Welcome to the forum!
Knowing situation in Russia I'm not surprised. I feel very sorry for the pony as well as for you (as there are no resources there really to help). The pony definitely needs professional help and learning yourself while not impossible is quite hard, especially with such tough case. I'd give it a try, but there is a possibility you'll have to put him down (sorry if it sounds harsh).
Here are some resources, however most are in English... :(
Bare Foot Horse --> here we go with russian version! :) Старый Друг - Здоровье и содержание
Iron Free Hoof