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Horses are exposed to a number of potentially poisonous substances in their environment. Toxic chemicals are found in poisonous plants, insects, drugs and medications, insecticides, animal baits, and substances such as wood preservatives and paint.

These toxins can affect the central nervous system, the digestive and respiratory systems, and the organs of affected animals.

If poisoning is suspected, immediate action is necessary to prevent debilitating effects and possible death of the horse.

Since horses are unable to vomit, an alternate plan of action should be in place in case a horse ingests a toxic substance.


  • Lack of ability to perform
  • Tremors
  • Erratic behaviors
  • Lack of coordination
  • Convulsions
  • Aimless wandering or staggering
  • Difficulty in drinking and eating
  • Weight loss
  • Sleepiness
  • Discoloration of mucous membranes
  • Slowed heart rate and cardiac failure
  • Respiratory failure
  • Excessive salivation
  • Loss of ability to urinate normally
  • Colic
  • Depression
  • Reproductive problems


The potential list of poisons that may affect horses is long and includes many trees, plants, chemicals, medications and drugs, household and stable supplies, and insects.

Ingestion of poisonous plants or forage, contaminated roughage, and improperly stored grain and hay is the most common cause of poisoning of horses.

All of these items contain potentially deadly toxins that may affect the horse's central nervous, respiratory, circulatory, and digestive systems, and major organs by shutting them down, depressing them, or hindering their functions.

Some substances, such as animal baits, are attractive to horses, and, if left in accessible places, horses will readily eat them. Overdoses of drugs and medications can be deadly, and some horses have allergies that cause them to suffer anaphylactic shock when given a drug by injection.

Awareness of the dangers of poisoning and of toxins in the environment will help horse owners and handlers avoid putting horses in a situation where they might ingest poisonous plants or substances.


Persistent efforts to eliminate or control poisonous plants and trees in their environment, plus attention to good stable and horse management to make sure horses are not exposed to poisonous substances of any kind are the best methods of prevention.

Using resources such as local Extension Agents in each county will help in the identification and control methods of poisonous plants and trees unique to the local environment.

Keeping pastures and trail areas mowed and free of weeds that might include poisonous plants is important. Growing an assortment of healthy grasses in pasture areas will not only provide horses with good forage, but will help crowd out noxious plants.

Making sure that horses have good quality hay that is not contaminated with either insects or mold and fungi, and providing quality forage will help prevent horses from eating noxious weeds in the trail and pasture environments.

A healthy diet that provides all the nutrients the horse needs will prevent mineral and other deficiencies that sometimes drive horses to eat poisonous plants they might find along the trail or in the pasture.

Educating visitors and neighbors about the dangers of feeding horses grass clippings that may be contaminated with insecticides or poisonous ornamental plants will help minimize the risk of inadvertent poisoning by well-intentioned people.

Good stable management practices will ensure that harmful substances used in the area will be stored and used properly where horses cannot consume harmful animal baits, medications, and other supplies.


Call your veterinarian immediately if poisoning is suspected. Locate the source of the poison and make sure the horse or other animals do not have further access to the poisonous substance.

Treatment will depend on the type and amount of poison ingested, or contacted, if the poison is on the skin or the coat.

If the horse is down or having difficulty breathing, clear the airway.

Usually a veterinarian will do gastric lavage followed by an activated charcoal slurry given through a nasal tube. The slurry will absorb chemicals remaining in the horse's stomach and intestines.

In some cases, horse owners or handlers can begin this procedure before the veterinarian arrives if they are equipped to do so and know how to perform the procedure without injuring the horse.

Next, a laxative such as Epsom salt or sodium sulfate is given to further clear the digestive tract. In some cases, mineral oil may be used.

Large volumes of intravenous fluids are given in cases of acute poisoning. These fluids support circulation, treat shock, and protect the kidneys.

Horses may go into shock, coma, or convulsions when poisoned. In each case, a veterinarian should be prepared to act quickly with tracheal intubation, artificial ventilation, intravenous drugs, and other resources depending on the type of poison, how much was ingested or absorbed, and the physical condition of the horse.

If the horse has a poisonous substance on its skin or coat, the substance should be washed off with soap and a large amount of water. Mineral or vegetable oil may be used to remove oil, gasoline, or similar products. The oil should be followed by washing with water and a mild detergent.

Most products containing chemicals are labeled for identification. If the name of the product is known, but information on the composition and toxicity of the product are not available, the ASPCA Animal Poison Control Center at 888-426-4435 should be called, or call the emergency room of the local hospital and ask for information from the Poison Control Center.

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EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.