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What is Goat's Rue Poisoning?

Goat's rue, or Galega officinalis, is a herbaceous legume that is native to the middle east but was introduced in Utah as a forage crop in the 1890 and has since spread to nine additional states. It has lanceolate leaves on tall stems adorned at the top with miniature sweet pea flowers, usually in lavender. Unfortunately, this plant also contains alkaloids such as galegine which can cause the inability to properly process foods, leading to dangerous drops in blood sugar levels.

Galega officinalis, known more commonly as goat’s rue, contains an alkaloid by the name of galegine which can cause dangerous drops in blood sugar when consumed in large quantities.

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Symptoms of Goat's Rue Poisoning in Horses

Although this plant has been used as a traditional remedy for humans and livestock for several disorders, if ingested in sufficient quantities it can produce symptoms such as:

  • Breathing difficulty
  • Foul breath
  • Hair loss
  • Lethargy 
  • Low blood pressure
  • Stiff joints
  • Weight loss

Negative consequences are more common in sheep than other animals, although cattle, horses, and goats can all have reactions as well.

Types 

Galega officinalis, more commonly known as goat’s rue or french lilac, has been used for much of history as a medical treatment in horses and humans. It has been used quite frequently as a remedy for diabetes as it prevents the absorption of carbohydrates which, in turn, reduces the circulating glucose sugar levels in the blood. It’s efficiency in reducing blood sugars led to the development of man-made medications utilized to treat diabetes and one of these medications, Metformin, is available today although its use is controversial. Goat’s rue has also traditionally  been used to increase milk production for livestock.

Causes of Goat's Rue Poisoning in Horses

The alkaloid in goat’s rue that causes the damage is called galegine. This chemical can reduce blood pressure to dangerous levels as well as inhibit the absorption of glucose into the blood from the digestive system. When this removes too much sugar from the bloodstream, the liver uses its stores of glycogen, and symptoms of severe hypoglycemia will start to surface.

Diagnosis of Goat's Rue Poisoning in Horses

The identification of the Galega officinalis, either in the pasture or mixed into the feed, will help to make a preliminary diagnosis. The examining veterinarian will need to gather as much information as possible regarding the amount of plant material that was consumed and how long it has been since the ingestion of the toxin. A comprehensive history of the animal in question will also be required. This history will ll provide as much knowledge as possible to the evaluator about the horse’s medications, diet, and environmental elements. 

Standard blood tests, including a complete blood count and biochemistry profile, will need to be evaluated to see if any sugar imbalances or infections are present as well as establishing what levels of liver and kidney enzymes are found in the patient’s blood. These tests are likely to show high levels of lactic acids and may also reveal imbalances in the blood sugar. A urinalysis is likely to uncover the presence of ketone bodies in the urine as well.

Treatment of Goat's Rue Poisoning in Horses

If the animal ingested large quantities of goat’s rue within the last few hours, then your horse’s doctor may choose to perform a gastric irrigation procedure in order to remove as much of the toxic material from the digestive system as possible. It is also customary to administer activated charcoal to the patient in poisoning situations, as it can prevent further absorption of the galegine alkaloids into the bloodstream. No specific antidotes are available for the toxic compounds that are produced in the galega officinalis plants, so treatments beyond decontamination be will generally be focused on supportive therapies. 

Frequently utilized measures that are employed for supportive treatment include IV fluids to prevent dehydration and combinations of electrolytes and sugars in order to adjust for any imbalances that may have developed, such as low blood sugars. It is also important to remove the goat’s rue from the patient’s diet, whether the horse is accessing the plant in the pasture or if it is being administered as a remedy.

Recovery of Goat's Rue Poisoning in Horses

Fortunately, goat’s rue has a generally unpleasant taste to most horses, and they tend to avoid eating it, often even when it is mixed in with hay or feed, so poisonings are rare. It can also take a relatively large quantity of the the toxin to become lethal, around 30-50 milligrams of plant material per kilogram of horse. Because the plant is toxic, particularly for sheep, this plant is classified noxious not only on the noxious weed list for thirteen states but also as a federal noxious weed as of 2008.