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Home > Guinea Pigs > How to Figure Out How Old Your Guinea Pig Is (Life Stages Guide)

How to Figure Out How Old Your Guinea Pig Is (Life Stages Guide)

guinea pig and its babies

Guinea pigs are fun little animals that are easier to take care of than cats and dogs, which makes them excellent pet choices for younger kids who are just learning about pet care responsibility. But unless you purchase your guinea pig directly from a breeder who knows the animal’s exact birthday, you will have to do a bit of investigative work to get an idea of their age. Luckily, your guinea pig will show signs of their age as time goes on.

Here is a guide to the guinea pig’s life stages and the signs of age that are typically displayed during each stage.


What to Watch for When Determining Your Guinea Pigs Age

1 to 11 Months

Guinea pigs tend to grow quickly during their first year of life. You should notice a difference in their body size with each passing month. Their growth will dramatically slow down once they reach about a year old. Young guinea pigs also have pointy, translucent nails during their first year of life. After that, their nails begin to get thick and yellow. Young guinea pigs also tend to have small, white teeth that start growing shortly after they are born.

The teeth will stay sharp, thin, and white throughout their first year. Healthy guinea pigs weigh about 18 ounces at around 3 months of age. By the time they turn a year old, they should weigh between 30 and 40 ounces. The back ends of guinea pigs are also thin as youngsters, which will change as they age.

grey guinea pigs
Image By: Pernille Westh, Shutterstock

1 Year to 5 Years

Your guinea pig will go through more subtle changes during their adult years than when they are young. Therefore, it can be tough to tell the age of an adult guinea pig. However, there are a few signs that your guinea pig will display that can help you narrow down their age. For instance, a guinea pig’s teeth will become duller as they age. The duller the teeth are, the closer they likely are to 5 years of age.

The teeth of a guinea pig nearing their senior years may start to chip or break. Also, their nails will get more yellow and brittle with every passing year. Guinea pigs that are 1 to 3 years of age typically have better muscle tone than those that are 4 or 5 years old. These animals usually stop gaining weight by the time they are 2 years old.

guinea pig
Image By: Pezibear, Pixabay

5 Years to 7 Years

These are considered the senior years of a guinea pig. When your guinea pig becomes a senior, you will start to see their features break down. For instance, their nails will get thick and brittle and may not be as effective when it comes to playing with toys and navigating their habitats. Their backsides get wide and their movements slower. Their hair may also start to look thinner than it did in their prime.

Dalmatian guinea pig
Image By: MarketJirmann, Shutterstock

Other Ways to Tell Your Guinea Pig’s Age

The only other way to figure out the approximate age of your guinea pig is to take them to your veterinarian. The vet may be able to do testing and expert investigating via a thorough check-up to gauge the age of your pet. If anything, they can let you know whether you are catching the right signs to determine their age if you are unsure of your conclusion.



While it can be fun to try and figure out how old your guinea pig is, in the end, their age does not matter if you are taking good care of them and enjoying the time that you spend with them. So, don’t worry if you do not know exactly how old your guinea pig is. Just cherish every day that you get to spend with your beloved pet and treat them like they have an eternity to live. You will create fond memories with your pet that will last a lifetime for you, whether you spend just 3 years or a full 7 with them.

Featured Image Credit: Naomi Marcin, Shutterstock

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