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What is Crown Vetch Poisoning?

Crown vetch can be commonly found as pasture coverage to control soil erosion but it is actually a source of poisoning for your horse if he ingests it.  If you suspect he ingested this plant, the veterinarian will want to perform lab work to check for signs of toxicity.  There are certain diagnostic tests and results specific to this type of plant toxicity.  While there is no antidote to crown vetch toxicity, your veterinarian can offer supportive therapies and treatments.  If caught early and your horse is only showing mild clinical symptoms, prognosis of recovery is good.

While crown vetch toxicity is rare, it can happen.  If you believe your horse has ingested any amount of this plant and is now showing clinical symptoms, you need to contact your veterinarian immediately.

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Symptoms of Crown Vetch Poisoning in Horses

Symptoms of crown vetch poisoning may include:

  • Depression
  • Weakness
  • Reluctance to stand
  • Bloat
  • Enteritis
  • Labored breathing
  • Grunting with respiration
  • Cardiac arrhythmia 

Types

Crown vetch is scientifically known as Coronilla varia.  It is commonly used as soil ground cover and as pasture forage.  It is a member of the legume family that can develop in dense stands in a canopy form of up to 3 feet high.  Stems are hollow and angular with leaves made up of nine to twenty five leaflets.  Flowers bloom in stalked clusters in a variety of colors ranging from white to dark purple.

Causes of Crown Vetch Poisoning in Horses

Crown vetch is a great form of control of soil erosion.  It is also a valuable form of protective cover for wildlife.  However, the seeds contain cardenolide cardiac glycosides.  The seeds have a bitter taste so toxicity by ingestion is uncommon.

Diagnosis of Crown Vetch Poisoning in Horses

To begin her diagnosis, your veterinarian will start by performing a full physical exam.  She will make note of all of his symptoms and get details from you about when they started and if they have been getting worse.  The smallest detail may help her rule out other possible causes of his symptoms.   

She will want to perform lab work so she can check his organ values and levels in his blood.  She will suggest a complete blood count (CBC) and chemistry panel to check for abnormalities.  Depending on the results, she may want to run more in depth blood related tests. The lab work will show an increase in serum creatinine kinase activity if it is crown vetch poisoning.  She will also need to conduct an analysis of urine, semen, tissue and stomach contents for cardiac glycosides.  

If your horse is having heart abnormalities, it would be a good idea to have an echocardiogram done.  It will allow the doctor to see exactly which part of the heart beat is abnormal.  There are multiple types of arrhythmias and diagnosing the correct one will allow for better treatment.

If your horse is experiencing respiratory distress, she will want to take a radiograph of his chest.  This will allow her to see if they are fluid or air filled, and if it is a unilateral condition or bilateral.  In regards to the bloat or enteritis, she may want to take a radiograph of his abdomen or even an ultrasound.  In cases of crown vetch poisoning, you will see hyperemia with or without hemorrhage of the abomasum and small intestine.

Treatment of Crown Vetch Poisoning in Horses

The symptoms your horse is experiencing will determine his treatment.  If he is down or not wanting to move around a lot, keeping him stalled may be a good idea.  It will keep him safe from outside threats and allow you to monitor him closely.  If he is experiencing heart abnormalities, she may put on monitoring equipment to have a constant reading of his heart rhythm.  If he is having breathing issues, she may provide oxygen support or other therapies to help ease his discomfort.

Additional therapies will be determined by the symptoms your horse is experiencing.  She will treat symptomatically as symptoms appear.  She will offer support to ease his pain and keep him comfortable and moving.

Recovery of Crown Vetch Poisoning in Horses

The severity of his symptoms will play a role in your horse’s recovery.  If caught early and treated early, prognosis of recovery is good.  If symptoms are severe and not caught until later, prognosis of recovery declines.  Keeping crown vetch out of your horse’s diet and environment is essential for the wellbeing of your horse.