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What is Rayless Goldenrod Poisoning?

Most cases of rayless goldenrod poisoning have been reported in late fall and winter when forage is sparse and most horses are fed more hay. Rayless goldenrod poisoning can be life threatening and it only takes a small amount of the plant for your horse to experience severe symptoms. The effects of the toxin are cumulative and therefore long term ingestion of even small amounts can result in the death of your horse. Death can occur from one day to three weeks after the first symptoms appear.

Rayless goldenrod is a deciduous shrub that has several branches growing from a woody, stout root crown. The branches can be between two and four feet tall. New branches will be gray or white. Yellow flowers will appear in clusters on the branch tips from August to October.

Rayless goldenrod is more commonly known as jimmy weed and is a multi-stemmed plant that is a perennial. It is very toxic to horses. Horses will develop a condition known as trembles when they are experiencing rayless goldenrod poisoning. 

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Symptoms of Rayless Goldenrod Poisoning in Horses

It is extremely important that you contact your veterinarian as soon as you notice any of these symptoms. Failure to act quickly may result in the death of your horse. Remove your horse from their pasture and keep all food away until your veterinarian arrives.

  • Trembling muscles in the nose, legs and shoulders
  • Stiffness or standing humped up
  • Shaking of the whole body
  • Depression
  • Intoxication 
  • Lethargy
  • Constipation
  • Throat paralysis and choking
  • Colic
  • Labored or rapid breathing
  • Constant dribbling of urine
  • Dark brown urine
  • Bloody or dark, tarry feces
  • Smell of acetone on the breath
  • Cardiac abnormalities
  • Congestive heart failure
  • Cardiac arrest
  • Death

Causes of Rayless Goldenrod Poisoning in Horses

The toxin found in rayless goldenrod is called trematol. Trematol is an alcohol that is found throughout the plant, even when the plant is dried or inactive. It is toxic to all livestock; young stock can become poisoned from drinking the milk of animals that have been eating rayless goldenrod. Humans can also become poisoned when they drink the milk of animals that have eaten rayless goldenrod; children are more susceptible than adults.

Diagnosis of Rayless Goldenrod Poisoning in Horses

There are no specific tests that can verify that your horse has been poisoned by rayless goldenrod. Your veterinarian will complete a full physical examination and begin ruling out other possible diseases or toxins. This will be done by doing a complete blood count, urinalysis, and fecal examination.

The main diagnostic tool that your veterinarian will use when diagnosing rayless goldenrod poisoning is their knowledge of the toxin, trematol. By looking at the symptoms that have presented, your veterinarian will be able to determine that your horse has ingested rayless goldenrod. The smell of acetone on your horse’s breath and the trembling of the muscles in their nose, legs and shoulders will allow your veterinarian to confidently diagnose your horse with rayless goldenrod poisoning.

Postmortem necropsy can be done to make a definitive diagnosis of rayless goldenrod poisoning. Necropsy is the animal version of a human autopsy.

Treatment of Rayless Goldenrod Poisoning in Horses

Your veterinarian will recommend hospitalization for your horse since medications will probably be administered through a stomach tube or by injection. 

The treatments for rayless goldenrod poisoning will be either symptomatic or supportive since there is no set treatment or antidote. Remove your horse from any food source that could be tainted with rayless goldenrod. If you see any identifiable plant matter in your horse’s mouth, flush their mouth with water to remove the plant matter. 

A gastric lavage should be done along with giving activated charcoal to prevent any remaining toxins in the stomach from being absorbed by the body. During this time all exercise and excitement should be prevented to give your horse a calm setting. If your horse is a lactating mare, remove her foal and repeatedly mild her and dispose of the contaminated milk. This will also help remove the toxins from the body.

Supportive care will include fluid and nutrition therapy. Your veterinarian may also prescribe a laxative, if your horse is not suffering from diarrhea, to help purge their body of the toxins.

Recovery of Rayless Goldenrod Poisoning in Horses

Prognosis for your horse will largely depend on the amount of rayless goldenrod that was ingested and how quickly treatments began. Your veterinarian will have an accurate prognosis for your horse once treatments have begun and they see how well your horse is responding to those treatments.

Be a proactive horse owner and practice proper pasture maintenance. Walk through your horse’s pasture at least once a month and remove any plants that could be potentially poisonous to your horse. Know what is in your horse’s hay. If you cut hay yourself be sure to inspect your hay field for poisonous plants. If you purchase hay, examine the hay and ask about what plants are in the field it was cut from.