Basic Information Sheet: Guinea Pig

Guinea Pig (Cavia porcellus)

guinea pigs

Natural history

The guinea pig is a native of Peru, Brazil, and Argentina that was domesticated by the Inca Indians. Guinea pigs are also known as “cavies”, a term derived from the South American vernacular. Male guinea pigs are called “boars” and females are “sows”.


Class: Mammalia

Order: Rodentia

Suborder: Hystricomorpha

Family: Caviidae


Over 20 breeds of guinea pig are recognized with the three most popular being:

Peruvian: Long hair
American or English: Short hair
Abyssinian: Whorled or rough hair


Guinea pigs are strict herbivores. A sound diet consists of high-quality hay, fresh foods, and water. Offer unlimited grass hay, as guinea pigs eat small portions throughout the day. Alfalfa or clover hay should only be given to juvenile animals as the high calcium content can predispose adults to renal calcification. Fresh food can consist of grasses, herbs, leafy greens, peppers, and other vegetables. Avoid or limit fruits in the diet. Too many simple carbohydrates can lead to diarrhea and/or dysbiosis.

Guinea pigs of all ages require a dietary source of vitamin C (10-30 mg/kg per day). Fresh foods rich in vitamin C can provide sufficient levels of this nutrient. Additionally, commercial guinea pig pellets often contain vitamin C and small amounts of pellets (about ¼ cup a day) can be offered alongside hay and fresh food. Pellets should be fresh and relatively high in fiber, low in sugars and calcium, and grain free. The stability of vitamin C decreases over time and the vitamin C content of pellets is also reduced by exposure to dampness, heat, and light.


  • Guinea pigs are crepuscular.
  • Caging should be well ventilated with solid flooring. Be sure to provide visual security in the form of a hide box (one hide box per animal).
  • The enclosure size for two guinea pigs should be at least 120 x 60 x 50 cm or 50 x 24 x 20 (length x width x height). Increase the base area by at least 20% for each additional pig is necessary (1 m2 or 10 sq ft per animal is ideal).
  • Clean and change water bottles frequently.
  • Clinically normal rabbits harbor a variety of bacterial organisms that can cause death and disease in guinea pigs. Never house guinea pigs and other rodents near rabbits.
  • Guinea pigs are highly social animals that should never be housed alone. Pairs, trios, harems (1 boar and 1-10 sows) as well as single-sex groups can life together peacefully.

Normal physiologic values


Temperature 99-101.5ºF 37.2-38.6ºC
Pulse 230-380
Respiration 40-100
Body weight Adult male 900-1200 g
Adult female 700-900 g
Mean life span 6-8 y
Sexual maturity 2-4 months 2 months (F) 3 months (M)
Males will exhibit mounting behavior as early as 1 month of age.
Females can become pregnant as early as 4-5 weeks of age.
Breeding maturity Male: 3-4 months
Female: 6-8 months
Estrous cycle 16-17 d, polyestrous
Gestation 59-72 days (average 68 days)
Birth weight 45-115 g (Inversely related to litter size)
70-100 g
Litter size 1 to 13 (2 to 4 is the usual)
Weaning age 21 days (180 g)
Target environmental temperature: 65-79ºF
Avoid temperatures above 28°C (82°F)

Anatomy / physiology

Gastrointestinal Dental formula: Incisors 1/1 Canine 0/0 PM 1/1 Molar 3/3All teeth are open-rooted and show lifelong growth..
The lower incisors are normally 3X longer than the upper incisors.
Musculoskeletal: Rodents have a distinctive masseter muscle. The zygomatic arch of the skull and the dental anatomy is related to their feeding habits.

Females must be bred before 6-9 months of age. Immature male s and females have a fibrocartilaginous pelvic symphysis fusion which becomes ossified over 1 year of age. The symphysis remains cartilaginous in primiparous sows so the pelvic canal can dilate allowing passage of the large fetus.

Special Senses: Large ears with thin-walled pinnae and well-developed bullae.
Urogenital: Males have lateral scrotal swellings on each side of the anus. Accessory glands include a prostate, coagulating gland, bulbourethral gland, and seminal vesicles. Seminal vesicles are large, yellow-white tubular structures which lie dorsal to the bladder. The seminal vesicles maybe confused with the uterus.
Respiratory: All rodents are obligate nasal breathers.


Most pet guinea pigs are calm, gentle animals that rarely bite. To pick up a guinea pig, cup one hand gently under the thorax and use the other hand to support the hind end. Hold the rump lower than the rest of the body.

Large volumes: Jugular vein, cranial vena cava (only under sedation/anesthesia)
Small volumes: Cephalic vein or lateral saphenous vein

Fluid therapy

Administer warm fluids: 38-39°C (100-102°F).

Maintenance fluids are estimated as 50-75 ml/kg/day.

  • Dehydration (%) x BW (kg) x 1000 ml/L = fluid deficit (ml)
  • Correct fluid deficits over 12-24 hours

Subcutaneous (SC) fluids are indicated only for animals with a stable circulatory system and mild dehydration (max 5%).

  • Administer SC fluids up to three times per day (give one-third of calculated fluid volume at a time)
  • Infuse up to 150 ml/kg/day (average 40-60 ml/kg)

Intravenous or intraosseous fluid therapy is indicated in critical patients. Intravenous or IV catheters are placed with growing frequency in guinea pigs, but when IV catheterization fails or when veins are too small or too fragile, an intraosseous or IO catheter can be an excellent option.

Catheter type Recommended sites Comments
Intravenous catheter Cephalic or lateral saphenous vein Slow bolus: 5-10 ml/kg IV every 8 hours
Intraosseus catheter Proximal humerus, proximal tibia, proximal femur 20-22 gauge (1-1.5 inch) spinal needle
Local anesthesia with lidocaine
Use survey radiographs to confirm placement

Important medical conditions

  • Bacterial pneumonia
  • Fur mites
  • Hypovitaminosis C or scurvy (can reportedly occur within 4 days of dietary decrease)
  • Malocclusion
  • Pododermatitis

Antibiotics to avoid

Avoid antimicrobials that attack only gram-positive bacteria such as beta-lactams.

  • Penicillin
  • Lincosamide, lincomycin
  • Amoxicillin, ampicillin
  • Cephalosporins, clindamycin
  • Erythromycin


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To cite this page:

Pollock C. Basic Information sheet: Guinea pig. Feb 14, 2010. LafeberVet Web site.