From my research, I believe Perigo may be a converso name, taken by Jews who converted to Christianity after the inquisition. Similarly: Duran/Durango, Far/Fargo (as in Wells Fargo). The original Perigo name would have been Peres or Perez, meaning rock.
Incidentally, did you know Elizabeth Taylor is a Perrigo? Her grandfather was named Jonathan Perrigo, and is described as Italian, but when did you ever meet an Italian named Jonathan?