Collagen dressings are meant for wounds with minimal to heavy exudates and also partial- and full-thickness wounds. They stimulate new tissue growth and help to heal necrotic wounds, skin grafts and second-degree burns. Most collagen dressings have antimicrobial agents incorporated to limit spread of infections. Collagen dressings speed up the recovery period due to the growth of new collagen at the wound site. Dressing change frequency varies from daily to every seven days. Available as gels, pastes, powders and freeze-dried sheets and derived from animal sources such as bovine, equine and porcine.