Puppies with less than 28 teeth and those that they have are sharp and thin are 8 weeks old or younger. Adult dogs have 42 teeth once they are fully grown. Puppies lose their teeth at around 3 to 7 months of age, when their adult teeth start to come in. After 7 months of age, estimating a dog’s age becomes more subjective. Small breeds may develop periodontal disease as early as one year of age. Dogs differ in how quickly they gray, but it’s rarely seen in young adults. Age-related graying is typically most noticeable on a pup’s muzzle, around their eyes, and on their paws.
As dogs age, the nerves in their eardrums can break down, making it harder for them to hear. If you notice that your dog is surprised when you come up from behind or doesn’t bark at the door anymore, it may be a sign of hearing loss and aging. Arthritis pain is a common cause of “slowing down” in senior dogs. Many senior dogs are prone to changes in their sleep cycles. They may sleep most of the day, then pace and experience anxiety at night.