How accurate are they?

[nbhalla19]

How accurate are vets when they estimate ages for guinea pigs? I have two guinea pigs. I have taken them to two different vets(one is close to my apartment the other is close to my parents house when I stay there sometimes). Both said the birth date of one of them is 3/1/2019. For the other one, one said the birthdate is 7/1/2020, while the other one said the birthdate is 9/1/2020. I remember I got her from the pet store the beginning of September only, like September 8th. She was around 300 grams also. So I'm assuming she was born more around July, as if she was born September she wouldn't have been that big and she wouldn't be at a pet store just yet. In general, when they determine the age they were born, I'm guessing it's an estimate overall?

 

[Piggies&buns]

A vet won’t be able to determine their date of birth - the only people who know that are the breeders.

In the UK the age of going on sale is usually around 8 weeks (doesn’t mean to say they are that age though) so you can only make a very rough guess by counting back around 8 weeks from when you got them (but they could be older than that by several weeks or indeed may have been sold younger if the rules for sale in the US are different)

 

[Wiebke]

Hi

The survivable birth weight can vary between 40-140g, which is over three times between the smallest and the largest pups. The weight difference carries through, which is why a certain weight is not necessarily a reliable indication of age, either. I would put the estimated age between June to August since you can never tell with pet shop or breeder piggies that come without a birth date.

The largest pups can weigh 300g well before they reach 3 weeks and others can be 3-4 months old at that weight if they come from the lower end of the spectrum - and that difference in weight and size usually carries on throughout the whole life.
The good news is that on your good care and diet, they will all have a perfect chance to realise their optimal weight/size ratio (BMI) and that - barring genetic or unforeseeable medical problems - gives them all a good chance of living a full life span.
Both my largest/heaviest and several of smallest piggies have lived to celebrate their 8th birthday, irrespective of their size and background whereas a number of 'average' piggies of mine died at a much younger age due to health issues but some also managed to live past the average life span of 4-7 years. You can just never tell but you can improve your piggies' chances to reach the upper end quite a lot with a good diet. In the end, it is not so much where and when they have started out but your daily good care that counts the most.
This guide here explains some of this: Weight and Weight Loss Explained: BMI, Weighing, Poos and Feeding Support

Unfortunately, with most guinea pigs we will never know the exact birth date or month. In the case of adult dumped or abandoned piggies we may even never know the birth year apart from 'younger', 'full' or 'mature' adult. A vet will go by general state and physical markers in their hands-on assessment. What counts, is the happy todays in good care that guinea pigs measure their lives by; however long or short. Birthdays and average life expectancies are entirely human concepts.

If you feel very strongly about your piggies having a birthday, then you may want to choose a suitable day within the likely birth span on which to celebrate it.

 

[nbhalla19]

Yeah I see. I remembered clearly, and the one born in 2020 I got from the pet store 9/8/2020. She probably wasn't born 9/1/2020 as she would have just been a week old and I know pet stores don't sell them that young. She was probably born around July only like the other vet said. She was probably around 300 grams only from what I remember.