it doesn't - and shouldn't - apply because horses are vegetarian and their poo is neither smelly nor dangerous to people, unlike dog poo.
You took the words from my mouth. Thanks, NBT.
Incidentally, if anyone wants some free well-rotted horse poo for their rhubarb and roses you'll be welcome at Hargate Hill Equestrian Centre at Charlesworth. With around a hundred assorted riding school horses and ponies and horses and ponies at livery there is an amazing amount of the stuff! Just go up there in the daytime 7 days a week and speak to a member of staff