I've had so much success with Magnesium chloride for my crocodile skin on the shins which has been there since I was 6 yrs old. It's a pattern of dark patches with a dry, scaly Mars-surface gridlines. They began in a small patch at 6, very light, but in the last year, they've expanded up my thighs and down to my ankles and around my legs, arms and hipjoints. No amount of oil, washing, scraping off, what-have-you worked (though my sister claims that the pumice stone was enough to exfoliate hers off, mine just got painful).
Within the first 3 applications of mag chlor, I knew they were decreasing, and now there are a few left but not as bad. I've been delighted, since they're truly a sign of some deficiency. Mag chlor seems to exfoliate while increasing the moisture content, so the skin that comes up looks younger and healthier.
Fine. Thrilled as I was, I expected it to do the same to my dogs darkened skin patches. In Icy, Magnesium chloride oil did make a huge difference leading me to believe that it does help some aging dogs, with hairfall but without skin thickening. It helped dogs in the street when I applied it - especially dogs with greying skin where the hair seems to be dropping. I was told that that was their 'winter coat shedding' - but I now believe it wasn't. It is a magnesium deficiency - something similar to the spring 'tetany' in cows, magnesium deficiency shows up most in the spring.
But in Kenchu and Gunda except for the first application, it made them highly uncomfortable, itchy and scratchy. They've got thickened skin - I think this is the major distinction is where it can be used. They didn't like Zinc Sulphate either, which those without thickened skin tolerate very well.
I still haven't tried the copper products - I have to work up the courage! Copper always makes my skin feel strange and cobwebby for a couple of days.
For Kenchu what seemed to help is Iodine applied on the skin. When I ran out of Lugol's, which he really responded to, I used Providone Iodine. It seems to work, just not as well.
He's still scaling though, so once when he really objected to an application, I applied an ayurvedic oil that was lying around. I was surprised to see him accept that well. So I was reading up on why at this site which said this,"polyunsaturated fatty acids (corn oil, linseed oil) could completely reverse the skin defects in the deficient animals, while oils containing only saturated fatty acids (coconut oil, butter) were ineffectual."
Surprising, because a lot of the ayurvedic massage oils are made in coconut oil or ghee! Anyway, I'm taking the Linus Pauling words at face value and applied linseed oil to Kenchu today. He hasn't over-reacted yet.
I also read that Selenium is a skin protective. So I've given him some Biochemic Selenium 3x to which he did react with itching for a half hour. But I will repeat it a few more times since the moon phase is LQ and ripe for the far end of the periodic table.