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What is Marsh Marigold Poisoning?

Marsh marigolds are not particularly tasty to most equine and, because of this, fatalities are not common.  This acidic tasting plant is generally only consumed when the pastures to which horses have access are over-grazed or when other more desirable sources of forage unavailable.  The toxin contained in marsh marigolds is highly irritating to the skin and similar tissue surfaces.  Extreme exposure to, along with consumption of this plant is generally fatal.

Marsh marigold poisoning in horses, a member of the buttercup family, is toxic to horses and humans when any portion of the mature plant is ingested.  The toxin is highly alkaloid in nature.

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Symptoms of Marsh Marigold Poisoning in Horses

Symptoms of marsh marigold poisoning in horses will depend upon the amount and duration of consumption of the plant.  Here are some of the symptoms which have been reported to some degree:

  • Stomach upset
  • Acute inflammation of the gastrointestinal tract
  • Restlessness
  • Colic
  • Depression
  • Nervous excitation
  • Twitching of eyelids
  • Bloody urine
  • Diarrhea

More advanced symptoms include:

  • Weak pulse
  • Decreased breathing
  • Weakness 
  • Convulsions
  • Death

Types  

The types of marsh marigold poisoning relate to the extent to which the horse has been poisoned:

  • Mild - Cases in which only small amounts have been consumed - typically result in good prognosis within 24 to 48 hours
  • Acute - Cases in which large amounts have been consumed - fatal within 6 to 12 hours after convulsions begin

Causes of Marsh Marigold Poisoning in Horses

The cause of marsh marigold poisoning in horses is alkaloid in nature.  The offending toxin is protoanemonin which is released when the plant is crushed with an enzymatic process such as that which takes places when eaten and digested by the horse, cattle or human host. Protoanemonin is a yellow, bitter tasting oil that is highly irritating and inflammatory to any body tissue with which it comes into contact.

The oral and throat tissues, as well as the tissues of the gastrointestinal tract, wreak the havoc of the acrid tasting oil sometimes even causing the eventual death of the host.  The plant in its young, growing stage is less harmful than the mature, flowering plant.  While the buttercup is acrid-tasting as well as poisonous, the mature stage of the marsh marigold contains a poison that is much more potent and is more dangerous even in smaller quantities.

Diagnosis of Marsh Marigold Poisoning in Horses

Diagnosing marsh marigold poisoning in your horse will not be an easy task for your veterinary professional as many toxic plants will exhibit similar clinical signs and symptoms.  Additionally, there usually aren’t any lesions to examine in many of the toxicity situations, whether the animal is still alive or dead when the physical examination is done by your vet or other veterinary professional.  Lab testing can be attempted to ascertain if there are abnormal levels or imbalances in minerals and other blood and biological components but there aren’t usually many definitive markers.  

Your complete and thorough history will be invaluable to the final diagnosis of the type of poisoning from which your horse is suffering. Frequently, the best diagnosis will only come after the plant has been positively identified as one which was available and accessible to the afflicted horse.  This task may even involve locating parts of chewed plants to make that positive identification and making them available to your vet.

Treatment of Marsh Marigold Poisoning in Horses

Once your veterinary professional has ascertained the plant or substance which has caused the poisoning, an appropriate treatment plan will be developed and initiated.  Unfortunately, there are no real medications which can be administered to cure or reverse the poisoning symptoms in your horse.  Attempts to ease or treat the gastroenteritis or nephritis could include the use of activated charcoal  as an absorptive measure to facilitate the removal of the toxin from the horse’s digestive system, diuretics as well as substances to ease the gastric discomfort could be given.  

Symptomatic treatments of cardiorespiratory medications may be given to prevent asphyxiation. Of course, removal of the horse from the source of the poisoning, fluids, and rest will also be recommended.  The duration and the quantity of the marsh marigold plant which the horse has consumed will play a vital role in successful treatment of this poisoning.  Your veterinary professional will want to start treatment before the more advanced symptoms noted above present.

Recovery of Marsh Marigold Poisoning in Horses

The timing of treatment and any other medical intervention is vital for the survival of your afflicted horse.  The good thing about this particular poisonous plant is that it isn’t particularly tasty to your horse, making it not a first choice for food unless food and forage is otherwise scarce.  If you notice the above symptoms and get medical care sooner rather than later, your horse has better chance of survival.

Also, vital to the health, performance and production of those horses remaining in your herd, is the identification of this and other poisonous plants which may be accessible to them as they graze.  The dry variety of this particular poisoning plant doesn’t seem to carry the same potency of the toxin, making it not as emergent a situation if it gets mixed into the pasture hay that may be part of the customary feeding regimen.