If you have an inkling that your female guinea pig may be pregnant, the only way to know for certain is by bringing her in for a veterinary appointment. However, some key behavioral and physical clues may be helpful in allowing you to make an educated guess -- at least until you get to the vet.
Gestation Period Length
The gestation period for female guinea pigs -- or sows -- typically lasts for between 59 and 73 days. Guinea pig pregnancies are lengthy compared to those of many other rodent species. If you notice any behavioral changes during the span of roughly two months, there's a good chance that your fluffy pet is indeed carrying a litter of young ones. Bigger guinea pig litters, strangely enough, tend to have briefer gestation durations.
Appetite and Thirst
One prominent behavioral change you may notice in a pregnant guinea pig is a markedly increased appetite. If she not only takes in more food, but also drinks a lot more H20 than she usually does, pregnancy is a major possibility. These appetite and thirst boosts, however, don't usually show up until several weeks into the sow's gestation -- perhaps around a month. They are not typically immediate changes.
Pregnant sows exhibit obvious weight gain during their pregnancies, but generally only during the second halves. The little ones actually make up over 50 percent of the mother's total body mass around the end of gestation. Due to this massive weight gain, you may notice key behavioral changes in the sow such as sluggishness, fatigue and reluctance to move around. Because of all of these things, mother-to-be guinea pigs may even behave in much more easily irritated manners than usual. It is important to have minimal physical contact with expectant guinea pigs.
If you observe that your female guinea pig seems to be sleeping a lot more than usual, she may just be pregnant. Non-pregnant guinea pigs that are particularly nervous and anxious, however, also sleep a lot.
Do not expect to observe any nesting behaviors right before your guinea pig gives birth. Unlike many other species of animals, sows do not establish cozy nests for their upcoming youngsters. Despite this, you may want to lend your guinea pig a helping hand toward the end of her gestation by isolating her from any other animals, and making sure that she has a tidy, calm and quiet birthing spot to welcome her babies into the world.