Selenium toxicity

Attention! This is a potentially life-threatening condition for your horse. Time is of the essence, contact your veterinarian immediately.Find a Vet

Selenium Toxicity

Selenium is essential for horses, however too much selenium can be toxic. Selenium exists naturally in the soil, varying in concentration across different geographical regions. Nearly all plants accumulate selenium from the soil. Some plants, known as selenium accumulators require a large amount of selenium to grow. Their presence in the pasture is a good indicator that the selenium levels are high. However another danger is that certain times of the year, these selenium accumulating plants may appear appetizing to horses. Through consuming these plants, horses ingest varying elevated levels of selenium causing differing levels of toxicity. Horse owners need to be mindful of the selenium concentration in their area, as otherwise they could easily and unknowingly be poisoning their horses. The different forms of selenium toxicity include acute and chronic toxic conditions.

FormDescriptionClinical signs
Acute (Blind staggers)Least common form. Occurs when a horse ingests a high dose of selenium over a short period of time (greater than 500 to 1000 ppm). Blindness
Respiratory failure
Kidney failure
Colic signs
Chronic (Alkali or bobtail disease)Most common form of Se toxicity seen in horses. Horses must ingest a minimum of 3.3 mg/kg of body weight of Se daily. Lameness
Hoof soreness
Reddening & swelling of coronary band
Hoof crack parallel to & below the coronary band
Poor hoof quality
Rough haircoat
Hair loss

Symptoms

Hair loss
Dull coat
Cracking, brittle hooves
Bone lesions
Ataxia
Increased heart rate
Depression
Diarrhea
Fever
Weakness
Respiratory distress
Nervousness

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Laboratory tests

Treatment


TreatmentDetails
Diet managementChronic Se toxicity can sometimes be helped by switching the horse to a low Se, high protein, high quality diet
Supportive careProviding proper hoof care to help minimize pain or turnout on soft, sandy footing

Prevention

  • Monitor pastures
  • Perform soil tests

Scientific Research References

Good Overviews

  •  icon
  •  icon