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What is Stinkwort Poisoning?

Stinkwort is found throughout the United States and in southern parts of Canada. It is found in other countries as well, but not as prevalent. Your horse will usually avoid stinkwort since it does not have a very palatable taste. 

If your horse eats stinkwort, they can become poisoned and death can occur. The mature plants with seeds are the most toxic to your horse. There are fine hairs on the seeds of stinkwort that will cause pulpy kidney in your horse. It can also cause fatal bacterial enterotoxaemia. 

Horses that ingest stinkwort can become erratic and in some instances violent. This is because the toxins within the stinkwort plant can cause hallucinogenic episodes and problems within the central nervous system.

Stinkwort is known by several different names including jimson weed, camphor inula, kaapse-kakiebos and stinkweed. Stinkwort is a very toxic plant, even to humans, and should be handled with care. When removing stinkwort from your horse’s pasture, wear gloves and long sleeves to keep the plant from touching your skin. Dermatitis will occur if the plant touches your skin.

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Symptoms of Stinkwort Poisoning in Horses

Symptoms of stinkwort poisoning can begin to appear within minutes of your horse ingesting the plant. If you notice your horse eating stinkwort or you see any of these symptoms, contact your veterinarian for an emergency call.

  • Dilated pupils
  • Agitation
  • Increased heart rate 
  • Excessive thirst
  • Trembling
  • Convulsions
  • Coma
  • Pulpy kidney
  • Dermatitis
  • Behavioral changes
  • Restlessness
  • Nervousness
  • Frequent urination
  • Death

Causes of Stinkwort Poisoning in Horses

Stinkwort contains the toxins atropine and scopolamine. These toxins are from the tropane alkaloid family and will affect the central nervous system. This will include problems with the heart and also muscle control. 

While stinkwort is not palatable to your horse, they will eat it if their pasture is sparse and there is no other option for them to forage. Stinkwort remains toxic even when dry and it has been known to make its way into cut hay and be baled and fed to horses. Be sure you thoroughly check your hay field prior to cutting for any potentially poisonous plants. If you purchase your hay, verify that the field it was cut from was checked prior to cutting.

Diagnosis of Stinkwort Poisoning in Horses

While you are waiting for your veterinarian, remove your horse from their pasture and place them in a clean, well bedded stall that is quiet. Do not give them any food or hay until your veterinarian assesses your horse. Try to keep your horse calm.

Your veterinarian will begin looking for clues in the symptoms that your horse has already presented. They will ask you questions about your horse’s medical history and their eating habits. If possible, have samples of your horse’s food and hay available for your veterinarian. 

Your veterinarian will do a physical examination that will include a complete blood count, fecal test and urinalysis. Your veterinarian may also want to walk your horse’s pasture searching for the cause of their illness. Finding the stinkwort plant in your horse’s pasture will help in definitively diagnosing stinkwort poisoning in your horse.

Treatment of Stinkwort Poisoning in Horses

The first step in treating stinkwort poisoning is to remove your horse from the pasture and provide a nutritious feed for them. Stall rest may be recommended while your horse is being treated. 

In severe cases, hospitalization may be highly recommended where supportive care can be properly administered. Your horse may require IV fluid and nutrition therapies as well as intravenous medications to try and counteract the toxins. 

While there is no antidote for stinkwort poisoning, your veterinarian will treat the symptoms that have presented and use activated charcoal to absorb and bind any toxins still left in your horse’s stomach. 

Keep your horse calm and quiet while they are recovering from stinkwort poisoning. Be sure to give all prescribed medications as directed and if you have questions regarding treatments or medications, ask your veterinarian.

Recovery of Stinkwort Poisoning in Horses

The general prognosis for stinkwort poisoning is good with the exception of extreme cases or those who have not sought medical attention. In those cases, the prognosis is poor to guarded. 

Be sure to eradicate any stinkwort plants from your horse’s pasture or any area where your horse can reach. When you are removing stinkwort wear protective clothing such as gloves, pants, long sleeve shirt and closed toed shoes. Pull and burn any visible plants and then use a pasture safe herbicide to ensure that all the roots have been eradicated.