Here is Australia it is cheap and easy to keep horses living outside in yards and/or paddocks 24/7. Most of the country has relatively mild winters (only small pockets of the country actually get snow) and a few good waterproof rugs is generally all you need for winter.
So, I have not been exposed to the delights and pitfalls of the stabled horse. There is a lot about managing the stabled horse that I have no clue about or have never heard of. One of those things is Equine Canker.
I was googling for some pictures of frogs for an upcoming post and came across this canker business. I thought canker was just an old English word for cancer. And apparently that is sort of what it is - hoof cancer. The pictures I saw were grotesque. I'll post a few at the end of this post.
Here is a link to an Aussie PDF info page about canker:
The short of it is that canker is an eventual result of infected feetsies standing around in excrement for too long. It is an over growth of hoof tissues and apparently smells pretty disgusting due to the overactive cells getting infected with all sorts of vile and disgusting microbes. Yummo.
It is treatable but is degenerative and needs to be sorted out pretty early apparently.
I have never even heard of this. So there you go.