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What is Angel's Trumpet Poisoning?

Originating from South America, angel’s trumpets can be divided into 5 species and several hybrid varieties, and are often used as garden ornamentals. These evergreen trees or shrubs can grow up to 16 feet tall. Named after their characteristic trumpet shaped flowers in colors ranging from white and yellow to pink and red, the large elliptical leaves and stems emit a strong odor when crushed, likely a warning to predators of their toxic alkaloid content.

Angel’s trumpet is an evergreen of the Brugmansia species that contains toxic alkaloids. When ingested by your horse, these alkaloids can cause interruptions in gastrointestinal function and hallucinations, resulting in severe colic and abnormal behavior.

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Symptoms of Angel's Trumpet Poisoning in Horses

Symptoms of a poisoning are related to dysfunctions in the nervous system, and can often be seen in an absence of the “fight or flight” response. An affected horse at rest develops severe cases of colic and delirium, interrupting their normal activity. Signs your horse has been poisoned by angel’s trumpet include:

  • Dehydration
  • Dry mouth
  • Dry mucous membranes
  • Constipation
  • Intestinal bloating
  • Delayed gastric emptying
  • Decreased or absent gut sounds
  • Impaction colic 
  • Depression
  • Musculoskeletal Weakness 
  • Sweating
  • Abnormal behavior 
  • Dilated pupils
  • Blurred vision
  • Incoordination
  • Disorientation
  • Delirium 
  • Rapid heart rate
  • Increased body temperature
  • Respiratory failure
  • Convulsions
  • Coma

Causes of Angel's Trumpet Poisoning in Horses

The cause of toxicity from ingestion of angel’s trumpet is due to toxic amounts of tropane alkaloids, which are contained within all parts of the plant. These alkaloids include scopolamine, hyoscyamine, and norhyoscine. Once ingested, these alkaloids antagonize the cholinergic receptors, which directly affect the nervous system, heart, digestive system, and the eyes. Gastrointestinal contractions are then interrupted, which causes a build-up of fluid within the stomach, creating severe impaction colic. The tropane alkaloids also have hallucinogenic properties, which explains why you may see your horse stumbling around in a delirious state.

Diagnosis of Angel's Trumpet Poisoning in Horses

Diagnosis of an angel’s trumpet poisoning is fairly easy if you know your horse has ingested this toxic plant. Be sure to bring a sample of the plant you believe your horse has ingested in to your equine veterinarian clinic for a positive identification. Symptoms can reveal a tropane alkaloid toxicity as well, especially with the presence of dilated pupils with the severe colic, and can help to differentiate this condition from other causes of colic. Other tests can include blood work and serum testing, urinalysis, a rectal examination for signs of impaction, and analysis of fluid obtained through an abdominocentesis. Many of these tests can reveal the presence of toxic alkaloids. Examination of the mouth of your horse as well as fecal matter may reveal particles of the plant itself, leading to a diagnosis.

Treatment of Angel's Trumpet Poisoning in Horses

There is no antidote for the tropane alkaloids contained in angel’s trumpet, therefore treatment is symptomatic and supportive. Hospitalization may be necessary. Activated charcoal can be administered to reduce the absorption of the toxic alkaloids, typically through a nasogastric tube. Fluid therapy and laxatives can be given, as well as pain relievers, and are often administered until any discomfort and impaction colic is resolved. 

An acetylcholinesterase inhibitor drug (AChEI) is often used to counter the tropane alkaloid effects. Neostigmine can be administered, but physostigmine is more often given, due to its ability to more easily pass the blood-brain barrier to eliminate delirium and coma. Parasympathetic stimulants may also be prescribed to reverse some of the symptoms.

Recovery of Angel's Trumpet Poisoning in Horses

Due to the possible fatal nature of this type of toxicity, recovery depends on the amount of the toxin ingested and how quickly treatment can be administered. Your veterinarian will discuss with you your horse’s outlook for recovery based on his specific circumstance. You will likely be given medications to administer once your horse is stabilized to aid in his full recovery. 

Angel’s trumpet, much like jimsonweed and all Datura flower species, contains enough tropane alkaloids to cause serious problems for your horse, and as such, preventing an exposure should be a top priority. While it is not a plant that horses normally seek out, ingestion of this toxic shrub is often due to an accidental feed or hay contamination, or if your horse cannot find other preferable green vegetation to eat. Regularly inspecting all hay and feed that comes onto your farm for angel’s trumpet and other toxic plants can greatly reduce your horse’s chances of ingesting them. Other measures to ensure your horse’s safety include:

  • Learn to recognize angel’s trumpet and monitor your property for the plant
  • Remove angel’s trumpet from pastures, fence lines, and trails your horse may frequent through herbicides, mowing, and manual removal
  • Provide fresh and safe green vegetation, feed, and hay
  • Be sure all your horse’s mineral needs are met
  • Ensure that your horse’s pastures do not become overgrazed