how old is my new pet?

How old is my new pet? Finding out the birthday to your new dog or cat

Have you adopted a new cat or dog recently but don’t know how old they are? Understanding the age of your new pet can help you make better decisions about their nutritional needs. But figuring out their exact, or even approximate, age can be quite difficult, especially for an older pet. Plenty of pet parents have this experience, so you are not alone.

Although your new pet’s birthday, or even birth year, may continue to be a mystery, there are several clues your veterinarian will use to make a reasonable estimate of your new pet’s age. We are sharing some of them below so you can develop a plan for your pet’s nutrition needs and health care.

For Cats

  • Cats typically grow about 1 lb. per month for the first 6 months of their life. If your new cat is clearly very young, you can put them on a scale to get a reasonable idea of how old they are. For example, if they are 4 lbs., then they’re likely around 4 months old. Once your pet is over 6 lbs., this system is no longer a reliable indicator of age.
  • If you can safely see their teeth, look for canine teeth. Those are the very large pointy ones and tend to poke through the gums around 6 months of age. These teeth will then grow slowly for the next two months. Please be gentle when looking in your cat’s mouth because, like humans, mouths are personal spaces for most animals. If your new cat is not into showing off their pearly whites, avoid pushing the issue as it may be a bit too much for your newly forming relationship!
  • After about 9 months, it becomes much harder to determine your cat’s exact age. And to make things more difficult, they all age differently. Some cats can live into their early twenties, but everyone will show their age very differently.

For Dogs

  • Puppies all gain weight differently, but most tend to reach ½ their ideal adult body weight when they are around 4 months old.
  • Larger dog breeds grow more slowly and for longer than small dog breeds. While these large breeds grow quickly during their first year of life, their growth slows considerably after their first birthday. Some giant breeds, such as Great Danes, Saint Bernards, and Mastiffs, can continue to grow until they are 24 months old.
  • Puppies lose baby teeth in a way that can also help you figure out their age. You can usually see their canine teeth poke through the surface of their gums when they are around 6 months old. These teeth continue to grow for the next few months. Very small dogs may be slightly older than 6 months when their canine teeth appear. Some dogs never lose their baby canine teeth and might have both their baby and adult canine teeth into adulthood! Just like our feline friends, dog’s mouths are very personal spaces. If your new dog doesn’t want to show you their teeth, avoid pushing the issue as it may be too stressful for them this early in your new relationship!
  • Once a dog reaches their adult size, it can be very tricky to predict their age accurately. Some clues of aging include tartar buildup on their teeth, graying hair around their muzzles and ears, and cloudiness appearing in their eyes. Every pet is different though and will show these characteristics at their own unique pace. If you see these signs, you can guess your dog is more than 3 years old.
  • Larger or giant breed dogs tend to age more rapidly than smaller dogs, and they will show signs of aging much sooner than the smaller breeds.


If you think your pet is a youngster, you’ll want to consider choosing a food designed for this important growing stage of life. Use the guidelines on your pet food packaging to get an idea of the amount you should be feeding. As you become more familiar with your new pet’s unique metabolic needs, chat with your veterinarian or our nutrition team to help further fine-tune their diet.


Still have questions?

Our pet nutrition team is here for you. Send us an email, give us a call or connect with us through LiveChat. We’d love to talk through your pet’s unique nutritional needs!