Horseradish Poisoning in Horses

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

What is Horseradish Poisoning?

While horseradish is useful in humans and can be utilized as antimicrobial, antiseptic, diaphoretic, diuretic, and a cardiovascular and gastrointestinal agent, it isn’t necessarily useful in the equine body.  When ingested by the horse, components in this pungent and sharp plant get change in the digestive system and the sinigrin is converted into mustard oil.  Mustard oil is a toxin which causes sickening similar to another member of its family, wild mustard.  Fortunately, this plant isn’t the most tasty and not a forage of first choice for most horses unless it gets mixed up with good forage, or the lush green forage is reduced by overgrazing or seasonal changes.

Horseradish is a vegetable that contains vitamin C, asparagine, resin, and sinigrin (which converts to mustard oil).  It is the conversion to mustard oil which causes it to be poisonous to horses.

Symptoms of Horseradish Poisoning in Horses

A member of the Cruciferae (Brassicaceae) family, horseradish (Armoracia Lapathifolia) can cause symptoms similar to those of wild mustard.  Here are some of those you might see, based upon the particular species of plant in this family which has been ingested:

  • Gastroenteritis
  • Pain
  • Salivation 
  • Diarrhea
  • Disturbances of the upper digestive tract
  • Irritation and inflammation of the oral tissues

Additionally, some species in this family have been known to cause:

  • Hemolytic anemia - A disorder of immune system that affects the maintenance of red blood cells
  • Hemoglobinuria - Blood abnormalities
  • Goitrogenic substances - Have negative effects on thyroid


The types of this poisoning pertain to the species of this family which your horse has consumed.  This botanical family consists of a number of ornamentals and vegetables such as:

  • Brussels sprouts
  • Cabbage
  • Chinese cabbage
  • Kale
  • Kohlrabi
  • Mustard
  • Rutabaga
  • Turnip
  • Watercress
  • Radish
  • Horseradish
  • Japanese horseradish
  • Crambe (oil seed)

The symptoms noted above can vary in intensity depending on the quantity and part of the horseradish plant which has been ingested by your horse and, if not caught and medical attention given, can ultimately be fatal for your horse.



Causes of Horseradish Poisoning in Horses

The cause of horseradish poisoning in horses lies in the digestive process of a toxin called sinigrin.  In the horse’s gastrointestinal tract, the sinigrin gets converted into mustard oil (allyl isothiocyanate) which is poisonous, causing the gastrointestinal symptoms. Additionally, sometimes mustard oils can contain what is considered toxic concentrations of nitrates which further complicate the poisonous process.



Diagnosis of Horseradish Poisoning in Horses

Your complete history will be required by your veterinary professional as he collects his diagnostic information. This history will need to include dietary and feeding information like the type of feed offered, the frequency of feedings, whether the horse is turned out for pasture or field forage or if it is fed a hay and grain diet.  You will likely need to determine the potentially poisonous plants which are within access of your horse, samples being provided if necessary.  This will help the vet pinpoint the possible source of the poisoning or sickening of your horse.  He will do a physical examination of your equine and assess the condition of it.  

The veterinarian may need to collect blood and tissue samples for laboratory testing to determine if any of the blood components are out of balance, to determine if there are any bacterial or fungal components in the poisoning and to determine if there is any parasitic activity involved.  Since many of the symptoms of this poisoning are similar to many other conditions and diseases known to horses, he may order radiographic imaging (x-rays) and CT imaging to rule out other causes.  Once he has gathered all of this information , he can formulate and implement an appropriate treatment plan for your horse.



Treatment of Horseradish Poisoning in Horses

The treatment plan will include removing the horse from the source of the poisoning.  This step is the first one taken perhaps even before the arrival of the vet.  This step will include not only removing the horse from the pasture or field if that is where he had access to the horseradish but also providing the afflicted horse with plenty of clean, fresh water and nutritious and safe feed.  The vet will likely recommend supportive care that includes the above, rest and a safe place to heal, fluids given either via IV or orally, and close observation while the horse recuperates.  

If the diarrhea continues or is considered an ongoing problem, he may wish to treat with an anti-diarrheal medication to stem the loss of fluids.  There is no antidote for poisoning which occurs with ingestion of plants from the horseradish family and the survival of your horse will depend upon the amount of the herb that was consumed and how quickly medical care was provided.



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Recovery of Horseradish Poisoning in Horses

As noted above, the survival of your horse is dependent on the amount consumed and the rapidity of which the medical care was provided.  It is vital that you make yourself aware of any possible poisonous plants which may be within grazing access to the rest of your herd so that repeat episodes will be less likely to occur.  Also, you need to check the hay and grain that you feed your herd for possible mixture of any of these poisonous plants into it since these plants are very prolific in pastures and field out of which hay or grain may be harvested.  It is important to make the pastures, fields, hay and grain as safe as possible for the health, performance and productivity of your herd.



Horseradish Poisoning Questions and Advice from Veterinary Professionals

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