Guinea Pig Pregnancy Calculator — Due Date

A guinea pig carries for roughly 59 to 72 days, averaging about 65. That is extraordinarily long for a rodent of its size, since mice gestate in 19 to 21 days and rats in 21 to 23, and it reflects the hystricomorph pattern of producing few, highly developed young. Pups are precocial: born fully furred with open eyes and erupted teeth, able to walk within an hour and to nibble solids within days. Litters run from 1 to 6, with 2 to 4 typical, and pup birth weight scales inversely with litter size, from roughly 60 to 80 grams in large litters up to 90 to 115 grams for singletons or twins. A sow may gain a substantial fraction of her own body weight over the pregnancy, which is why this calculator estimates weight gain at around 100 grams per pup. Two species-specific constraints govern breeding decisions. First, the guinea pig has no functional ability to synthesise vitamin C, so requirements rise from roughly 10 to 25 mg per day at maintenance to 30 to 50 mg during pregnancy, and deficiency causes serious obstetric problems. Second, the pubic symphysis must separate for the pups to pass, a relaxin-mediated widening that becomes unreliable if a sow is bred for the first time after about seven to eight months of age, by which point the joint has typically fused and dystocia risk becomes severe. Pregnancy toxemia is the leading cause of death, concentrated in the last two weeks and the first week after delivery, with obesity, fasting and stress as triggers. Sows also come into a fertile postpartum oestrus within hours of giving birth, so boars must be separated before delivery.

Cavia porcellus was domesticated in the Andes from wild cavies, with archaeological evidence of managed populations in Peru and surrounding highlands by roughly 5000 BC. It was kept primarily as a food animal, and also held a place in Andean ritual and folk medicine that it retains today. Spanish and Dutch traders carried the animal to Europe during the sixteenth century, where it became a curiosity and then a pet rather than food, and it acquired the misleading English name that references neither Guinea nor pigs. Its reproductive biology is unusually well documented because of a second career as a laboratory animal. Guinea pigs were adopted heavily by nineteenth-century bacteriologists, including work in the laboratories of Pasteur and Koch, which is where the phrase for an experimental subject originates. The decisive discovery for pregnancy management came in 1907, when the Norwegian researchers Axel Holst and Theodor Frolich showed that guinea pigs fed a restricted diet developed scurvy, giving science its first non-primate model of the disease and eventually revealing that the species shares with humans a genetic inability to make ascorbic acid. That finding is the reason vitamin C supplementation sits at the centre of modern pregnant-sow care. Twentieth-century laboratory colonies, maintained with exact mating records, produced the gestation range and pup weight data used today, and the fusion of the pubic symphysis in older maiden sows was characterised through the same colony work.