If you only let the uploader assign tags, then you will run into the problem you described.
If you let everyone assign any tags to any image (multiple tags would be best), then each person will use what they want. Eventually, with enough people, every image of a pig will be tagged with all possible tags that could be used to describe it (pigs, piggy, piggie, pig, piglet, swine, hog, sow, babe, wilbur, etc.), including misspellings, and fuzzy searching will become unnecessary.