The story takes place in the post-apocalyptic Earth. The wild life has become extremely dangerous. A cowboy is in the clean room where he keeps the cows (maybe during the night) and sees a fly on the wall which shouldn't be there. On the next day he sees a wisp of smoke coming from an area that is presumed uninhabited. He goes to investigate on his robotic horse. Somehow his horse was damaged near the place where the smoke was seen. He had to return to his farm on foot (extremely dangerous) but his return path crosses an abandoned highway. In the middle of the highway there is another robotic horse without a master and standing there for years, presumably damaged or with dead battery. But as the hero approaches the horse wakes up and offers him help.
This may be part of a bigger text but I am not sure.
Edit - more details: I've read this story about 1994-1996. It was say 20 pages. It is possible that this was a part of longer text because at that time we had no IP laws and everybody was printing everything. It was published in Bulgarian in a small book (half size paperback 50-60 pages) with several other stories. I have a very dim memory that the author's name sounded Japanese but I am almost sure that it was translated from English.
Thank you community.