# Can Horses and Rabbits Eat Yarrow? Safety and Risks Can horses eat yarrow? In small amounts, yes. Yarrow (Achillea millefolium) is not a highly toxic plant for horses, and horses will often nibble a few stems in a pasture without any problem. The risk comes from eating a large quantity, from concentrated products like essential oils, and from yarrow that has been sprayed or grown near toxic weeds. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - A few yarrow plants in a pasture are generally not a danger to a healthy adult horse. The plant has mild toxic potential, not high toxicity, and problems usually follow heavy or repeated consumption. - Yarrow contains volatile oils and other plant compounds that can irritate the mouth, stomach, and skin, and in large doses can affect the nervous system. - Horses are often willing to eat yarrow. In a feeding trial, common yarrow added to oats did not stop horses from eating, and only the odor of dry common sage slowed intake [1]. - Rabbits, guinea pigs, and other small pets should not be given yarrow as a regular food. Their small body size means even a modest amount is a large dose relative to their weight. - If your horse ate a lot of yarrow, or if you see drooling, colic signs, wobbliness, or a rash, call your veterinarian. You can also call the ASPCA Animal Poison Control Center at (888) 426-4435 or Pet Poison Helpline at (855) 764-7661. ## Is Yarrow Toxic to Horses? Yarrow sits in a middle zone. It is not on the short list of plants that reliably kill livestock, and it is not a safe forage crop either. It is a common pasture and garden plant with mild toxic potential when eaten in quantity. Most cases involve horses on overgrazed pasture or in dry lots where yarrow is one of the few green plants left. Boredom, hunger, and a lack of other forage push horses to eat more of it than they normally would. Plant poisoning often depends on factors like the part of the plant eaten, the amount consumed, hunger, thirst, and how long the animal has been eating it [2]. Those factors matter here. A horse that nibbles two plants while walking a fence line is in a very different situation from a horse that has been eating yarrow for a week because the pasture is bare. ### Which Parts and Products Matter The whole plant contains the compounds of concern, but the flowering tops and leaves carry the highest concentration of volatile oils. Fresh yarrow is more aromatic and more likely to cause mouth irritation than dried hay. Dried yarrow in hay is usually a minor concern because the amount is small and mixed with other forage. Concentrated products are the bigger issue. Yarrow essential oil, tinctures, and herbal blends sold for horses can deliver a much larger dose of active compounds than the plant itself. Never add a yarrow product to feed or water unless your veterinarian has specifically recommended it and calculated the amount. ### Is Yarrow Toxic to Horses When It Grows in the Pasture? A pasture with scattered yarrow is not automatically unsafe. Many horses graze around it and ignore it. The practical rule is to watch the ratio. If yarrow is a small part of a diverse, well-managed pasture, the risk is low. If yarrow is taking over, or if your horse has little else to eat, the risk rises and you should manage the plant. ## The Toxic Principle and What It Does in the Body Yarrow contains volatile oils, including compounds in the same family as those found in other aromatic herbs, plus bitter sesquiterpene lactones. These are the same types of compounds that give yarrow its strong smell and its traditional medicinal use. In the body, these oils act as local irritants first. They can sting the lips, tongue, and gums, cause drooling, and upset the stomach. When a large amount is absorbed, the effects can extend to the nervous system and cause depression, unsteadiness, or sensitivity to light and touch. Some horses develop skin reactions after contact with the plant, especially on light-colored or thinly haired areas. Yarrow also has documented antiparasitic activity. Aqueous extracts of yarrow flowers showed strong activity against strongyle eggs and larvae in laboratory testing [3]. That finding is interesting for future deworming research, but it does not mean you should feed yarrow to your horse to treat parasites. The concentration used in that laboratory work is not the same as a horse grazing a pasture, and no dose for live horses has been established. ## Signs of Yarrow Poisoning in Horses Signs usually track with how much was eaten. Mild exposure causes mild signs. ### Early and Mild Signs - Drooling or lip smacking - Mouth or tongue irritation - Reduced appetite - Mild colic signs such as pawing, looking at the flank, or lying down more than usual - Skin redness, itching, or a rash on the muzzle, lips, or white markings ### Signs That Need Prompt Attention - Repeated or severe colic signs - Diarrhea - Depression or a dull attitude - Wobbliness, stumbling, or a wide-based stance - Sensitivity to light or touch - Muscle twitching - Difficulty swallowing ### Typical Timeline Signs from plant irritation often appear within a few hours of eating. Nervous system signs from a large dose tend to show up within hours to a day. Skin reactions can take one to several days to develop because they build with repeated contact. If your horse ate yarrow and looks normal 12 to 24 hours later, the risk of a serious problem is much lower, but keep watching for another day. ## What to Do Right Now 1. Move your horse off the pasture or away from the yarrow source. Offer clean water and a small amount of familiar hay. 2. Check the mouth, lips, and gums for redness, swelling, or plant material stuck in the cheeks. 3. Take a photo of the plant and note roughly how much your horse may have eaten. 4. Call your veterinarian if your horse ate a large amount, is showing any sign listed above, or has a history of colic or liver problems. 5. Call the ASPCA Animal Poison Control Center at (888) 426-4435 or Pet Poison Helpline at (855) 764-7661 for guidance, especially after hours. 6. Do not induce vomiting. Horses cannot vomit, and forcing anything by mouth can cause choking or aspiration. 7. Do not give home remedies, oils, or charcoal unless a veterinarian tells you to. If your horse is down, rolling violently, sweating, or unable to stand, treat it as an emergency and call your veterinarian immediately. ## How Veterinarians Treat Yarrow Exposure Treatment depends on the signs. For mild mouth irritation, a veterinarian may flush the mouth and provide soft, bland forage for a day. For stomach upset, treatment focuses on fluids, pain control, and protecting the gut lining. A veterinarian calculates any drug dose from your horse's weight and current health, so never use a dose from the internet or from a product label written for another species. For horses with nervous system signs, treatment is supportive. That can include intravenous fluids, sedation if needed, and monitoring for colic or dehydration. Blood work may be checked to look at liver and kidney values and electrolyte balance. If a large amount was eaten very recently, a veterinarian may give activated charcoal by stomach tube, but only under direct veterinary supervision. Skin reactions are managed by washing the area with plain water, keeping the horse out of the sun if the skin is burned or raw, and using medications your veterinarian prescribes. ## Outlook After Yarrow Exposure The outlook is good for most horses that eat a small amount. Mild mouth and stomach irritation usually resolves within a day or two with supportive care. Horses with a large exposure and nervous system signs need closer monitoring, and recovery depends on how quickly treatment starts and how much was eaten. Horses with liver disease, kidney disease, or a history of colic are more fragile and should be seen by a veterinarian even after a modest exposure. ## Prevention and Safer Alternatives Walk your pastures in spring and summer and identify what is growing. Yarrow has finely divided, fern-like leaves and flat clusters of small white or pale pink flowers. If you are not sure what a plant is, ask your veterinarian or a local extension office before assuming it is safe. Manage overgrazing. Hungry horses eat plants they would otherwise avoid, and hunger is a recognized factor in plant poisoning [2]. Keep pasture grass healthy, provide hay when grass is short, and rotate paddocks so horses always have something palatable to eat. Pull or mow yarrow in heavy concentrations, especially along fence lines and around gates where horses linger. Do not compost sprayed plants where horses can reach them. Be careful with herbal products. Aromatic herbs and their oils are used in animal feed as sensory additives, and safety limits are set by species and by product. For thyme oil, the safe level in complete feed for horses was set at 100 mg/kg, while the level for rabbits was 76 mg/kg and for cats 38 mg/kg [4]. Those numbers apply to a specific commercial additive, not to yarrow, but they show how much species and product matter. Never assume a plant product is safe because it is natural. If you keep rabbits or guinea pigs, offer a proper diet built on hay, fresh greens, and a measured portion of pellets. A good starting point is our guide to a [suitable diet for a rabbit](/knowledge/veterinary-medicine/nutrition/suitable-diet-for-a-rabbit). For a full list of plants and household items to avoid, see [rabbit safety: toxic foods and household hazards](/knowledge/veterinary-medicine/small-mammal-care/rabbit-safety-toxic-foods-and-household-hazards). ## Can Rabbits, Guinea Pigs, and Other Pets Eat Yarrow? Rabbits should not eat yarrow. It is not a recognized safe food for them, and its volatile oils can irritate the gut. Rabbits have a delicate digestive system, and any new plant can trigger loose stool or stasis. Do not offer yarrow as a treat, and keep wild yarrow out of reach if your rabbit has outdoor time. Guinea pigs should not eat yarrow either. The same concerns apply, and guinea pigs are even smaller, so a small amount of plant material is a larger dose relative to body weight. Do not assume that because a horse can nibble yarrow, a rabbit or guinea pig can too. Body size, digestive anatomy, and how the liver processes plant compounds differ a lot between species. If your rabbit or guinea pig ate yarrow, call your veterinarian or a poison control line and watch for drooling, refusal to eat, or changes in droppings. ## Limitations and When to Contact a Veterinarian This article cannot tell you whether your specific horse ate a dangerous amount. Plant poisoning diagnosis depends on the plant, the amount, the horse's health, and the timeline, and it often requires a veterinarian to sort out [2]. Individual cases need a veterinarian. Call your veterinarian the same day if your horse: - Ate a large amount of yarrow or had access to it for several days - Is drooling, off feed, or showing mild colic signs - Has a new rash or raw skin on the muzzle or white markings - Has a known liver, kidney, or colic history Call now, as an emergency, if your horse: - Is rolling, sweating, or unable to stand - Has severe or unrelenting colic signs - Is stumbling, weak, or having trouble swallowing - Is breathing hard or showing muscle twitching Schedule a routine visit if your horse had a mild exposure and recovered, but you want the pasture checked or you want help with a weed management plan. ## Frequently Asked Questions ### Can horses eat yarrow every day? No. Yarrow is not a forage crop and should not be a daily part of the diet. Occasional nibbling in a diverse pasture is usually harmless, but daily, repeated intake raises the chance of cumulative irritation and other problems. ### Do rabbits eat yarrow in the wild? Wild rabbits may sample many plants, but that does not make yarrow a safe food for a pet rabbit. Pet rabbits depend on you for a balanced diet, and yarrow is not part of it. ### Is dried yarrow in hay a problem for horses? Usually not. Small amounts of dried yarrow mixed into hay are unlikely to cause signs because the dose is low and spread out. If your hay is heavily contaminated with yarrow or other weeds, ask your veterinarian to review it. ### Can yarrow be used to deworm horses? No. Yarrow extracts have shown antiparasitic activity in laboratory testing, but there is no established dose or product for live horses. Use deworming products your veterinarian recommends and base the schedule on your horse's risk. ### What plants are safer to offer instead? Plain grass hay, quality pasture grass, and a balanced commercial feed are the safest foundation. If you want to offer herbs, ask your veterinarian first, and keep the amount small. ## Related Articles - [Can Horses and Rabbits Eat Vetch? Hairy Vetch Safety](/knowledge/veterinary-medicine/equine-care/vetch-safety-horses-rabbits) - [Can Horses and Rabbits Eat Queen Anne's Lace? Safety](/knowledge/veterinary-medicine/equine-care/queen-annes-lace-horses-rabbits) - [What Do Horses Eat? A Practical Feeding Guide](/knowledge/veterinary-medicine/equine-care/what-do-horses-eat-feeding-guide) ## References 1. [Horses' Response to a Novel Diet: Different Herbs Added to Dry, Wet or Wet-Sweetened Oats](https://pubmed.ncbi.nlm.nih.gov/35681799/). Animals : an open access journal from MDPI, 2022. 2. [Toxic plants affecting livestock in South America: Review of epidemiology, diagnosis, control, economic impact and implications to human health](https://pubmed.ncbi.nlm.nih.gov/41565163/). Toxicon : official journal of the International Society on Toxinology, 2026. 3. [In vitro anthelmintic activity assessment of six medicinal plant aqueous extracts against donkey strongyles](https://pubmed.ncbi.nlm.nih.gov/32430089/). Journal of helminthology, 2020. 4. [Safety and efficacy of a feed additive consisting of an essential oil obtained from the flowering aerial parts of Thymus vulgaris L. and/or Thymus zygis L. (thyme oil) for use in all animal species (FEFANA asbl)](https://pubmed.ncbi.nlm.nih.gov/41425764/). EFSA journal. European Food Safety Authority, 2025. ## Further Reading - [ASPCA Animal Poison Control Center](https://www.aspca.org/pet-care/animal-poison-control) - [ASPCA: People Foods to Avoid Feeding Your Pets](https://www.aspca.org/pet-care/aspca-poison-control/people-foods-avoid-feeding-your-pets) - [Merck Veterinary Manual: Horse Owners](https://www.merckvetmanual.com/horse-owners)