There are four variations of Colmillos based on HP levels, ranging from 800, 1000, 1200 and 3000.
As wolves, Colmillos run very fast and are able to chase down Leon. Their main attack is to pounce and try to rip out Leon's jugular vein. This attack does massive damage and the player has to shake the control stick to throw them off. They sometimes pause and growl before attacking giving the player a chance to attack or flee. They also may spawn Plaga like whips from their bodies. They can use these whips to attack the player.
The TMP and the shotgun are effective in dispatching Colmillos when they swarm or are close. The rifle can be used to attack or see the Colmillos at a distance, for the frequent lightning will illuminate their outline.
Incendiary Grenades will kill them instantly. Colmillos can also be killed if they run into the flames. If the plaga is exposed, a Flash Grenade will kill them.
The first Colmillos at the lake can be skipped, as fighting them only yields their random drops and gives access back to the swamp, where Villagers and few items are awaiting.
If you engage the first Colmillos, you can return to the motorboat and use the harpoons to attack them. This will conserve ammo and prevent you from receiving any damage.
The Colmillos outside the Church can be ran past. These will despawn after returning with Ashley.
Colmillos will stay still and won't attack Leon if Leon stands backing them, except if they have their plagas exposed, the tentacles could attack Leon if he is very close. You can take advantage of this behavior in case you are flanked from front and back side, just stand still and ignore the Colmillos behind by dispatching the front one first, then turn around to dispatch the back one. If the back Colmillos exposes their plagas, just walk or run forward a bit to keep the distance. This strategy is very useful in Maze Garden level where ambushes from behind are common.