Guinea Pigs

Guinea pigs are very fun pets to have and easy to care for, but there is a lot of false information out there, especially on the internet and sometimes from pet stores, so make sure to see a veterinarian regarding proper care, caging, bedding and diet before buying all the "wrong stuff". There are only a few veterinarians in Chicago and the Chicago suburbs that specifically care for guinea pigs and other exotic pets, including the veterinarians at Midwest Bird & Exotic Animal Hospital (located near Chicago's west side, only a few blocks west of Harlem, Chicago's western border), so make sure to find the right veterinarian before your guinea pig gets sick!

Guinea Pig Facts

Scientific Name: Cavia porcellus
Life Span: 4-5 years
Environment Temperature Range: 65F-75F
Relative Humidity Range: 40-70%
Breeding Range: 3-4 Months (male) -- 3-7 months (female)
Litter Size: 1-6 range -- 3-4 average
Weaning Age: 2-3 weeks

Guinea PigThe guinea pig entered the research laboratory in the 18th century and have since made significant contributions to the scientific community. To this day, the guinea pig remains a favorite pet among children due to their docile behavior; ease of handling and clean, quiet nature.

Through selective breeding efforts, guinea pigs are found in an array of colors and coat types from which to choose. Five primary varieties are encountered in the pet industry. The Shorthair or English is characterized by having a uniformly short hair coat. The Abyssinian has whorls or rosettes in their short, rough, wiry coat. The Peruvian is recognized by its very long, silky hair. These three types are most commonly kept as pets. The Silky and Teddy Bear varieties are encountered less frequently. The Silky is a large variety distinguished by its medium length silky hair. The Teddy Bear has medium length hair of normal consistency.

Diet and Handling

What do wild guinea pigs eat?  Do they eat bowls of man-made pellets?  No. They eat fresh or dried out vegetation (also know as grass, many wild leafy greens like dandelions, and dried grasses, a.k.a. hay).  But if you are currently feeding pellets to your guinea pigs, you do not want to take them away abruptly or completely!  This can hurt them!  And when we help you to wean them down or off of the pellets, onto a healthy leafy green and veggie diet, it is of utmost importance that you wean them to an appropriate, specific diet with great variety.  Please do not guess what to feed your guinea pigs!  They can end up in the hospital, very sick, if you feed them the wrong vegetables or fruit snacks.  And if you feed them only pellets and hay, they will likely eventually get sick in different ways from eating pellets (kidney/bladder issues, gut issues, malnutrition, etc).  Tailoring a diet for your guinea pigs takes finesse and time and guidance from one of our veterinarians.  As much as we'd like to just write some easy instructions for you here, we can't risk your guinea pigs' health by assuming it's just like every other guinea pig.  They have similar diets, but not exactly the same.  We take into account your guinea pigs' age, size, urine-calcium, stools, etc, to guide you to the correct diet items and amounts.

Guinea pigs also need an external source of vitamin C, like humans do.  They can and should get it naturally by eating leafy greens that are high in vitamin C, like parsley (1/4 cup or more per day), or by eating a 1/4 of one red or orange bell pepper per day.  Please do not put vitamin C drops in the water or on their food.  Some very good pet companies sell vitamin C chewable pills, which are pretty good, but getting it naturally through their diet is far better.  Fruits are not a great source of vitamin C, contrary to popular belief, and can make your guinea pig sick.

Wild guinea pigs get lots of sunshine, even if it's through the leaves of bushes.  This stimulates their bodies to make vitamin D for them, good for their bones and bodies.  As indoor pets, our guinea pigs tend to get little to no direct sunshine.  Giving vitamin D to them via vitamins in the water or food or in any oral fashion can be toxic or insufficient, so do NOT do this!

We can help our guinea pigs to produce natural vitamin D by providing a UV-B light for a few hours, a few times a week, and by using the correct bulbs and bulb strengths.  There is still research being done regarding how many hours of light and what strengths of bulbs are best, but for now, some is better than none. 

It is important for you to schedule an appointment with one of our veterinarians to discuss your individual guinea pigs' needs.  Please don't adjust your guinea pigs' diet, bedding or lighting on your own, without instruction from one of our vets -- you could potentially harm your guinea pigs if you do not wean to a proper diet, over the proper amount of time, appropriately!!   Also, many guinea pig treats and items that are sold in pet stores are not appropriate for them-- there is no such thing as the "guinea pig diet police" to keep anyone from selling anything to you.  Buyer beware!  And please do not believe everything you read on-line!  Most of the information out there is very incorrect and/or out of date!  Please call to schedule an appointment BEFORE your guinea pig gets sick. Prevention is the best (and cheapest) medicine.

Guinea Pig

Generally, guinea pigs are docile, non-aggressive animals. They rarely bite or scratch when handled. They usually voice their protest simply by letting out a high-pitched squeal. They may, however, struggle when being picked
up or restrained. Extreme care should be taken not to injure them during handling. The guinea pig should be approached with both hands. One hand is placed under the guinea pig’s chest and abdomen, while the other
hand supports its hindquarters. Adults, and especially pregnant females, should receive careful attention and
gentle, yet firm and total support.

Housing and Breeding

Housing accommodations provided for pet guinea pigs are limited only by one’s imagination, ingenuity and budget. There is no single correct way to house your guinea pig as long as the wellbeing of your pet is considered.
Adequate housing is a major factor in the maintenance of healthy pets.

Guinea pigs can be housed within enclosures made of wire, stainless steel, durable plastic or glass. The latter
three materials are preferred since they resist corrosion. Wood should not be used due to difficulty in cleaning
and susceptibility to destructive gnawing. Ideally, the enclosure should have one side open for adequate ventilation, so be careful when using aquariums. The design and construction of the enclosure must be escape-proof. In addition, the cage must be free of sharp edges and other potential hazards. The size of the enclosure should allow for normal guinea pig activity. Approximately 100 square inches of floor area per adult guinea pig is recommended. Breeding animals should be provided 180 square inches each. The enclosure can remain opened on the top if the sides are at least 10 inches high, as long as other family pets such as dogs or cats are not a threat.

Cage flooring can be either wire or solid. Wire mesh flooring provides a cleaner environment and easier maintenance, but may result in injuries to the feet and hocks. Housing on wire over long periods of time often results in foot pad and hock infections from abrasive rubbing on fecal soiled wire. To reduce the incidence of these problems, provide
a solid platform as a resting place in one area of the cage. Broken legs are common in guinea pigs that fall through the wire mesh and panic to escape. Although solid flooring requires more effort to keep sanitary, it is safer for the guinea pig. Solid floor cages also tend to be more esthetically pleasing when appropriate bedding is used.

Bedding materials must be clean, nontoxic, absorbent, relatively dust free and easy to replace. Acceptable beddings are wood shavings, shredded paper, processed ground corncob and commercial pellets. Make sure the ground corncob is properly processed and stored to reduce fungal spore problems. Cedar shavings have been associated with causing respiratory difficulty and liver disease in some guinea pigs, so should not be used. Saw dust should
also be avoided since it tends to accumulate within the external genitalia of male guinea pigs causing an impaction.

The environment in the vicinity of the pet’s cage is another important consideration. Because of their sensitive nature, guinea pigs are more comfortable and relaxed when housed in a quiet spot away from noise, excitement
and other such stresses. Also be sure to select a location away from direct sunlight and avoid cold, damp areas. Guinea pigs thrive in a dry, cool environment with adequate ventilation. Drastic environmental changes should be prevented, especially high temperatures and humidity. Since they are nocturnal (active at night), guinea pigs
require quiet periods of light to rest.

Since guinea pigs are social creatures, more than one animal may be safely housed together. In addition, males
and females can remain in the same enclosure indefinitely. However, new males may occasionally fight if in the presence of a female. Older, dominant animals may also chew on the ears or hair of subordinate cage mates.


The single most important consideration regarding guinea pig breeding is that the female guinea pig (sow) should
be bred between four and seven months of age if she is to be bred at all. If the first breeding is delayed much beyond this time, serious and often fatal problems with delivery may result. The reason for this is that the pelvis
of the guinea pig fuses at this early age, which narrows the birth canal, preventing the babies from passing easily. Males (boars) should be at least four months of age before breeding.

The sow’s estrous cycle (“heat”) lasts 14 to 19 days. The actual period in which the sow is receptive to the boar
for breeding is approximately eight to fifteen hours during this cycle. Sows often return to “heat” within a few hours after giving birth. This time is known as “postpartum estrus”, which means that she can be nursing one litter while being pregnant with another.

Pregnancy lasts between 63 and 70 days. The gestation is shorter with larger litters, and longer with smaller litters. This duration of pregnancy is relatively long when compared to other rodents.

Pregnant sows exhibit a grossly enlarged abdomen during the later stages of pregnancy. Her body weight may actually double during pregnancy. The time of delivery is difficult to assess in guinea pigs due to the relatively long gestation period and lack of nest building by the sow. Within one week prior to delivery, a slight widening of the pelvic area can be noted. This is the separation of the pelvis, which if does not occur can cause the delivery problems mentioned previously. If the pelvis does not separate, as in sows that are bred past seven months of age, delivery of the young may be impossible without a cesarean section.

An uncomplicated delivery usually takes about one-half hour with an average of five minutes between babies.
Litter sizes range between one and six, with an average of three to four. First time litters are usually very small. Unfortunately, abortions and stillbirths are not uncommon with guinea pigs.

The young are very well developed at birth. They weigh between 50 and 100 grams and have a full hair coat.
Babies are even born with teeth and with their eyes opened. Mothers are not very maternal in the raising of the offspring in that she does not build a nest and even remains in a sitting position while nursing. The young can actually eat solid food and drink from a bowl shortly after birth, but it is recommended to allow them to nurse for three weeks before weaning.

Non-Infectious Conditions

Slobbers (Dental Malocclusion)
Slobbers is the condition where the fur under the jaw and down the neck remains wet from the constant drooling
of saliva. The primary cause for this condition is overgrowth of the guinea pig’s premolars and/or molars. Most often this occurs in older (2-3 years of age) guinea pigs and usually involves the premolars (the most forward positioned cheek teeth).

The overgrowth is due to improper alignment of the teeth when chewing, and excess selenium in the diet has also been incriminated. The overgrown tooth causes injury to the guinea pig’s tongue resulting in an inability to chew
and swallow food, drooling down the chin and neck, and weight loss (often severe). A veterinarian must be consulted as soon as this condition is suspected. The diagnosis is confirmed by visual examination of the mouth. Correction of the problem involves trimming or filing of the overgrown teeth, usually requiring general anesthesia. Dental work in the mouth of a guinea pig is difficult due to the extremely small mouth opening. A correction of the diet may also be in order if an elevated selenium level is suspected. In addition, force feedings and antibiotics may be necessary to aid in the recovery.

There is no permanent solution or correction to this problem. Periodic trimming or filing of the teeth is usually necessary. Guinea pigs with this problem should not be bred since dental malocclusion is often hereditary.

Scurvy (Vitamin C Deficiency)
As discussed in the section on DIET, guinea pigs cannot manufacture vitamin C and must receive an adequate supply from outside food sources. Lack of sufficient vitamin C in the diet results in scurvy. The symptoms of
scurvy include poor appetite, swollen, painful joints and ribs, reluctance to move, poor bone and teeth development and spontaneous bleeding, especially from the gums, into joints and in muscle. If left untreated, this disease can be fatal, especially to rapidly growing young and pregnant females. In addition, sub-clinical deficiencies often predispose animals to other diseases.

The mandatory level of vitamin C is supplemented in commercial guinea pig pelleted rations. However, with improper storage and handling these pellets lose their potency rapidly. In fact, even when properly stored in a cool, dry environment, fresh pellets lose up to half of their potency in only six weeks or so due to degradation of the vitamin. For this reason, further supplementation is recommended (see DIET section).

Contact a veterinarian at the first sign of this condition for early diagnosis and treatment. These animals must be treated early with supplemental vitamin C (given in food, water or injection) in order to reverse the symptoms.

Barbering (Hair Chewing)
Hair loss is a common problem in guinea pigs. “Barbering” is just one of the many causes of it. This vice (bad habit) occurs when guinea pigs chew on the hair coats of other guinea pigs that are lower then them in the social “pecking order”. Its normal, full hair coat identifies the dominant “pig”, and main culprit, while others have areas of alopecia (hair loss). There is no treatment for this condition except separating the guinea pigs if it becomes a serious problem.

Hair loss or hair thinning can occur for a number of other reasons as well. It is a common phenomenon among sows that are repeatedly bred or among weakened, newly bred juvenile guinea pigs. Certain fungal diseases and external parasite infestations also present with hair loss problems. These specific problems will be addressed in later sections.

Heat Stress (Stroke)
Guinea pigs are very susceptible to heat stroke, particularly those that are overweight and/or heavily furred. Environmental temperatures above 85F, high humidity (above 70%), inadequate shade and ventilation, overcrowding and other stresses are additional predisposing problems.

Signs of heat stroke include panting, slobbering, weakness, reluctance to move, convulsions and, ultimately, death. This is a treatable condition if recognized early. Heat stressed guinea pigs should be misted with cool water, bathed in cool water or have rubbing alcohol applied to its footpads. Once this first aid measure is accomplished, veterinary assistance should be sought.

Prevention of heat stroke involves providing adequate shade and proper ventilation. In addition, a cool misting of water and/or a fan operating over a container of ice can be directed toward the pet’s cage. If indoors, air conditioning during the heat of the summer provides the best relief.

Disease Conditions

Pneumonia is one of the most common bacterial diseases of the pet guinea pig. Respiratory infections are caused
by a number of viral and bacterial agents including Streptococcal pneumoniae, Bordetella bronchiseptica and a
gram-positive diplococcus. Many of the disease causing organisms inhabit the respiratory tracts of clinically normal guinea pigs.

Conditions of stress, inadequate diet and improper husbandry will often predispose a pet to an opportunistic infection with one or more of these agents. Symptoms of pneumonia may include dyspnea (difficulty breathing), discharge from the nose and eyes, lethargy and inappetance. In some cases, sudden death will occur without any of these signs.

Occasionally, middle or inner ear infections accompany respiratory disease in guinea pigs. Additional symptoms in these cases include in-coordination, torticollis (twisting of the neck), circling to one side and rolling.
Veterinary consultation should be sought when a guinea pig exhibits any of the above symptoms. A bacterial culture with antibiotic sensitivity of the throat and/or nasal discharge will assist the veterinarian in the selection of an appropriate antibiotic. Aggressive antibiotic therapy in addition to supportive care of the patient may be necessary to get the condition under control. Unfortunately, even though elimination of the symptoms is often possible with appropriate therapy, eradication of the causative bacteria is not.

Bacterial Enteritis (Intestinal Infection)
A number of bacteria are capable of causing infections of the gastrointestinal tract in guinea pigs. Some of these bacteria are introduced through contaminated greens or vegetables or in contaminated water. One of the most common bacteria that causes intestinal disease in guinea pigs is Salmonella spp. Other bacterial species that may cause diarrhea and enteritis are Yersinia pseudotuberculosis, E. coli, Arizona spp., and Clostridium spp. In addition
to diarrhea, other common symptoms associated with intestinal disease are lethargy and weight loss. In other
cases, however, sudden death may occur before expression of these signs.

A veterinarian may elect to use aggressive antibiotic therapy and supportive care to treat this condition. A bacterial culture of the patient’s stool with antibiotic sensitivity will greatly assist the veterinarian in choosing an appropriate antibiotic to use.

Bacterial Pododermatitis (Food Pad Infection)
Severe infections of the footpads are very common among guinea pigs housed in cages with wire flooring. Fecal soiling of the wire potentiates the problem. The guinea pig’s front feet are most vulnerable to this condition.
Symptoms of this condition include swelling of the affected feet, lameness and reluctance to move. Improved sanitation and cage floor alterations are the initial steps in correcting the problem. In addition, a veterinarian should treat the feet themselves. Topical dressing with an antibiotic and periodic bandaging is often required. Depending on the severity of the damage, injectable antibiotics may also be necessary. Therapy may have to be carried out for a lengthy period of time to get full recovery. Unfortunately, a consequence of this condition is arthritis.

External Parasites (Lice and Mites)

Lice and mites are the most common external parasites of guinea pigs. Lice are tiny, wingless, flattened insects
that live within the hair coats of infested animals. Both adults and eggs are found attached to hair shafts of affected pets.

Mites are microscopic, spider-like organisms that infest the top layers of the skin in affected animals. Guinea pig
lice and mites are not known to parasitize man.

Mite infestations are usually more severe than lice. A specific mite, Trixacarus cavie, causes serious infestations in pet guinea pigs. This sarcoptic mite lives in the outer layers of skin causing an intense itching and scratching with considerable hair loss. In some cases, they present without the itch and scratching, but only hair loss and crusting of the skin. In other cases, the infestation and irritation is so severe that the pet causes significant self-inflicted wounds and exhibits wild running and circling behavior.

A veterinarian can diagnose this mite infestation by performing skin scrapings of affected areas and viewing them under the microscope. Successful treatment consists of one to four injections of a specific antiparasitic drug at approximately two week intervals. In the meantime, if wood shavings are used as bedding or litter, it should be replaced with paper toweling to make your pet more comfortable.

Transmission of Trixacarus cavie mites can occur only through direct contact between infested and non-infested guinea pigs. Therefore, pet guinea pigs are not likely to harbor this parasite unless they are recent additions or had previous exposure to mite-infested guinea pigs. For your pet’s sake, be sure that any guinea pig he/she comes in contact with is healthy and free of this and other parasites.

Lice infestations often go unnoticed. However, heavy infestations are usually accompanied with excessive itching, scratching and some hair loss. Scabbing on or around the ears may also be evident. Guineas pigs have two types
of biting lice that may parasitize them. Both irritate and abrade the skin’s surface and feed off the bodily fluids that exude through the superficial wounds they create.

A veterinarian can confirm the diagnosis of lice infestation by examination of the hair coat as well as microscopic examination of hairs from affected animals. Treatment is usually in the form of an insecticidal shampoo, which is prescribed by the veterinarian.

As with mites, lice transmission occurs through direct contact with infested guinea pigs. Therefore, pet guinea pigs are not likely to have this parasite unless they had previous exposure to lice-infested guinea pigs. For your pet’s sake, be sure that any guinea pig he/she comes in contact with is healthy and free of this and other parasites.

Guinea Pig Sensitivity to Certain Antibiotics
Guinea pigs are very sensitive to certain classes of antibiotics. For this reason, NEVER attempt treatment of your pet guinea pig at home without prior consultation with a veterinarian. Many antibiotics that are safe for other animals have been shown to be lethal to guinea pigs, whether given orally or by injection. In addition, even some topical antibiotics can produce serious detrimental results.

A partial list of potentially harmful antibiotics includes: ampicillin, penicillin, bacitracin, gentamicin, erythromycin, lincomycin, clindamycin, streptomycin, vancomycin and sometimes tetracyclines. Even if an antibiotic is not on this list, it does not ensure that it is safe to use. When improperly administered, any antibiotic can produce detrimental and often lethal results.

The primary mechanism behind this often lethal effect is a dramatic alteration of the normal microbial balance in the gastrointestinal tract. In addition to affecting the disease-causing bacteria in the body, they also interfere with the normal beneficial bacteria in the guinea pig’s digestive system. Guinea pigs have very delicate digestive systems, so any alteration can produce a cascade of events leading to serious illness or death. As well as causing disruption of the bacterial balance, these alterations also result in the production of harmful chemicals in the guinea pig’s body. Other antibiotics cause direct toxic effects to the guinea pig without initially disrupting the digestive system, often proving rapidly fatal.

Whenever a veterinarian prescribes any antibiotic, always supplement the guinea pig with about one-half teaspoon (2.5 cc) of plain yogurt twice daily. This therapy should continue for a couple days past the antibiotic therapy. Yogurt helps augment and replace the beneficial intestinal bacteria that are compromised by the antibiotic treatment.

The bottom line is never attempt treatment at home without first consulting with your veterinarian.

Special thanks to Drs. Harkness and Wagner, Drs. Rosskopf and Woerpel, Dr. Larry Peters and Dr. Lynn Anderson whose published information on this subject was compiled to produce this writing.

Guinea Pigs