Cardiac glycoside toxicity

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Cardiac Glycoside Toxicity

Cardiac Glycoside Poisoning

Cardiac glycoside toxicity is caused by consumption of cardiac glycoside-containing plants. These include 11 different plant families which include Apocynaceae, Asclepiadaceae, Celastraceae, Brassicaceae Lilaceae, Moraceae, Fabaceae, Ranunculaceae, Scrophulariaceae, Sterculiaceae, and Tiliaceae. Within the 11 plant families, there are a handful of plants that are most likely to be the cause of poisoning in horses.

Since oleander poisoning is one of the most frequent causes of plant poisoning in animals, it is also discussed separately.

Upon ingestion of cardiac glycoside-containing plant parts, horses may either be found dead or develop primarily heart and digestive disturbances just prior to death. A variety of cardiac arrhythmias and heart block, including ventricular tachycardia and first- and second-degree heart block, may be encountered with cardiac glycoside poisoning. Colic and diarrhea may also be seen in horses poisoned with cardiac glycosides. The duration of clinical signs will usually not exceed 24 hours before death occurs.

Symptoms

Colic
Lethargy
Weakness
Diarrhea (sometimes bloody)
Abnormal heart beat and weak pulse
Profuse sweating
Difficulty breathing
Cold extremities
Sudden death

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Laboratory tests

Treatment

TherapiesDetails
Activated charcoal
Magnesium sulfate by mouth
Supportive care
Keeping the horse calm and confined in a quiet area
Antiarrhythmic drugs for cardiac irregularities

Prevention

  • Cardiac glycosides should not be planted anywhere near where horses are kept
  • Fallen leaves or clippings should not be placed near horse paddocks.
  • Make yourself aware of the weeds and plant species that can be invasive in pastures and/or poisonous to horses.
  • Take periodic walks around pastures to check for the presence of potentially poisonous plants
  • Check that hay does not contain dried up poisonous plants
  • If you borrow or hire farm machinery ensure it is clean prior to arriving on your property, the same goes for lending of your own equipment.
  • Quarantine new animals in a separate paddock the first 10 days to 2 weeks after arrival. Weed seeds can be passed through an animal's digestive tract.

Prognosis

Poor. Horses that survive cardiac glycoside poisoning may be left with permanent heart damage.

Scientific Research

General Overviews

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Risk Factors

  • Keeping flower gardens directly adjacent to horse paddocks
  • Allowing horses access to garden cuttings
  • Keeping horses in overgrazed pastures with access to cardiac glycoside containing plants

Seasonality

WinterSpringSummerAutumn

Also Consider