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What is Snakeweed Poisoning ?

Also known as broom snakeweed, broomweed, and turpentine weed and with the botanic name Gutierrezia sarothrae, snakeweed is from the family Asteraceae. Snakeweed can be found in the dry plains and foothills from 4,000 to 10,000 feet in elevation and has been found to be poisonous to horses, cattle, sheep and goats.

Snakeweed is a perennial that is shrubby at the base and then reaching 18 to 24 inches in height. The stems branch out and the leaves are linear and smooth. There are typically multiple heads in clusters at the ends of each branch. The flowers are yellow and 3-8 ray flowers and 3-8 disc flowers (that bloom from August to October) will be present on each head. In rangeland that has been overgrazed, snakeweed will often form dense stands.

Snakeweed, or Gutierrezia sarothrae, contains saponin that is poisonous to horses when ingested, causing diarrhea and in some cases, abortion in pregnant mares.

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Symptoms of Snakeweed Poisoning in Horses

Should your horse ingest snakeweed, he may develop diarrhea, followed by his becoming constipated. Other symptoms include:

  • Red blood cells found in urine
  • Appearing listless
  • Nasal discharge with crusting
  • Rough hair coat
  • Necrosis of the liver
  • Presence of jaundice in the eyes 

Should a horse experience snakeweed poisoning when pregnant, they may experience vulvar swelling and the poisoning may lead to the death of the foal they are carrying. In some cases, the foal is born alive but is very weak and may pass away a few days later.

Types 

Your horse can experience toxicity in two ways from ingesting snakeweed. Saponins that are present in snakeweed can lead to poisoning in your horse. In addition, your horse can experience toxicity from selenium that has been absorbed through the soil by the snakeweed.

Causes of Snakeweed Poisoning in Horses

It is believed that saponins in snakeweed are the toxic component. Saponins are glycosides that have characteristic foaming and are made of a polycyclic aglycone. Saponins are bitter so horses tend to not want to ingest too much. The plant is toxic when green, as well as when dried, though toxicity does seem to vary. It seems that higher toxicity occurs during times of rapid growth, like in early development of leaves as well as when the plant grows in sandy as opposed to calcareous soils. Snakeweed also absorbs selenium which can also cause toxicity in your horse when a significant amount is consumed. 

Diagnosis of Snakeweed Poisoning in Horses

In cases of poisoning, it can be a challenge for your veterinarian to diagnose your horse because many of the substances that are toxic to horses cause similar symptoms. Should you notice concerning symptoms in your horse, it is a good idea to look in the area where he has been roaming to see what plants or trees he may have ingested. Should you find any possible suspects, you can bring a sample with you when having your horse examined.

Your veterinarian will conduct a physical examination of your horse and possibly conduct testing on a fecal sample, stomach contents or body tissues. The sample of what your horse may have ingested can help your veterinarian narrow down the possible type of poisoning your horse is experiencing.

Treatment of Snakeweed Poisoning in Horses

There is no antidote for snakeweed poisoning. It is important that your horse be kept from the snakeweed and supportive care be administered. To start, your veterinarian will seek to clear out the stomach of your horse to remove the poisoning. Activated charcoal can be administered in an effort to absorb the poisoning so that it is not absorbed by your horse’s body. Quick attention is key in order for less poison to be metabolized and absorbed by your horse.

Gastric lavage can be used to clear any plant particles out of your horse (and these particles can be tested to confirm the type of poison). Fluid therapy may be utilized in order to flush the kidneys and make sure that your horse does not become dehydrated. If necessary, oxygen will be administered. Medication may be recommended to help your horse with any abdominal pain.

Recovery of Snakeweed Poisoning in Horses

After your horse experiences snakeweed poisoning, you will want to be sure that he no longer has access to the plant. Keep an eye on your horse as he recovers and follow any guidance offered by your veterinarian. Consult a local expert in weed control for advice on how to minimize the presence or eradicate snakeweed from your property.