Weighing between 6 and 12 kilograms (some males can weigh up to 15 kilograms), the lowland paca is a large rodent, and second only to the capybara in terms of size. The lowland paca measures up to 70 centimeters long. It has hard, bristly fur, varying between red and dark grey in colour, always with white spots on the sides of the body. The front legs have four digits while the rear legs have five toes, all equipped with sharp nails. Lowland pacas have large front teeth, a trademark of rodents. They achieve high speeds when running due to their muscular hind legs.