I ran across the name Thietshoorn while looking at my cd of New York Births & Baptisms. This was for a Rebekka married to Juriann Kwik (also with various spellings). In other records her name was spelled Tietsoort, Tietsoord, Titsso, and Tizzo. There may be others, but it looks like Teetshorn definitely could have started out as Tietsoort.