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What is Cressleaf Groundsel Poisoning?

Cressleaf groundsel is also known as butterweed, yellow top, golden ragwort or yellow ragwort. The cressleaf groundsel weed has purple stems and bright yellow flowers.  It grows to approximately 16 feet tall. All the different parts of the weed are toxic but the flower has a higher concentration of pyrrolizidine alkaloids.  

Long term consumption of cressleaf groundsel will cause irreversible liver damage and can be fatal.  If your horse is showing signs of cressleaf groundsel poisoning or if you have seen your horse consuming a yellow flowered weed, he should be seen by a veterinarian as soon as possible.

The weed cressleaf groundsel (Senecio glabellus) contains the compounds pyrrolizidine alkaloids which are extremely toxic if ingested. Cressleaf groundsel is poisonous to humans and to most animals, including cattle and horses.

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Symptoms of Cressleaf Groundsel Poisoning in Horses

Symptoms may include:

  • Depression
  • Behavior changes
  • Loss of appetite
  • Weight loss
  • Aimless walking
  • Poor hair coat
  • Incoordination
  • Diarrhea
  • Head pressing ( pressing his head against a wall or post)
  • Blood in urine
  • Liver damage

Causes of Cressleaf Groundsel Poisoning in Horses

ressleaf groundsel poisoning is caused by the continual ingestion of the toxic weed. Typically, horses usually do not ingest the cressleaf groundsel weed because it is not very palatable.  Reasons a horse may eat the cressleaf groundsel are:

  • Overgrazed pasture, no other plants to forage on
  • Overgrown pasture, cressleaf groundsel is mixed within the good grasses

Diagnosis of Cressleaf Groundsel Poisoning in Horses

The veterinarian will go over your horse’s medical history.  He will need to know the timeline of the symptoms. The veterinarian may want to see the pasture where the horse forages. He will want to identify the groundsel plant and other noxious weeds that may be present.

The veterinarian will examine the skin and fur of your equine, looking for a decline in the typical coat. If you have noticed behavioral changes that are significant to groundsel poisoning such as depression, head pressing, or lack of coordination, relay the information to the veterinarian so that he may evaluate these characteristics in your horse.

The veterinarian will want to take a urine sample for analysis, and if time permits, blood test results may reveal changes in liver function indicative of cressleaf groundsel toxicity. Because this plant is sometimes harvested in hay, your veterinarian may want to see the hay that is given to your horse.

Treatment of Cressleaf Groundsel Poisoning in Horses

If cressleaf groundsel poisoning is diagnosed, treatment will be mainly supportive and the outcome will depend on severity of the poisoning. In some cases, the veterinarian may want to administer activated charcoal which helps to prevent the further absorption of the toxin entering the patient’s organs and bloodstream.  A dextrose intravenous may be started to aid the horse to stay hydrated. Supportive medications for the clinical signs will be given if needed.

Once your horse is stable, the veterinarian may suggest taking an ultrasound of the abdomen area.  The ultrasound will help determine the condition of the liver.  If the liver has severe damage, the veterinarian may recommend humane euthanasia.  Unfortunately, in most instances, by the time the cressleaf groundsel poisoning is discovered, the liver is beyond repair.

However, if the condition of the liver is not severe, the veterinarian may recommend treating your horse for liver damage.  The liver damage can be irreversible but supportive treatment can improve quality of life.  The veterinarian may suggest feeding your horse a low protein diet.  Daily vitamin B, potassium, zinc, and amino acids will help clean the intestines of endotoxins (what a healthy liver usually does). There are also herbs that can also be beneficial such as burdock and/or milk thistle powder.

Recovery of Cressleaf Groundsel Poisoning in Horses

Patients that have been ingesting cressleaf groundsel for an extended period of time have a guarded prognosis. During the follow-up visits, the veterinarian may suggest that the horse has another ultrasound taken as well as blood tests to evaluate the function of the liver.

It is important to remove the cressleaf groundsel weed from the pasture to prevent the reoccurrence of poisoning.  The pasture must be maintained on a regular basis. Any toxic plants and weeds must be removed to ensure the safety of your horse. Plants may be removed manually or with herbicides.  

An agricultural agent can help you determine what plants are toxic to your horse.  He can also recommend what plants should be available for the horse to forage on.