Puppies enter the world essentially toothless, a lot like most human babies. The little guys quickly develop deciduous teeth, however, which are temporary additions that are necessary until their permanent chompers start growing in. Dogs are indeed supposed to have adult and baby teeth, although not usually simultaneously.
Puppies generally have some baby teeth when they're roughly a month old, and the teeth often begin emerging as early as 3 weeks old. When puppies are around 2 months old, these teeth should all be present and in good working order. Their canines appear initially, and then their incisors and molars promptly come next. They have 28 of these little pearly whites in total.
When growing puppies reach approximately 3 months old, they reach the landmark of developing their adult teeth, which are simultaneously sturdier and larger. Deciduous teeth, sometimes called milk teeth, are usually on the weak and fragile side. As these "big boy and girl" teeth prepare to make their entrances, they eject the baby teeth. If you have a puppy who is in the midst of this process, it might not be apparent to you. You might randomly encounter the odd tooth or two in your pet's bedding, but the puppies tend to swallow lose teeth as they eat.
Emergence of Teeth
After a few weeks of teeth falling out, puppies' adult teeth start becoming noticeable when they're about 4 months in age. The incisors show up earliest, and the molars, premolars and canines are next. When puppies are about 7 months old, they should have all the teeth they need -- 42 of them. The full transition from baby to adult teeth doesn't occur overnight, and often requires between three and five months.
Retained Baby Teeth
Retained baby teeth describe a condition that occasionally affects young dogs. This occurs when the adult teeth don't push the baby teeth out all the way, most often seen on the upper canines and incisors. Tiny pooches are particularly susceptible to it, including pugs. All of these teeth packed together create cramped situations in the interior of a dog's mouth, and can result in serious irregularities in the positioning of the teeth and in the jawbones' proper maturation. It can also cause food to be trapped in the mouth, which can trigger big problems including tartar accumulation, periodontal disease and halitosis. Because of all of the potential hazards of retained baby teeth, visit your vet immediately if you suspect the problem. He might need to remove the baby tooth surgically.