Max is no longer the tiny puppy you brought home. He looks like a grown dog, but still acts like a playful pup. Max's age isn't the only thing determining whether he's now an adult. His size plays an important role, too.
There is no magic age when Max has crossed the threshold from puppy to adult. Since smaller dogs develop faster than larger dogs, a tiny Shih Tzu will reach full size before a massive Great Dane. Grown-up size doesn't necessarily equate to grown-up manners. He'll act puppy-ish even when he's full size until he's about 2 years old. Having a big lab with the mentality of a puppy can be trying, but patience and training will turn Max into a well-behaved adult.
Depending on Max's breed, it can take 1 to 2 years for him to be full-grown. Breeds that weigh less than 30 pounds reach adulthood between 10 to 12 months old. You'll have to wait a year to 16 months if Max weighs between 30 to 80 pounds. If Max is going to weigh in over 80 pounds, he'll take up to 2 years for him to be considered an adult. If Max is a mixed breed, speak with vet to figure out how long it will take for him to reach his adult size.
As an adult Max will graduate from puppy chow to adult dog food. It takes a lot of energy for your puppy to grow, so puppy chow has more calories to meet his demands. If Max chows down on the same food he did as a pup, he'll pack on the pounds. When Max is grown, look for a high-quality food designed for adult dogs. Even if you use the same brand, switching food too quickly can cause tummy upset. To make sure Max doesn't upchuck supper, take your time with the switch. On the first day, fill his bowl with 75 percent puppy food and 25 percent adult food. The next day mix the foods 50/50. On day 3, you can give him 25 percent puppy chow and 75 percent adult. By day 4, he should be able to stomach a bowl full of his new food.
You did a good deed when you rescued Max from the shelter, but now you have no idea how old your new pal is. Take a peek at his teeth to see if he's got full-grown canines. If he's got adult teeth, it's a good indication he's full-grown. Yellowing on his back teeth means he's between 1 and 2 years old. A female dog with nipples is at least 6 months old. Max has got some growing to do if his ears and feet are large compared to the rest of his body. Max's vet should be able to give you a good idea how old he is.