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:

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 the piggies don’t appear full grown, then we assume 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 4-7 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"!

Don't All Male Guinea Pigs Fight?

     There are many misconceptions on the Internet and in books. The most common one, I think, is that all male guinea pigs fight.  We have adopters coming to us all the time insisting they want females because they've read all males fight. It simply isn't true.

    The books are partly right but they aren't telling the whole picture. Some males do fight, and some females fight. We've had over 500 guinea pigs come into our rescue and the meanest one we ever had was a female named Smudge. She didn't get along with anyone. Some males were afraid of her as soon as they met her. We had 3 males who saw her and they ran immediately to the far corner of the cage away from her and cowered. She was a tough opponent for those who dared to challenge her.

   It is very common for us to take in pairs of bonded males. They have been together almost their whole life and we rarely see squabbles out of them. They are often gentle souls who would make great pets. Of the 5 friendliest piggies we've had here, 4 were males. People who overlook males because of what they've read are missing real treasures. 

    Here's a few links to guinea pig owner's experiences with male piggies. The links are all from, a great resource about piggies.:

Boars Living Together

Boars,& Potential Impaction Problems

Boars Behaving Badly

Boars Behaving Better

Pet Store Merchandise:

Exercise balls are very bad for guinea pig's backs, as are wheels.

Many of the brands of feed at pet stores are not good for your guinea pigs.

Food and treats with seeds, colored bits etc are bad for your piggy.

Pet store cages are not big enough and over-priced.

Multiple vitamins are bad for your piggy.


Don't Overlook Older Guinea Pigs

Many people assume that pups (baby guinea pigs) will be the friendliest and make the best pets. Pups are very cute and very active. Since they are prey animals, they are born with the instinct to run from people.  Older guinea pigs may not have as long to live as young pups but there are some wonderful, gentle souls in the elder group who are great companions and very charming. Many have great personalities. They are definitely worth your consideration. They are usually our favorites!

Seen in a recent Craigslist ad:

Do NOT do this!