Foundering from salt block

Has anyone ever heard of a horse foundering from consuming too much of a salt block. My 11 year old paint went completely lame 3 weeks ago, I thought he had sore feet but he just kept getting worse. I then suspected he might be foundering, so I put him in the barn on hay but he kept getting worse, so I put him back out to pasture and he seemed to improve. I started to think what had changed in the last 3 weeks and I remembered that he had gone threw a salt block and I got him another one that he had almost gone threw the new one. I took all the salt blocks away and he is almost better. I have always used the brown ones and never had any problems. He has never consumed that much salt before, I have had him for 10 years. The ponies have not been doing this. Anyone have any thoughts about this.

Brown/Red salt blocks have minerals added to them, it is entirely possible that he got an overt amount of those minerals and it translated to foot problems for him. Too much of a good thing can be a bad thing.

I bet if you looked up what was in the salt block, then looked up what each thing was capable of doing in too large quantities, you'd find your culprit!