by Susan Horton, DVM
The guinea pig (GP) or cavy, Cavia porcellus, is the domesticated form of a rodent found native to the Andes Mountains of South America. In the sixteenth century they were brought to Europe and selectively bred into three main varieties. Though more recently, a multitude of new varieties have been developed through mutation of these three basic types. I will add pictures of these varieties when I can.
Here is a list of breed varieties:
1. Smooth coated breeds
- Short Haired
- American Crested (Crested, White Crested)
2. Long coated breeds
- Merino (English Merino)
- Sheba (Sheba Mini Yak)
3. Rough coated breeds
4. Hairless breeds
Pictured to the left is a skinny pig named Wilbur. These pigs are for the most part hairless except for coarse hair around the head and extremities.
Pick up your pig by grasping it firmly but gently around the chest. Hold it close to your body to provide it security. A frightened pig will wiggle and squeal until it feels secure.
Cages should be made of durable glass, plastic, of metal. Wood is not recommended, since pigs chew on wood, and it is difficult to clean. Pigs rarely jump or climb so they can be kept in open top enclosures as long as the walls are at least 10 inches high.
Floor may be wire or solid. If wire is used, the mesh size should be large enough to allow the leg to be pulled back if the foot slips through the wire. Sore feet and broken legs are more often occur in pigs kept on wire floor. An area of Plexiglas should be placed in the cage to protect feet. Solid floor is preferred but requires more effort to keep the cage sanitary.
Hay, pellets, recycled newspaper, or aspen shavings may be used as bedding. Do not use cedar or pine chips. These woods contain aromatic oils that smell good to us but are very irritating to the eyes, skin, lungs and mucous membranes of the sinus of the pig.
Pigs tend to panic when frightened so their cage should be located in a quiet spot away from excitement and noise. Ideal temperature for pigs is 65 to 79 degrees, with 40 to 70 % humidity. Pigs prefer 12 hours of light to 12 hours of darkness.
A female should not be bred until she weighs 500 g, or is 4-5 months old. Also, no female older than nine months should be bred. Between the ages of 9 and 12 months, if she is has never given birth, her hip bones (pelvis) will fuse such that she can not give birth naturally. A later pregnancy will require a cesarean section. Therefore, if you plan to breed your female, or if you do not plan to spay her and the situation is such that she may become pregnant later on, you should probably see that she has at least one litter between the ages of five and nine months.
If an older female does accidentally become pregnant with a first pregnancy, you and your veterinarian will want to plan on surgery to deliver the babies; otherwise she will likely die giving birth. In addition, do everything you can to avoid such an accident in the first place i.e. keep her away from male GPs.
The gestation period (time between conception and giving birth) for guinea pigs is approximately 60-70 days. Guinea pigs do not normally require assistance in giving birth. The babies are born with a full coat, open eyes, and can run and eat solid food. They will nurse for two or three weeks even though they are eating on their own. The young are usually in no danger from either parent, although you may want to remove the male right away, since the female is able to conceive again within the hour after giving birth.
Litter size varies from one to eight, but typically have two to four. Weaning is at 14 to 28 days, when pigs are about 200 grams. Guinea pigs become sexually mature as early as four weeks of age so it is important to separate the different sexes by then. Therefore, the males of the litter should be separated from the mother and their sisters directly after weaning.
It is important to handle the babies soon and often, to socialize them to humans. Like other animals that are born precocial, guinea pigs form their social bonds shortly after birth, sometime within a matter of hours, so human contact is critical during this time to ensure that they establish strong bonds to people.
Pregnancy Toxemia: Commonly seen in stressed, heavily pregnant GP that are 56 days or more into the pregnancy and carrying 3 or more fetuses. Acute death may occur with in 24 hours with no previous signs of illness. Condition may also present as ruffled hair coat, lethargy, loss of appetite 3-5 days prior to death. In most cases, the condition is fatal despite treatment. The cause is not known but seems to occur more often in obese pigs.
Sniffling, wheezing, sneezing, runny nose: These signs are typical of upper respiratory tract disease. Other signs include blood stained crusts around the nose, discharge from the eyes, and difficulty breathing. Common causes include bacterial infections, allergy, and irritation due to inhalation of smoke, fumes or odors from cedar/pine shavings. Do not use cedar or pine as bedding. These woods contain aromatic oils that are very irritating to the mucous membranes of the eyes, nose, throat and lungs.
Swelling around the neck: Lumps may occur around the neck caused by infection and abscess formation in the lymph nodes of the neck. This condition may or may not be painful to the pig. Treatment varies from oral medications to surgical drainage or removal depending on the extent of the infection.
Bacterial infections: May occur in the skin (sores, abscess), lungs (pneumonia), blood in urine, intestine (diarrhea), or blood (septicemia). Infections may cause depression, decreased appetite, and may rapidly progress to death. Consult your veterinarian immediately if your GP is ill. Use of medications without veterinary supervision may result in the death of your pig, as many medications used in other animals can be deadly to GPs.
Blood in urine: Bloody urine may appear red or brown. This may indicate infection of the bladder or kidneys, bladder stones or problems with the clotting ability of the blood. If your pig is female, it can indicate a problem with the uterus. Other reasons for abnormal color of the urine include muscle damage, diet, and concentration of the urine i.e. very dilute urine is clear where as very concentrated urine is dark yellow to orange in color. These changes may be normal or may indicate other disease is present. Normal urine is thick and white to yellow in color.
Diarrhea: Diarrhea can result from feeding your guinea pig a new type of vegetable, or an unusually large quantity of fresh vegetables. Try not feeding that new vegetable (or not feeding so many vegetables) for a day or so to see if the problem clears up. Whether or not his/her vegetable consumption has changed, if a day passes and your guinea pig still has diarrhea, contact your veterinarian. Diarrhea is a very serious problem. It doesn’t take long for a small animal to dehydrate. If the diarrhea begins after the GP has been on an antibiotic this can mean that the antibiotic is killing off the normal bacteria as well as the bad bacteria. Contact your veterinarian right away. In many cases, feeding live culture yogurt while your GP is on antibiotics can reduce the chance of this occurring.
Trouble walking (stiff joints or stumbling): GPs must have vitamin C in their diet. Like humans, they are not able to manufacture Vitamin C in their body. If the diet is deficient in Vitamin C, signs of scurvy rapidly develop. Lameness due to Vitamin C deficiency may be seen after only 2 weeks on a deficient diet with fast growing young and pregnant pigs being affected first. The most common signs are decreased appetite and joint pain. Always feed your GP a pelleted diet labeled for GPs. These diets are formulated with higher levels of vitamin C. Buy the pellets in small amounts (no more than your GP will eat in two to three weeks) and buy bags labeled with an expiration date or a milling date. Do not feed pellets that are older than 3 months past the milling date. Do not buy pellets from bulk bins at feed stores. This food may be old. As food ages, the Vitamin C is one of the first vitamins to be lost. Adding Vitamin C to the food is helpful. Children’s chewable vitamin C tablets can be sprinkled in your pet’s food each day (50 – 100 mg per day).
Pododermititis, sores on the feet, commonly occur in pigs kept on wire. Treatment consists of moving the pet to dry, soft bedding, and caging on solid floor. Medications selected by your veterinarian may be needed.
Loss of appetite: Being small animals, guinea pigs usually eat constantly and metabolize food very fast, so if an illness or other condition is preventing them from eating they rapidly loose weight and become seriously debilitated in a short time. Any illness, Vitamin C deficiency and overgrown teeth can cause a GP not to eat.
Overgrown Teeth: GPs’ teeth grow continuously throughout their life. If the incisors (front teeth) or molars (back teeth) are mal-occluded, i.e. they do not meet evenly, then they do not wear down when the GP chews. This results in overgrowth. Malocclusion is usually caused by a congenital deformity of the jaw. Other causes can be injury or trauma to the teeth or jaw and infection in the tooth roots. Overgrown teeth can cause mouth infections, ulceration of the inner surface of the cheeks or tongue and inability to pick up and eat food. GPs may show interest in food but seem unable to eat, drooling seen as wet fur around the mouth and neck and weight loss. Overgrown teeth need to be trimmed and periodic trimming is often needed for the life of the GP. If the molars are involved, or if the GP is very skittish, a general anesthetic may be required.