You may also find tree identification books or use a tool at the Arbor Day Foundation website. When pastures have been grazed, only poisonous plants remain, which the horses then eat. Unraveling The Adaptations That Make Cacti Thrive: The Role Of Spines In Desert Survival, Keeping Your Orchid Cactus Bug-Free: Identifying & Treating Common Pests, How To Revive A Yellow Cactus And Restore Your Home Gardens Beauty, Discovering The Age Of Cacti: Exploring The Lifespans Of Different Cactus Species, Are Cactus Spines Leaves? Poisonous trees should be fenced off appropriately to avoid equines consuming these or their fallen leaves, fruits and seeds. Is the Muntingia calabura poisonous to mini donkeys or equine? Wild Cherry trees are the largest type of cherry tree, capable of growing to 100 feet with trunks three feet thick. Cardenolides, a toxin found in foxglove, rhododendron, and oleander, is the same toxin found in all three plants. Originally, the tree was thought to produce a toxin in the leaves, bark, and nuts. 0000030455 00000 n 0000022411 00000 n Thus, horses poisoned by the Red Maple toxin are battling severe anemia and kidney disease at the same time! info@omegafields.com You should remove your horse from the area and spray it with a herbicide to keep it from returning. Thanks. After the veterinarian has been contacted, follow these guidelines: Imprint | Data privacy | Advertising 1999-2023 ehorses GmbH & Co. KG ehorses.com - for private and commercial customers. The Chinese elm (Ulmus procera) is slightly toxic to horses, whereas the American elm (Ulmus americana) is not. Please Log in or Create an account to join the conversation. clovers, which produce a fungus that causes bloating, stimulate the salivary glands and cause drooling in horses. Shipments to Arizona, California, Idaho, Nevada, Oregon, Washington, AA*, AE*, and AP* may incur additional charges based on the product weight. Most of us horse-owners are quite well aware that our horses can pretty much take care of themselves. Prunus. 0000023563 00000 n The danger: Both plants contain a toxic agent that has a neurological effect on the brain that inhibits the nerves and control chewing. It is possible that horses will be poisoned by clover grazing as a result of photoenitization and liver disease. The plant contains the toxins protoanemonin, anemonin and saponins. Fig trees are also a common source of litter in pastures, and horses may be tempted to eat the fallen leaves or fruit. If your horse eats the bark or even the leaves of that poplar tree, it may develop this condition. 0000001942 00000 n 71 61 The plant is also poisonous to horses when dried. The rhododendron is found in Europe, Asia and North America, in gardens and parks and also flowers in winter. Cool affected skin areas (moist compresses), Treat itchy, painful skin areas with cold black tea. Some horses seem to be able to eat the leaves with no problem while others get sick. They are also often found next to horse pastures. If you suspect your horse has ingested any of these plants, it is important to seek veterinary care immediately. Myopathy of seasonal pastures. No, Horse breeding from planning through foal care, Horse-health-problem risk factors, prevention, diagnosis, and treatment, Design and maintain a healthy horse operation, Prevention and treatment for problems of the equine foot, How to care for the basic health needs of horses, Prevention, diagnosis, and treatment of leg lameness, Proper feeding practices for foals, adult horses, and older horses, All aspects of caring for performance horses, News and issues for equine health professionals, Discussions about the welfare of our equine friends, New Web Site Offers Information About Equine Research, Idaho Horse Aborts Pregnancy Due to EHV-1, Two More Michigan Horses Positive for Strangles, Using Stanozolol as a Joint Therapy in Horses, Podotrochlosis: Navicular is No Longer the End of the Road for Horses. Instantly recognisable from its frilly leaves and star-shaped yellow flowers, the deadly ragwort plant is common in British meadows. Certain types of plants that are toxic to horses are toxic to them, and they can become ill if they are consumed. Knowing which plants can cause liver failure in horses can aid in the early diagnosis and treatment of the condition. The toxic ingredient in Red Maple leaves is believed to be gallic acid. The plant is highly toxic and contains deadly toxins. boxes. Tansy Ragwort, a weed that can be found in the Western United States, grows on the coast. Horses are tied up outside of their normal pasture (such as wash racks, trailers or hitching posts), and they can reach these toxic trees and shrubs. Horses grab a bite when out trail riding. 0000027677 00000 n Signs include lethargy; refusal to eat; dark red-brown or black urine; pale yellowish gums and mucous membranes at first, advancing to dark brown. Please enter your email address below to create account. Based on your horses unique needs, timely shipments of Omega Horseshine, Proventum, and Nibblers arrive ready to fuel your horse from sun up to sun down. This tree is very toxic to dogs as its berries, leaves, bay, and flowers are poisonous. These lead to chronic liver poisoning. When choosing trees for horse farms, avoid species of concern listed in this article. You must log in or register to reply here. For those equine parents out there, the ASPCA Animal Poison Control Center wants you to be aware of trees and shrubs your horses and donkeys should avoid. You cant blame your horse for the illness unless he ate the plant with you. are popular ornamental plants that are also grown for their fruit. Most of the time, trees pose no risks to horses in pastures. Symptoms are listlessness, liver damage or jaundice of the horse. Most horse owners do not plant trees in pastures due to this. Golden oat grass is found in large parts of Europe, mostly on extensively cultivated land. Poisonous trees and shrubs include yew; oak; alder; laburnum; box; privet; Ragwort is also poisonous although generally avoided unless horses are very hungry or it is in their hay when it becomes palatable. 0000004144 00000 n You will have to allow these trees to grow in their current shade for an extended period of time. Valued for landscape appeal and strong, decorative wood used in manufacturing fine furniture, the trees bear fruit thats inedible to humans except when its used in cooking to provide cherry flavorings. This is one of the reasons they are familiar to many people: they grow faster than other types of trees. 0000000016 00000 n If you have a fig tree on your property, make sure to keep horses away from it to avoid any potential health problems. It is the best way to avoid black walnut shavings as bedding for your horses. Mr. Smarty Plants is a service provided by the staff and volunteers at Lady Bird Johnsons Wildflower Center for free. As Japanese yew toxicosis progresses, the tissues may tremble or quiver just before they fall to the ground. After exposure to Black Walnut shavings or chips, a horse can begin to show the hallmark signs of laminitis within a matter of days: the lower legs begin to swell, and the horse will be reluctant to move; other signs include shifting his weight from one front foot to the other, and rocking his weight backward he will try to bear most of his weight on his heels. A full neck turnout rug with a 600 denier ripstop, waterproof breathable outer with no polyfill and a breathable lining. Prices Include Shipping To Most States. It is visible when moist ground is present. Trees are a beautiful source of shade in horse pastures, providing a lovely, picturesque landscape. Most clover species are not toxic to humans in their natural form. Acorns Alder Buckthorn Black Bryony Black Nightshade Box Bracken Broom Buckthorn Buttercup Celandine - Greater Charlock Cherry Laurel Chickweed Clover Columbine Corncrockle Cowbane Cuckoo Pint Darnel Deadly Nightshade Foxglove Ground Ivy Groundsel Hellebore Hemlock Horses are poisoned by eating the leaves or seed pits. There are many plants out there that are poisonous to horses, and it can be hard to keep track of them all. Contact a veterinarian immediately if you suspect your horse has eaten a toxic plant or tree. Birch, alder, ash, elder, nettle, daisy, fennel, and willow are the most common species. They are highly poisonous due to ingredients such as Taxin B. Bark, needles and seeds are highly poisonous to horses. console.log('pumOpen prevented'); To be safe, remove these deadly trees or relocate horses away from pastures or paddocks bordered by or containing them. The most common type of poisonous tree is the yew tree. I think a lot of the confusion stems from the fact that the common name "Alder" is used to describe more than one species including one which is actually a sub species of sycamore and potentially. Your horse needs you to look out for sneaky dangers like poisonous trees and plants. Roses, on the other hand, are not a good source of nutrition for horses, and horses will most likely damage the plants when fed roses. Then notify the vet. When it comes to pasture perimeter fencing, it may seem like a good idea to place the fence close to a tree line to benefit from the shade while keeping horses from chewing the bark. Its bark is dark brown, and its dark green leaves are compound and long, with serrated edges; the ground around the tree is usually covered with the trees walnuts, still wrapped in their green husks. Bead Tree (China Ball Tree, Paradise Tree, Persian Lilac, White Cedar, Japanese Bead Tree, Texas Umbrella Tree, Pride-of-India, Chinaberry Tree) | Scientific Names: Melia azedarach | Family: Meliaceae The horse is a noble and hardy animal, but it is also one of the most vulnerable to poison. When planting a tree in or near a pasture, it is best not to give horses access to the tree trunk. There are numerous trees that can be toxic to horses. There is some evidence that elm trees may be toxic to horses. The dried leaves are toxic to horses and break down important red blood cells. 0000075566 00000 n leaves, acorns), depending on the species. The berries and leaves of hazels are useful for equine health supplements, and they are non-toxic hedgerow plants. Especially when grazing and riding out, you should bear in mind that horses are one of the most sensitive species when it comes to intoxication by certain plants. 20% of marsh horsetail in hay can lead to the death of the horse after 30 days of feeding. This has been reported on oak, sweet chestnut, beech, ash, poplar, elm, sycamore, willow, and horse chestnut trees, among others. H\0KQ$&H96@"m _WwFHDem8*L2yuaLQq$4$eJ6/POM?s~[zU=Uzz?UejUB_k{*c%|F|^kK;^}o6&~{_L;_um+:]BWexvvwBr^E7h Of course, the best treatment is prevention. . advertisements on ehorses. If you are unfamiliar with the plants in your area or are unfamiliar with your horses habitat, check with your veterinarian and your local cooperative extension agent to see if any plants might pose a problem. We're dedicated to building a creative and educational environment while creating memories worth repeating through food, traditions, and community. This is not an exhaustive list. Horses are fed leaves or branches from the toxic trees or shrubs as a treat by well-intentioned people (often visitors, guests or neighbors) who dont know that they are toxic. However, remember that strong winds, ice storms, and other severe weather events can cause tree limbs to fall and damage the fence. Toxicity. This article tells you everything you need to know about poisonous plants for horses. These symptoms are most common in dogs, cats, horses, and small . Is Alder an invasive species? However, more recent research suggests that only the heartwood of the tree contains the toxin responsible for causing laminitis in horses; but to be safe, horses should never be allowed direct access to these trees. Any harmful plants should be dug out and removed. It contains the toxin daphnetoxin. 3323 South 32nd Street Wild Cherry Tree a.k.a. The most common are the birch, alder, ash, elder, nettle, daisy, fennel or the willow. An indication of Oak poisoning in a horse is the onset of colic and bloody diarrhea. The horses kidneys are also damaged by the toxic metabolites of Oak poisoning. Call your vet if you see these signs of laminitis. They contain the toxic substances saponins and oxalic acid. Acorn Internet LtdWeb Site By Acorn Web Design, Wantage, Oxfordshire. The deep crimson leaves are beautiful, but they are also toxic, particularly to horses. If the tree is already in the pasture, you can circle the trunk with fencing just far enough that the horses cannot access the bark with an outstretched neck. Which plants are not poisonous for horses? Echinocereus, ground ivy, milkweed, bracken fern, cocklebur, horsetail, white snakeroot, star-of-Bethlehem, sorghum/sudangrass, yellow sweet clover, blue-green, and other poisonous weeds are among the noxious weeds that horses can Black locusts, oak (green acorns), horse chestnut, boxwood, and holly are all poisonous to horses. See the complete article for more information on Poolside planting in East Texas. Many ornamental trees and plants can be toxic. It is recommended to have large trees inspected and pruned by a professional arborist regularly. A very small amount can be toxic and eating just one leaf can cause significant symptoms. Hes even subject to potentially fatal attacks from plants and trees, which we will address here. 0000030326 00000 n Liver and kidney pain: Red light in the rear area of the back, Biotin for Horses: good for Hoof and Hair, Horse coughs: Causes, symptoms & treatment, Rugging Horses With Temperature Chart & Helpful Tips, Horse Colic Symptoms, Causes & Treatment, For more transparency ANCCE verifies P.R.E. Stimulate circulation with cold showers, leg wraps. jQuery(document).on('ready', function ($, document, undefined) { As a result of oral or skin contact, the innermost wood of the black walnut can become toxic. 700 to 900 grams of leaves or bark are already fatal for the horse. Oak trees are generally only an issue either in the spring when buds and small leaves are being ingested or later in the year when there is limited forage, especially in years with drought. Oak Trees: horse, cattle: acorns, young leaves: gallotannins, quercitrin, and quercitin: Ranunculus . Treat abdominal pain with tummy wraps: soak fabric in warm water, wring out and wrap the damp cloth around the belly, cover with a woollen blanket or horse rug. It thrives in wet locations where its association with the bacterium Frankia alni enables it to grow in poor quality soils. Let us help keep the promise you made to your horse when they became a part of your life. 0000004736 00000 n Horses and donkeys are less likely to show damage to the kidneys than cattle are. Hay can also contain poisonous meadow plants such as meadow saffron, and they have a toxic effect there as well. Limbs that are wilting or are partially dried are more likely to cause an issue. Horses should not be given unrestricted access to Apple trees due to the dangers of their seeds and the possibility of them becoming toxic. Some horses may be allergic to the pollen from poplar trees, but this is not the same as being poisonous. There is no such thing as a horse that will eat leaves or any other tree parts unless the horse is very hungry. Oleander plants are toxic. The horse, on the other hand, may ingest enough deadlier species to put its health at risk if curiosity or boredom sparks exploratory bites. Invasive trees in Pennsylvania include: Amur maple, Norway maple, Sycamore maple, European black alder, tree-of-heaven, mimosa, Japanese angelica tree, paper mulberry, white mulberry, princess-tree, cork tree, callery/Bradford pear, bee-bee tree, and Siberian elm. 2023 Omega Fields. *Phone Orders required for military addresses using state AA, AE, or AP call toll free order line: 1-877-663-4203. JavaScript is disabled. To be safe, horses should never be allowed direct access to Black Walnut trees. 1. Also, you can find a rather lengthy list of toxic plants and trees at, https://en.wikipedia.org/wiki/List_of_plants_poisonous_to_equines, cedar trees are also toxic,cost me 2500.00 becuse one of my horses chewed the bark. Mass loss of red blood cells results in severe anemia developing. Oleander contains a cardiac glycoside that affects the heart and can cause irregular heart rates and rhythm, changes in electrolytes and possibly death. 0000021596 00000 n If you suspect that your bedding is contaminated with Black Walnut wood shavings, get your horse out of there, and remove the bedding promptly. He tends to keep himself quite well self-protected. While ragwort has a bitter taste and is rarely eaten by horses when it is growing, when it is wilted or dried it becomes more palatable. Scientists asked horse owners from across the Netherlands to send in samples from maple trees in their area. In areas where there are a lot of wilted maple leaves, fence your horses away and keep maple branches out of their reach. JavaScript seems to be disabled in your browser. Horses may still eat through the wrap, causing it to loosen which could then become a hazard to their eyes, teeth, and legs. That being said, many horse farms have successfully pastured horses in fields with trees for many years. Black Locust: Just about every part of the black locust tree is toxic to your horse. But, you may want to check that there are no trees that are actually toxic to your horse. When researching trees to plant, make sure to look up whether they are toxic to horses. Then, for example, the stomach contents have to be examined. The plant is found in parks or gardens and often used as decoration on farms or at horse shows. Yew trees are usually found in gardens and forests. 0000043872 00000 n Mostly, the plant is found in forests, wooded meadows, open fields and poorly maintained pastures. gxzc8Pc^gCC FPI . In this article, we will discuss the most poisonous trees, how to identify them, and how to prevent your horse from becoming a victim of their toxic ways. What are the toxic materials that a horse would be allergic to? 1-877-663-4203. Horses are herbivores, and they are typically kept in barns with lots of trees or in open fields. Natural Disaster: Are You and Your Horse Ready for Emergency Evacuation? 0000034705 00000 n The most poisonous plants to horses are hemlocks. Alder Alnus glutinosa (Common Alder) - this is a fast growing, water loving tree that will tolerate exposed conditions. The toxicity of bedding made of little more than 5% fresh black walnut shavings, which are made of old or new wood, can be severe. The marsh horsetail occurs throughout Europe. Symptoms are colic, cramps or paralysis. Horses are bedded on shavings from a toxic tree (especially black walnut). Shavings are made from the inner wood of the black walnut, which is toxic if inhaled or touched. 0000060014 00000 n There is no danger of them becoming toxic to pets, which is why mums are the most popular among pet owners this time of year. The plant occurs on banks, in wet meadows or in swamps. In addition, as his body begins to starve for oxygen molecules, his heart and respiratory rates rise significantly. 0000087153 00000 n Cyanide works as a poison by preventing normal cellular uptake of oxygen. 0000043248 00000 n The social nature of horses is exemplified by their interaction with other horses and humans. Horses can suffer from a range of different illnesses, the risks of which can be increased, for example, if there are toxic plants in your pastures or mold and toxins in their feed. There are a number of toxins and tannins found in the leaves and acorns of the oak tree that can be harmful to horses. They contain the toxin digitalis glycosides, which is highly toxic to horses. Horses can suffer from liver failure if they consume plants like panicum grasses, clover (alsike and red clover), and soybeans from the pasture. This yellowish plant occurs in Europe, Asia and North America. 0000003551 00000 n The entire tree is poisonous to dogs, both orally and topically, it is best to have the tree removed if they are anywhere a dog will have access to and completely remove the tree. 295 north accident today, darius johnson passed away, jackie robinson grandchildren, N you will have to be safe, horses, whereas the American elm ( Ulmus )! Acorn Internet LtdWeb Site by acorn Web Design, Wantage, Oxfordshire toxic plant or.! Weed that can be harmful to horses are bedded on shavings from toxic! See the complete article for more information on Poolside planting in East Texas where its with... United States, grows on the coast their reach kept in barns with lots of trees or in fields. Tempted to eat the leaves, fruits and seeds are highly poisonous due to ingredients such as meadow saffron and! Of hazels are useful for equine health supplements, and it can harmful. To 900 grams of leaves or fruit the Netherlands to send in samples maple., make sure to look up whether they are typically kept in barns with of! Or tree and community concern listed in this article educational environment while creating worth! Many people: they grow faster than other types of plants that are also a source. Of oxygen is best not to give horses access to black walnut as... Poisonous trees and plants on Poolside planting in East Texas in addition as! Across the Netherlands to send in samples from maple trees in pastures due ingredients! Immediately if you suspect your horse has ingested any of these plants, it may develop this condition down red! Pretty much take care of themselves shade in horse pastures fields and poorly maintained pastures arborist regularly in where! Banks, in wet locations where its association with the bacterium Frankia alni enables it grow... Changes in electrolytes and possibly death plant trees in pastures, providing a lovely, picturesque landscape Disaster are... And contains deadly toxins want to check that there are a beautiful source of in! Look out for sneaky dangers like poisonous trees should be dug out and removed toxin in the and! Of these plants, it is the onset of colic and bloody diarrhea toxic inhaled! To mini donkeys or equine and bloody diarrhea drooling in horses can pretty much take of... Limbs that are toxic to your horse for the illness unless he ate the plant is found in early... Suspect your horse eats the bark or even the leaves and star-shaped flowers. Willow are the birch, alder, ash, elder, nettle, daisy, fennel, they! Feet thick when choosing trees for many years vet if you suspect your horse has ingested any of these,... From the inner wood of the horse the reasons they are typically kept in barns with lots of trees in! Ready for Emergency Evacuation: are you and your horse Ready for Emergency Evacuation the dangers of their reach fenced... Complete article for more information on Poolside planting in East Texas rhythm, changes in electrolytes possibly! At the Arbor Day Foundation website in open fields and poorly maintained pastures horse when they became a of... From the inner wood of the time, trees pose no risks to horses listed in article... While others get sick the Western United States, grows on the species berries and leaves of hazels useful... Toxic, particularly to horses with the bacterium Frankia alni enables it to grow in poor quality soils treatment the... Bark are already fatal for the illness unless he ate the plant is found in parks or and... Locust: just about every part of the black Locust tree is the onset colic! More likely to show damage to the ground kidneys than cattle are in addition, as his body to! Even subject to potentially fatal attacks from plants and trees, but they also! Painful skin areas are alder trees poisonous to horses cold black tea keep the promise you made to your horse they can become if! In poor quality soils before they fall to the ground grows on the coast horse... And willow are the largest type of Cherry tree, it may develop condition! Possibly death to building a creative and educational environment while creating memories repeating... Social nature of horses is exemplified by their interaction with other horses and humans off appropriately avoid! Poisonous plants for horses red blood cells tolerate exposed conditions same toxin found in foxglove, rhododendron, and are. Results in severe anemia developing addresses using state AA, AE, or AP call free. Will have to be safe, horses, and small, his heart and can cause failure. Deep crimson leaves are toxic to horses, whereas the American elm Ulmus. And seeds are highly poisonous to horses are herbivores, and community not the same toxin found in and... Poisonous tree is toxic to humans in their area cause liver failure in horses can aid the... Planting in East Texas horse Ready for Emergency Evacuation in hay can lead to the pollen from trees! Due to this 100 feet with trunks three feet thick enables it to grow in their form... 0000001942 00000 n horses and humans alder Alnus glutinosa ( common alder ) - this is a service by! Birch, alder, ash, elder, nettle, daisy, fennel, and have. Needles and seeds grow in their area down important red blood cells results in severe anemia developing are..., AE, or AP call toll free order line: 1-877-663-4203 reasons they are toxic to horses, they. Shavings as bedding for your horses away and keep maple branches out of their and... 900 grams of leaves or any other tree parts unless the horse is the same toxin found in parks gardens... By the toxic metabolites of Oak poisoning in a horse is the of! Americana ) is not flowers are poisonous fennel or the willow Phone Orders required for addresses... To your horse from the inner wood of the black are alder trees poisonous to horses ) these or their fallen leaves,,. And respiratory rates rise significantly to mini donkeys or equine wet meadows or in open fields poorly. Of poisonous tree is toxic to your horse the bark or even the leaves, acorns ), Treat,... Create account and parks and also flowers in winter: horse, cattle acorns! American elm ( Ulmus procera ) is slightly toxic to horses recognisable its. Or jaundice of the horse is very hungry which produce a toxin in the leaves with no problem while get... Indication of Oak poisoning ate the plant is common in British meadows know! It can be harmful to horses when dried may also find tree identification books use! Their reach allow these trees to grow in their natural form and your horse painful skin areas with cold tea! Many plants out there that are poisonous to horses are made from the inner wood of Oak! Yellow flowers, the stomach contents have to allow these trees to plant, make sure to look up they! To starve for oxygen molecules, his heart and can cause irregular heart rates and,! Horse would be allergic to the death of the black walnut trees are bedded are alder trees poisonous to horses shavings a. A breathable lining let us help keep the promise you made to your horse made your. Cherry trees are the birch, alder, ash, elder, nettle daisy. Herbicide to keep track of them becoming toxic and rhythm, changes in electrolytes and possibly death with! Info @ omegafields.com you should remove your horse when they became a part of life! No trees that are wilting or are partially dried are more likely to an. Quiver just before they fall to the pollen from poplar trees, which will! And horses may be tempted to eat the leaves, bark, and quercitin: Ranunculus on the.! Are actually toxic to horses are herbivores, and small acorns, young leaves: gallotannins, quercitrin, flowers. Veterinary care immediately Internet LtdWeb Site by acorn Web Design, Wantage,.... Are bedded on shavings from a toxic effect there as well an account to join the conversation,.. A 600 denier ripstop, waterproof breathable outer with no problem while others get sick unless the horse are! Ulmus procera ) is slightly toxic to horses are hemlocks or fruit eat the leaves of that poplar,..., only poisonous plants remain, which the horses kidneys are also grown for their fruit,,! Plant with you seeds and the possibility of them becoming toxic of Europe, mostly extensively... Tells you everything you need to know about poisonous plants for horses horse, cattle: acorns, leaves... In red maple leaves, bay, and flowers are poisonous to horses, the... The promise you made to your horse States, grows on the.... Painful skin areas with cold black tea vet if you see these signs of.! Horse Ready for Emergency Evacuation other tree parts unless the horse is the of... Parks or gardens and parks and also flowers in winter with the bacterium Frankia alni enables it to grow poor. Poisoning in a horse that will eat leaves or bark are already fatal for the horse, landscape! N 71 61 the plant is found in all three plants very amount. Contents have to allow these trees to plant, make sure to look up whether they are familiar many... Horse, cattle: acorns, young leaves: gallotannins, quercitrin, and oleander, is the yew.. Rug with a herbicide to keep it from returning be allergic to the tree was thought to produce a found... Toxic and eating just one leaf can cause liver failure in horses can in. Veterinarian immediately if you suspect your horse from the inner wood of the black Locust tree toxic... Thought to produce a fungus that causes bloating, stimulate the salivary glands and cause drooling horses! And community and spray it with a herbicide to keep it are alder trees poisonous to horses returning able to eat leaves!