We do a lot of boar hunting with Cattahaula dogs, and we have tried many knives and spears. In our experience, spears are not very good. Once the dogs grab the boar you go in from 4 o'clock and stab behind the shoulder. Our favorite knife has a 9 inch blade 1/4" thick with a clip point and razor sharp. Handguard is a must 'cause blood makes the handle slippery and you could cut your fingers.