need to be considered.
BHN: Can you treat horses that have ate or come into contact with a toxic plant? What does recovery look like?
Mastellar: Yes, contact your veterinarian. They are the best resource for treating a suspected poisoning and treatment will be different depending on the plant, amount consumed, and other factors. As you are reaching out to a veterinarian, remove the suspected source of poisoning to prevent the case from getting even worse. Quickly contacting a veterinarian can give you more options as there may be treatments to reduce absorption of toxins from material already ingested. Continue to work with your veterinarian on a recovery plan that considers the details of your horse’s particular case.
Whitman: If caught in the early stages, routine medical treatment can be effective. Horses that show colic signs can benefit from decontamination, or essentially flushing the gut, and fluid support. Removal from plant exposure is key. Some neurological effects may take longer to recover, and in the case of such plants like Russian Knapweed and Yellow Star Thistle, those signs may never resolve. Some plants like water hemlock are almost always fatal, so if you do find a deceased animal in your pasture, consultation with your veterinarian and performing a necropsy as soon as possible is important, particularly if other horses are on the same pasture. If acute plant toxicity is the cause of death, that plant material may be found in the digestive tract.
BHN: Any other recommendations regarding toxic plant consumption in horses?
Whitman: While we often want to blame unexplained illnesses on something like a toxic plant, it’s important to remember that plants toxicities cause things like colic, neurological signs, and sudden death, just like a lot of other diseases. The signs of toxic plants are not specific, so working with your veterinarian to determine causes of illness is important. Being able to identify toxic plants, particularly early in the growing season, is an important step in keeping your horses safe. I often use Google to snap a photo of a plant I’m unfamiliar with to get some idea of what it may be. And finally, never hesitate to reach out for help. There are local Extension and State specialists in your area that have expertise in local plants and can help you address issues as they arise.
Additional Resources:
CSU College of Veterinary Medicine and Biomedical Sciences Guide to Poisonous Plants
USDA ARS Poisonous Plants Research Laboratory
Diagnostic Laboratories Plants: CSU Plant Diagnostic Clinic ($25 per identification)
Diagnostic Laboratories Toxin screening: Cornell Veterinary Diagnostic Lab
The post Don’t Let Them Eat That: Toxic Plants appeared first on Barrel Horse News.
Read More...