Burrow Weed Poisoning in Horses

Burrow Weed Poisoning in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost
Burrow Weed Poisoning in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

What is Burrow Weed Poisoning?

Burrow weed is also referred to as Jimmy weed and rayless goldenrod.  The scientific name for burrow weed is haplopappus heterophyllus.  Burrow weed is a small bush with clusters of yellow flowers.  The leaves are very sticky and narrow and the plant is toxic when it is green and dried.

Burrow weed grows in dry rangelands, drainage areas and river valleys. It can be found in New Mexico, Colorado, Texas and Arizona. Burrow weed is also poisonous to other animals and humans. If a mare forages on burrow weed she can pass the toxin in her milk to her nursing foal.

If your horse is showing symptoms of burrow weed poisoning, remove him from the pasture he has been foraging in.  He needs to be seen by an equine veterinarian as soon as possible. Burrow weed poisoning in horses can be fatal.

Burrow weed contains the toxin tremetol, which if ingested, is poisonous to horses. The toxin tremetol causes damage to the body’s muscles, especially to the heart. The heart is composed of cardiac muscles.

Symptoms of Burrow Weed Poisoning in Horses

Symptoms may include:

  • Hind leg weakness
  • Knuckling at the fetlocks
  • Posterior paralysis
  • Muscle tremors
  • Lethargy
  • Depression
  • Anxiousness
  • Incoordination
  • Elevated heart rate
  • Stiff gait
  • Sweating
  • Quidding
  • Recumbent position (leaning or reclining) 
  • Edema
  • The horse’s breath smells like acetone
  • Respiratory distress
  • Heart failure
  • Incontinence 
  • Inability to swallow
  • Coma
  • Collapse
  • Death


Causes of Burrow Weed Poisoning in Horses

Burrow weed poisoning is caused by the ingestion of the plant.  Burrow weed is not a palatable plant. The reasons a horse would ingest this toxic plant would be:

  • Neglected pasture becomes overgrown with burrow weed 
  • No other plants for the horse to forage on
  • Burrow weed is mixed in his feed  (it is important to only buy feed from a reputable distributor)
  • Foal nurses on a mare that has foraged on burrow weed


Diagnosis of Burrow Weed Poisoning in Horses

If the veterinarian suspects burrow weed poisoning, he will recommend a complete blood count , a serum chemistry panel and a urinalysis.  Patients with burrow weed poisoning will have elevated levels of myoglobin in their blood and urine.  Myoglobin is a protein normally found in muscles; the toxin breaks down the muscles. The serum chemistry panel can help assess organ function.  The veterinarian may take the patient’s pulse, blood pressure and listen to the heart with a stethoscope. The doctor may also palpate the horse’s stomach and limbs.



Treatment of Burrow Weed Poisoning in Horses

The veterinarian will want to get an intravenous started.  The IV will help deliver fluids to the horse, which will assist in maintaining his electrolytes at a normal level.  The patient may be given activated charcoal orally which can help prevent more toxins from entering the bloodstream.  The veterinarian may administer several doses of activated charcoal to the patient.

To help remove any remaining toxins in the gastrointestinal tract the veterinarian may give the horse sorbitol as a laxative to encourage bowel motility and further removal of toxins.  Once the horse is stable the veterinarian may want to transport him to an equine hospital, where he can receive intensive care 24/7. If the patient is hospitalized the veterinarian may also request that an echocardiogram be performed.  This diagnostic test can help evaluate the damage the toxin has done to the horse’s heart.



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Recovery of Burrow Weed Poisoning in Horses

Horses that are diagnosed and treated in the early stages of burrow weed poisoning have a better recovery prognosis. Patients with severe cases of burrow weed poisoning have a guarded prognosis.

The patient will need follow up visits to monitor his progress.  If the EKG determined myocardial lesions, the veterinarian may suggest that the horse be seen by an equine heart specialist. Myocardial lesions are not irreversible; they cause permanent to damage to the heart.

It is important that burrow weed poisoning does not occur again.   The toxic plant must be permanently removed from the pasture.  Pastures must be maintained regularly to prevent toxic weeds and plants from taking over the pasture. The horse has to have good plants to forage on including tall grass, legumes and forbs so that he will not forage on unpalatable toxic plants. 

Toxic plant poisoning in horses and cattle can be prevented with proper pasture management.  If you are uncertain what plants are toxic, call your local agriculture agent.  Not only will he help you identify the plants that can be fatal to your animals, he will also make recommendations on what plants will be beneficial.



Burrow Weed Poisoning Questions and Advice from Veterinary Professionals

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