An Australian Cattle Dog in good condition weighs around 18–25 kilograms (40–55 lb). Both red dogs and blue dogs are born white (except for any solid-coloured body or face markings) and the red or black hairs show from around 4-weeks of age as they grow and mature. This is not merle colouration (a speckled effect that has associated health issues), but rather the result of the ticking gene. A number of breeds show ticking, which is the presence of colour through white areas, though the overall effect depends on other genes that will modify the size, shape and density of the ticking. A number of breeds show ticking, which is the presence of colour through white areas, though the overall effect depends on other genes that will modify the size, shape and density of the ticking.