Epidemiology.

Toxicity is more common in dry regions and in these situations, horses can suffer from “alkali disease” in which excessive selenium causes a loss of hair on the mane and tail, lameness and bone lesions, including twisted legs in foals and sloughing of hooves (Frape., 1998). This inorganic form is more likely to cause toxicity if inadvertently fed in excess, as in when feeding multiple feeds, all of which contain selenium. One can counter high Se levels by feeding a mineral high in sulfur. Selenium Selenium intake: 0.5-2.0 mg/kg bodyweight. The recommended minimum daily intake of selenium for an average sized, idle, adult, nonbreeding horse is 1 mg/day, or 0.1 mg/kg (= 0.1 ppm) in the total diet. Proof was soon obtained that selenium was the cause of alkali disease. Lameness, loss of appetite, partial blindness, staggering and paralysis are all indicators of severe selenium poisoning. Selenium toxicosis occurred when animals consumed these plants. Magnesium is another commonly overfed mineral.
Timecourse.

The first sign of selenium toxicity is loss of mane and tail hair; in extreme cases, the hooves will slough off and the horse will have to be euthanized. Adult horses should not get more than 5mg per day. Acute toxicity can occur after a single dose, whereas chronic toxicity often develops over prolonged periods (>30 days). There is more data on the toxicity of Se in cattle and sheep, but selenosis affects all livestock. A condition called Amyotrophic Lateral Sclerosis, also called ALS or Lou Gerig's disease, is particularly linked to selenium poisoning- although any range of neurologic problems could be due to selenium toxicity. It was also shown that certain plants accumulated selenium in relatively large concentrations.


In its inorganic form, as in Selmit1 or Selmit 5 from your veterinarian, or as is found in most pre-mixed horse feeds.

All animals exposed to high selenium at risk of development of clinical signs.

Toxicity: The margin between ideal and toxic levels of selenium is very slight, and selenium toxicity can be far more dangerous than a deficiency. The 21 polo ponies that dropped dead at the U.S. Open Polo Championship in Wellington, Fla., eleven days ago most likely succumbed to an overdose of selenium, used to … A sign of selenium poisoning is the loss of hair surrounding the mane or tail. Selenium toxicity from properly formulated and manufactured supplements, grains or from hays is virtually unheard of, even if you use more than one source of selenium. What Dosages cause Selenium Overdose. Selenium is a mineral found in the soil in many areas of the country.

Horses normally ingest selenium while foraging. Symptoms of selenium poisoning include pulmonary edema, reduced blood pressure, unconsciousness and death -- which are consistent with the symptoms observed in the stricken polo horses. Above 20mg per day can cause chronic selenium poisoning. The toxicity and deficiency sections are general information and contain diseases that affect most species; for species specific diseases, see that species' section. Diagnosis

You should have your hay tested as many areas of Colorado have high soil selenium and hay grown in these areas will be high in selenium. In other areas—the Midwest for example—selenium is deficient in the soil, and without proper supplementation horses can have significant problems. intensive research was

selenium were found in some small grains grown in the area.

Selenium toxicity is a serious threat to livestock in the western United States. In selenium rich environments, the plants will absorb this metal from the soil, posing a risk to horses that graze there. During the following 15 years. The most serious toxicity symptoms are neurologic problems. Symptoms of toxicity include heart and liver damage; degeneration of bones, joints, and muscles; cracking or …