Pregnancy, Mites, Guesstimating Ages and other miscellaneous information:

This is a page of miscellaneous topics...  A lot of it is information that I've heard and am passing along. I hope it's helpful.

Pregnancy: This isn't meant to be a pregnancy guide. Just a few tidbits that might help you. We don't recommend breeding - there are plenty of guinea pigs needing homes. Guinea pigs are pregnant 63-70 days (I've seen other ranges quoted too).  Many unknowing guinea pig owners who recently bought 2 guinea pigs from a pet store that they thought were both males (or both females) wake up one morning to find a litter of pups that they weren't expecting.  What's even worse, their new mom is now pregnant again because she comes into heat within hours of giving birth and the father is still in the cage with her. This happens all the time. Pet stores are notorious for mis-sexing guinea pigs. The pups are born fully developed and ready to roll. They have a full body of fur, eyes open, ready to walk within a couple hours.  They usually start eating the food within a few days. Most pups are weaned by 3 weeks of age. The male pups especially need to be weaned by this age because it's not long after that that they become fertile - not often by this age but it is possible. We've been able to palpate pregnancies as early as 5-6 weeks. 

Mites: You can't see mites but if your guinea pig starts scratching and biting and has some patches of hair loss, chances are it has mites. A very large percentage of the guinea pigs we bring in from the shelters have mites. It seems that many owners dump their guinea pigs rather than get it treated. This is a shame, because it's so easy to treat. It is easily treated with Ivermectin or Revolution. It can be treated topically with a few drops behind the ear.  Ask your vet for advice - but it is very treatable. For more information on mites, see:

http://www.guinealynx.info/mites.html

They even give you instructions for treating it yourself. I always recommend going to your vet, especially the first time your guinea pig may have it. 

Guesstimating ages: Guinea pig's teeth grow their entire lives. So you can't estimate their ages by their teeth. Even our vets can only give a "best guess". If the guinea pig has developed arthritic joints, the vet can say that they are probably 4 years or older. I heard one person on a guinea pig forum say that guinea pig's nails tend to thicken as they get older and could be used a guide but our vet had never heard of doing something like that - and he's a respected exotic vet. If they aren't full grown, then we know they're less than a year. The guinea pig's life span can range from 5-9 years with good care, although one of our other vets said it's more like 4-5-6 years. As they age, they can tend to lose a little condition and can help a vet say they're "older adults". But it's a guessing game. We try to relay all the information we have about our guinea pigs to give you our best guess, but it in most cases (unless they were born here), it is our best guess. Even the information that owners list about the guinea pigs when they surrender them at a shelter is unreliable. Many of these people weren't the most attentive owners and don't remember. We had one surrender card say that "We've had the guinea pig for 5 years and he's 4 years old"!