What Is The Natural History Of Guinea Pigs?

?Originating from South America, the guinea pig was originally domesticated for food and ritualistic purposes as early as 5000 BC, and became a popular companion animal when brought to Europe in the 1600's. In many parts of South America they remain an important food staple. Their docile nature has made them ideal pets and livestock, and they have been invaluable in medical research due to many similarities to humans.

Like their wild ancestor the cavy, guinea pigs are strict herbivores, and social animals with a group hierarchy. While they are much more tame than the wild cavy, they still retain a tendency to be crepuscular (active at dawn and dusk) and need places to hide to feel secure. 

Today many breeds are recognized and shown by cavy fanciers, but the main coat varieties are smooth, Abyssinian (rosettes of fur growing in different directions), and the long haired Peruvian. Other breeds include the hairless skinny pig, the Teddy with a rough brillo coat, and the Texel with long curly waves.

What Are The Different Guinea Pig Breed Varieties?

1. Smooth coated breeds

  • Short Haired
  • American Crested (Crested, White Crested)
  • Ridgeback

2. Long coated breeds

  • Silkie/Sheltie
  • Texel
  • Peruvian
  • Alpaca
  • Coronet
  • Merino (English Merino)
  • Lunkarya
  • Sheba (Sheba Mini Yak)

3. Rough coated breeds

  • Abyssinian
  • Rex
  • Teddy

4. Hairless breeds

  • Skinny
  • Baldwin

?They all exist in a variety of colors. Adult males weigh around 1000 grams, females weigh between 700 to 850 grams. Life expectancy ranges up to 8 years with 4-6 years average. New breed classifications are appearing all the time!

How Do I Know If My Guinea Pig Is Healthy?

A healthy and happy guinea pig will have bright eyes and shiny fur, and be alert and react to its surroundings. It should be inquisitive and active. Healthy pigs have a hearty appetite and make a lot of poops!

Despite domestication, guinea pigs are considered "prey" animals, which means they are hard-wired to constantly be on the watch for predators. In the wild, it can be deadly to show weakness or illness to a potential predator, so prey species will automatically hide any infirmary. They can be in great pain and discomfort but will act normally until they absolutely cannot continue.

It's a good idea to get your pig checked by a vet once a year, especially as they age. Even if they seem fine, they may be hiding something! Many ailments start at around 3 years of age.

Some telltale signs of a sick guinea pig may include:

  • Not eating as much, or only eating certain foods
  • dropping food/interest in food but unable to eat
  • Feces misshapen, small, wet/cowpie, or few in number
  • Red, irritated or ulcerated feet
  • scratching a lot
  • Urine or feces stuck to rear
  • Excessive dandruff or visible lice

How Do I Keep My Guinea Pig Happy At Home?

Guinea pigs are social animals and fully capable of bonding with their owners. But, as an owner, it is important to understand the world through the eyes of an animal that is wired to be on guard for danger at all times. To a guinea pig, you're a potential predator! It can take a lot of time and effort to get your guinea pig to trust you. Like dogs, every guinea pig is different-some stay nervous their whole lives, and some are placid from birth. The more you work with your cavy, the more comfortable it will be around you, and the deeper your bond will be.

Spend some time every day quietly hanging out near your guinea pig's cage, and getting it used to your presence. Put your hand in the cage, limp, and let her approach on her own terms. Speak to her softly. Once she becomes accustomed to your presence, you can try to pet her gently with one finger on the head or under the chin. 

When handling, approach your guinea pig slowly and steadily, from the front. To lift, keep one hand under the chest and the other under the rear end, so that the whole body is supported. Hold her against your body. This way she feels secure and will struggle less. 

Spend time each day with your pig on your lap! This is good bonding time, and your guinea pig will become more relaxed around you the more you handle her. Feeding her a favorite green while you sit keeps your pig busy and happy. Another tactic for shy guinea pigs is to get down on the floor with her at face level to interact, so you're less big and threatening. 

Can I Have More Than One Guinea Pig?

As the owner, you will be a source of companionship for your GP. However, Guinea pigs are extremely social animals, and it is highly recommended to keep at least two together. In some European countries, it is actually illegal to keep a guinea pig singly. Most guinea pigs get along well after introduction, although it can be more challenging to keep two boars (males) together than females. Patience, and providing adequate space, are key. Obviously, guinea pigs of the opposite sex should not be housed together unless one or both are spayed or neutered.

Rescues and shelters everywhere are in need of homes for guinea pigs, so finding your pig a friend should not be difficult! Taking any new pig to a vet for sexing confirmation and a checkup is a good idea.

Introduction should be done after a quarantine period of several weeks to make sure that the new pig is not incubating an illness. After this period, an introduction may be done on neutral ground, such as the floor, a bathtub, or other space where neither pig has left any scent. Greens can be offered as a distraction. Taking the pigs on a car ride together can be a good bonding experience, as they will seek comfort from each other in an unfamiliar situation. Several sessions may be needed before they accept each other.

If they are compatible, clean the cage they will share thoroughly before putting them back, so the pig that was previously there does not consider it her "territory". Make sure there are many hides so that they do not fight over a favorite pigloo or box. Chasing, "rumblestrutting", mounting, nips and lifting heads high are all normal behaviors. All-out fighting is not. Guinea pigs in a fight can bite hard and fast, so separate any fighting guinea pigs while wearing gloves, or by spraying water on them. Never stick your hand in the middle of a guinea pig fight!

What Do Guinea Pigs Eat?

The daily guinea pig diet should consist of:

  • Unlimited hay
  • 1/8 to 1/4 cup pellets (with no additives such as seeds or fruit)
  • Pig-healthy greens such as romaine lettuce and flat parsley (see pyramid)
  • Vitamin C in tablet or biscuit form

The most important part of the guinea pig diet is hay. Timothy hay is the most commonly fed hay, and is widely available, but meadow hay or brome grass can be used as the main hay or as a supplement. Cavies should have access to all the hay they care to eat, 24/7.

Guinea pigs should also have pellets specifically formulated for guinea pigs, not for rabbits or other animals. Many brands include things like seeds and dried fruit as an "extra"-don't fall for this! Dried fruit and seeds are not good for guinea pigs (or rabbits or most animals) and promote everything from obesity to tooth problems. Plain timothy pellets are best, about 1/8 to 1/4 a cup daily depending on the pet's needs.

Alfalfa hay or pellets are not appropriate for an adult guinea pig who is not pregnant. Alfalfa contains too much calcium for an adult, which leads to bladder stones. Babies under 6 months and pregnant/lactating females can be fed alfalfa. 

Fresh greens are an important daily part of your guinea pig's feeding routine. Romaine lettuce, red or green leaf lettuce, flat parsley, cilantro, and a host of other leafy greens are great for guinea pigs. However, many of the greens that are good for humans are not-so-good for cavies: kale, spinach, collard greens, chard, and other high oxalate greens promote bladder and kidney stones. See the illnesses section for more information on this common problem.

Vegetables such as peppers and cucumbers are not recommended because they can cause gas in the digestive tract, which is painful and can cause the tract to slow down or stop. Avoid fruits as well, since they can cause gas and are high in sugars. Don't feed seeds or nuts of any kind. Store bought treats usually contain yogurt, seeds, or other unhealthy things, so stay away from them completely-give a baby carrot a few times a week instead. 

Water should be available at all times. Pigs drink readily from a sipper bottle, but remove and clean it daily. The sipper can get clogged, and a guinea pig can die quickly without water. A heavy crock of water can be offered but has to be cleaned several times daily. 

Why Is Vitamin C So Important For Guinea Pigs?

Guinea pigs cannot produce their own vitamin C, so they require it in their diets. Guinea pig pellets and greens provide some of this, but what we've found is that even guinea pigs with excellent diets can come down with vitamin C deficiency. Therefore we strongly recommend a daily supplement of 100mg of vitamin C. 

There are several options for this. You can quarter a human's 500mg tablet of vitamin C and give a quarter tablet daily, and many pigs take it as if it is a treat. Oxbow makes a vitamin C biscuit specifically for guinea pigs.

DON'T: Use vitamin C drops that go into the water bottle. It degrades very quickly and there is no way to monitor how much a guinea pig gets. It is a useless product.

How Do I Handle My Guinea Pig Safely?

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.

What Kind Of Housing Does My Guinea Pig Need?

Guinea pigs are active, sociable animals that love to run and explore. The bad news is that the majority of store bought guinea pig cages are not big enough for one guinea pig to exercise these behaviors-let alone more than one! They will do in a pinch, but for the long term and a happy, healthy guinea pig, you will want to have a much bigger enclosure.

The good news is that you can make a much more suitable guinea pig cage for much less than buying one at the pet store, or even buy a pre-made one online. Many people make their own for less than $25 using sign material and wire shelving. The website www.cavycages.com is an excellent resource on how to make or buy a guinea pig cage, or search "C & C cage" for more options.

The best bet for lining the cage are fleece or towels, changed daily to several times a week. It increases the laundry load, but overall it is less work, less cost and is the most comfortable for your pig than particulate bedding. Many pigs will tend to concentrate their waste in a certain area, so using a puppy wee pad in that area can cut down on cleaning.

Paper bedding like Carefresh is also great! Stay away from perfumed or scented bedding. Wood chips are not ideal, as they cause respiratory issues over time, but if there is no other option choose aspen over pine. 

Cedar chips should NEVER be used. They are especially bad for the lungs and respiratory system.

Hiding places are essential for guineas. Since they are prey animals, available hiding places make them feel secure, even if there aren't any "predators" around. Options are as limitless as your imagination: store bought "pigloos" and other structures, and things like plastic children's step stools, doll beds, and large cardboard tubes can add variety. Many pigs enjoy fleece snuggle bags and animal beds as well. There should be at least one house, "pigloo", snuggle bag, or other hiding place per pig so they do not fight over hides.

What Kind Of Exercise & Enrichment Do Guinea Pigs Enjoy?

Ideally, GP's should have at least an hour outside of their cage a day, in a pig-safe area where they can explore and stretch their legs. Make sure there isn't anything for them to chew (like electrical chords) or anything they can get behind or under (like the TV stand or behind the fridge!). Set out some things for them to explore and hide, like cardboard boxes. Some guinea pigs enjoy throwing toys like twig balls and stuffed animals around.

Enrichment refers to objects, activities and socialization that keep an animal's mind and body occupied. Guinea pigs can get bored! Varying the routine and trying new things will keep your pig happy. You can even train your pig to do tricks.

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.

How Do Guinea Pigs Reproduce?

Guinea pigs breed readily and from a young age. Female guinea pigs can become sexually mature as early as four weeks. However, the pelvic bones of an unbred female will fuse between 9 and 12 months, so a pregnant pig older than that will likely require a C-section to deliver and survive. The mortality rate for pregnant female guinea pigs is very high and pregnancy should be avoided.

Unfortunately, many pet store guinea pigs are improperly sexed, leading to surprise litters. The best way to avoid this is to get your guinea pigs seen and sexed by a veterinarian as soon as they are acquired, or to adopt from a rescue or shelter. Many people see guinea pigs as disposable, a "cheap" and "easy" pet that is acquired for children who may lose interest. The result is that rescues and shelters are inundated with unwanted guinea pigs. Please consider adoption when you are thinking about adding any pet to your family! Thanks to the internet and websites like Petfinder, it's never been easier to find a companion pet of any species. 

Gestation for guinea pigs is 60-70 days, and females who can pass the babies do not need help giving birth. The babies look like miniature versions of the adult-fully furred, eyes open, and able to eat solid food. Given the opportunity, they nurse for 2-3 weeks after birth while also eating solid food. The mother can conceive an hour after giving birth, so keep adult males and females separated. At 3-4 weeks they become sexually mature and require separation from the opposite sex.

It is important to start handling the babies soon after birth, to get them acclimated to humans and establish bonds. The mother will not "reject" them if you touch them.

What Are Some Important Medical Concerns For Guinea Pigs?

Gastrointestinal Upset: Guinea pigs eat constantly, and they poop constantly. That's a good thing! A guinea pig's digestive system is built to handle a constant influx of food, but it can be a fragile system. If that digestive flow is disrupted or stops (a condition called GI stasis), the GP can experience anything from gas discomfort to death. 

A change in appetite or feces is serious! A GP that has not eaten or pooped in 6-8 hours is considered an emergency case. A disruption in the GI tract is almost always secondary to another issue, like dental problems or lack of vitamin C. Additionally, some foods can produce gas in a GP, which can be so painful they stop eating or moving. We do not recommend feeding vegetables like peppers for this reason. Other things to watch out for include small or misshapen feces, or diarrhea.

This condition requires intervention by a veterinarian as soon as possible, since it can snowball very quickly. 

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 within 24 hours with no previous signs of illness. Conditions 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: Infections of the respiratory tract are common in guinea pigs, and usually present as sneezing, lethargy, or heavy breathing. Baby guinea pigs are especially susceptible to pneumonia. Keep pigs out of drafts and dampness and away from smoke, strong scents, and wood chips. 

Heart Disease: Like humans, guinea pigs can suffer from heart disease, and usually start showing signs around 3 years. Signs may include lethargy and sneezing, and may resemble a respiratory infection. Heart disease can be diagnosed with an x-ray or ultrasound, and is manageable with medication and regular checkups.

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. For example, very dilute urine is clear, whereas 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.

Bladder Stones: Bladder stones are common in older GP's, especially ones that have been fed a diet high in calcium and oxalates. Depending on the size and position of the stone, it may require surgery and/or oral medications to dissolve the stone. These stones are very painful and can cause decrease in appetite, decreased movement, lethargy, or sitting with a hunched posture. There may be blood present in the urine, or the pig may squeal when urinating or defecating. 

To prevent stones, avoid feeding calcium- and oxalate- rich foods like kale, spinach, and alfalfa hay. 

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.


A baby Skinny pig with ringworm

Scratching: Some scratching is a normal function of grooming; however, if the places being scratched are becoming red, irritated, raw or the GP is losing its hair, then the scratching is excessive. Your guinea pig may have skin mites, fleas, a bacterial infection or a fungus, such as ringworm. Pine or cedar bedding can cause irritation and allergic type reactions of the skin leading to redness and itching. Skin infections due to fungus (ringworm) usually appear as scabby, scaly skin lesions around the face and may involve other parts of the body. A diagnosis is made by a special culture and treatment is specific for this disease.

There are two main external parasites found on guinea pigs: lice and mites. Lice are usually visible to the naked eye and can be seen moving around the eyes, ears, and rump. They are species specific, meaning they only occur on guinea pigs. Humans and other pets cannot contract them. Mites are not visible without a microscope, and can be definitively diagnosed with a skin scrape at your vet. 

Guinea pigs can contract these parasites from the mother, from other guinea pigs they may have been housed with, or even from hitchhikers on supplies from the pet store, and they can go unnoticed for a long time. An outbreak of parasites is often secondary to another issue. Because a sick guinea pig will not groom as much, a small population of parasites can quickly explode into an infestation. Consult with your veterinarian for selection of appropriate treatment.

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, 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). More info on vitamin C in guinea pigs click here. Signs of arthritis include decreased movement, limping or dragging back legs, dirty rump, red feet, or general sensitivity to touch. Arthritis is not reversible but, like humans, it can be managed with daily oral painkillers. Proper diet is key for prevention.

Pododermatitis, aka "Bumblefoot": Sometimes a guinea pig will develop redness or sores on the bottom of the feet. This can be from standing on hard surfaces (like plastic cage bottoms), but it is usually secondary to another problem. It indicates that the GP has not been feeling well, and standing in one place for extended periods. It is not uncommon for these foot sores to swell and become infected. This is a very common sign of illness, so inspect your pig's feet regularly and see a vet if they appear red or ulcerated. 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 lose weight and become seriously debilitated in a short time. Any illness, Vitamin C deficiency and overgrown teeth can cause a GP not to eat.

Lumps And Bumps: Older intact females can develop ovarian cysts. Signs of cysts include symmetrical hair loss along the sides and swollen abdomen. Treatment for cysts varies according to the patient. 

Mammary masses can pop up on both sexes, as well as cysts and other growths anywhere along the body. An infected bite can swell into an abscess if left untreated. If you find a mass, schedule an appointment with your veterinarian. Some bumps are benign, but others require surgical intervention.


Overgrown Teeth: Guinea pigs are rodents, and a rodent's teeth never stop growing. The front teeth, the incisors, are easily visible and used for picking up and cutting food. It is the back teeth (molars) that cause the most problems. These cannot be seen without the help of your veterinarian. A normal set of teeth will be ground down through chewing, but if something goes wrong, the teeth will keep growing until the GP is unable to eat. 

The most common cause of dental disease is poor diet and lack of vitamin C, which cause the ligaments holding the teeth in place to shift. When the top and bottom teeth don't meet properly, they continue to grow without being ground down evenly. These teeth can grow into the cheek and cause painful ulcers, or more commonly the lower teeth grow over the tongue like a bridge. Eating becomes difficult or impossible, and the pig slowly starves to death.

A guinea pig with dental issues will have difficulty picking up food, suddenly refuse foods they previously enjoyed, drool, or lose weight. Watch out for swelling around the face that can indicate a dental abscess. Guinea pig dental disease can be treatable, but is not reversible and usually progresses. It may require dental work (often under anesthesia) for the remainder of the pig's life, as often as every 3 weeks.

If you have any questions, please feel free to call us at (707) 940-8748

Content provided with permission by by ?Susan Horton, DVM, and Jessica Johnson of Chicago Exotics Animal Hospital