How can I tell the age of a Border Collie? The age of the Border Collie can be judged by the development of the teeth. 30-40 days, the milk incisors are complete; 2 months, all the milk teeth are complete, the tip is thin and tender white. 2-4 months, the first milk incisor is replaced; 5-6 months, the second and third milk incisors and all milk canine teeth are replaced. 8 months or more, all the teeth are replaced with permanent teeth. At 1 year of age, the permanent teeth are complete, shiny and firm, with cusps on the upper incisors. At age 6, the cusps of the third incisor of the lower jaw are worn out and the canine teeth are bluntly rounded; at age 7, the first incisor of the lower jaw is worn to the root of the tooth, and the wear surface is longitudinally oval. The weight is about 26-31.5kg for males and 25-27kg for females.
