You almost got it right. I loved the article you posted the link to. The Pathologist used South Dakota as an example of an area of high selenium soils. I am going to give you links but the site won't let me post links until I post 3 more times. Silly rule. So I will put spaces so you can still read them. You will have to find a way to access them, but at least you will have the address.



Natural selenium in soil is taken up by plants, but is not generally from water runoff. Some States such as South Dakota and Nebraska have exceptionally high, naturally occuring, selenium in their soil. The plants we are talking about include grain producing plants that are storing selenium in the seed. Wheat, Soybean, Canola, Flax, Corn, you name it. If it grows in the soil it will uptake the selenium.
From University of Kentucky Animal Sciences Dept. They did a 3 year, 13 state study of selenium levels in Corn and Soybeans. I believe the year was 2000.



Soybeans, Canola, and Flax are high protein grains. High protein grains will store more selenium than other grains. South Dakota has a site where I read of them bragging that their bread wheat had 10.0 ppm selenium. (Like that was a good thing) This is the same place where most of the grains are grown for the western half of the United States.



In pigs 1.0 ppm in their food will cause the Chronic form of toxicity, called Selenosis. It can take less than a year for their feet to crack and fall off, the hair to fall out and have deformities in their babies, plus all the other things that go along with this toxicity. We know that .5 ppm will still cause selenosis, it just takes a little longer. We saw it happen with the pigs while we monitored the blood levels and feed levels.

Arsenilic Acid will bind selenium. Vitamin B2 (ribovlavin) will also help. This is why the Vet recomended B-Complex injections be given to the animals. It was the B2 part of the complex according to the Vet. I have seen drastic improvement, within 24 hours, in the pigs that we thought were going to die from the selenium, when given the B-Complex.
There may be a deficiency of some things, but I am thinking Selenium isn't one of them. Not unless you eat only food grown in defecient soil. In this day and age, that would be very rare indeed.
With the evidence I have, it is highly likely that there is a rash of Selenosis going on.