In the mid 50's, which was just 10 years after the war, the the Japanese economy was recovering, but they were no where near to where they are now, and much of the stuff they made looked a lot like the pig. As an American sailor on liberty, the Japanese bar tenders didn't like us bending or crushing our beer cans. The cans were worth money, and were cut up and turned into tin toys like your pig. I've seen toys made at that time that still had the beer brand name on the inside of the toy, so if you can see inside or under the legs, and you see part of a can label, that would date it to post war, mid 50's.