Your pup had no teeth when he was born, but he quickly developed a set of 28 deciduous teeth. During the next several months, you may have noticed a stray tooth here and there, as his permanent teeth replaced his baby teeth. By 7 months, a dog should have a full set of 42 teeth.
When Beau was still a baby, he didn't need teeth right away because he was still nursing off his mother. His baby teeth didn't randomly appear, but instead followed a basic pattern. His incisors -- the small teeth in the very front of his mouth -- erupted first, followed by his canine teeth. The premolars, on the sides of his jaws, were the last of his baby teeth to show up. A puppy's teeth tend to start erupting around 3 weeks of age, giving him a full set of deciduous teeth by the time he's 8 weeks old. If everything plays out normally, he'll begin growing his permanent teeth around a month later, pushing his baby teeth out in the process.
It's not all that unusual for your puppy to smile at you with a gap-toothed grin; his baby teeth are very brittle and can easily break and fall out. However, if your dog is more than 6 months old, he should have all his permanent teeth. If he's a toy breed, it may take a bit longer for his teeth to grow in, however, if Beau's an adult, he should be sporting a full set of chompers.
There are a couple of reasons a dog might be missing a few teeth when he reaches adulthood. If Beau's missing his canine teeth, they may be congenitally absent -- they may have never developed when he was developing in the womb. The other option is he has canine teeth, but they never erupted and are still within his jawline.
If Beau is missing some permanent teeth, he should see the vet. Chances are it won't be a big deal, however, if those canines never erupted, the vet should determine if they'll cause problems later on. An unerupted permanent tooth can cause dentigerous cysts, which untreated can lead to problems with Beau's jawbone. All teeth -- the canines, incisors, premolars and molars -- can fail to erupt and it's far easier to remove the unerupted teeth than to treat the dentigerous cysts later.
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