Guinea Pigs
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Guinea Pigs: General Information (Part 1)
Scientific Classification-- Order: Rodentia, Cavia porcellus, also known as a cavy
Pet Types: English/Common (short-hair), Peruvian (long, straight, silky hair), Abyssinian (rough, wiry hair in
swirls). Hybrids of these types also occur.
Vaccine recommendations: None
Husbandry concerns: Guinea pigs should be kept indoors. They can suffer heat stroke when taken outside
without a proper shelter, even at 80ºF. Do not house with rabbits or have direct dog/cat contact due to
concerns with a type of bacterial pneumonia. Ideally, they should be housed in a container that allows side
ventilation. Bedding can include recycled newspaper, and newspaper. AVOID CEDAR and other wood
chips!! Cages need to be cleaned every other day to control ammonia odor/irritation from the urine and
maggot development. Some do well alone, others like a pal. A hide-box is often needed for those guinea
pigs that scare easily.
Nail trims/Tooth trims/Baths: Nail trims should be done periodically, often by the veterinarian if
uncooperative at home. Watch for the “quick” as in dogs or cats, though black nails can be difficult to see it
on. Tooth trims should never be done except by a trained veterinarian with the proper equipment! Serious
damage can be done. Most guinea pigs do not need teeth trims, especially the front incisors, except when
damaged by trauma or genetically malformed. Once malformed, they will always need periodic trims. The
back molars (check teeth) may be malocclused due to genetics or improper fiber in the diet. This can lead to
anorexia and drooling. The teeth are examined and trimmed under anesthesia. Baths can be given once a
month using a ferret, kitten or puppy shampoo. They do not like baths, so be ready. Towel dry and let them
go sulk. Ears can be cleaned gently and superficially with cotton balls. Excessive scratching may indicate
mites/lice, to be addressed by the veterinarian.
Diet: This is the area of greatest importance!!! Guinea pig preferences are hard to change and can cause
problems if they will not eat anything or the right things. Make changes slowly. The diet should consist
only of: 1) Free-choice alfalfa pellets until 8 months of age, then put on Timothy hay-based pellets.
2) Free-choice Timothy or mixed-grass hay. 3) Minimum of 1 cup per 4 pounds body weight of at
least three of the following vegetables: kale, alfalfa sprouts, basil, broccoli leaves, brussel sprouts,
carrot tops, cilantro, endive, parsley, outer cabbage leaves, raspberry leaves, wheat grass, radicchio,
dandelion greens, mustard/collard/beet greens, romaine lettuce, peppermint leaves, cabbage,
chicory and escarole. 4) ½ an orange, or red/green peppers, broccoli, tomatoes, kiwi, small
container of Tang) TWICE A WEEK.
Obesity is a problem with guinea pigs, so monitor weight at the veterinarian’s office. No treats. Yogurt is of
questionable use, because Lactobaccilus acidophilus is not even a normal bacteria in guinea pigs. Guinea
pigs do eat their own feces many times a day to provide B-Vitamins and extra protein. This is normal.
Water should be offered in a water bottle, but it is important to offer a water bowl until it is certain the
water bottle is being used. Guinea pigs love to play with the ball in the water bottle, so this may require
further cleaning of the cage. The bottle should be cleaned daily with a pipe cleaner, as these little guys like
to “backwash.” Water intake is very important for digestion. ALWAYS USE BOTTLED WATER!!!
Health care: Biannual exams; Urinalysis, fecal float, and an x-ray are recommended yearly. Dental
problems do occur in guinea pigs (see tooth trims). Neutering and spaying helps prevent reproductive
tumors, unexpected pregnancies, and can aid behavior modification. Common problems are diarrhea,
constipation, anorexia, tumors, pneumonia, mites/lice, scurvy, eye infections, and dental problems. Be very
careful not to use antibiotics on your own or to get some from a veterinarian inexperienced with guinea
pigs. The wrong types do more harm than good and can kill! Remember with any disease processes, the
sooner seen, the more successful we are at treating them!
Other information: They make wonderful pets since they are so docile, but they can move very fast and be
hard to catch if not hand-tamed. Body weight: 700-1200 grams (70-100 grams at birth); life span: 5-6
years; sexual maturity as early as 2 months of age; if they have not given birth to babies before reaching 6
months of age, then any subsequent litters may require a c-section, due to lack of stretching the pelvic
bones during maturing; gestation: 59-72 days; litter size: 1-13 (usually 2-4); hand-raising baby guinea pigs
can be done, but call us for the specifics; males have scrotal pouches with large testes, while the female
genital region forms a “Y”; both sexes have mammary glands.
Scientific Classification-- Order: Rodentia, Cavia porcellus, also known as a cavy
Pet Types: English/Common (short-hair), Peruvian (long, straight, silky hair), Abyssinian (rough, wiry hair in
swirls). Hybrids of these types also occur.
Vaccine recommendations: None
Husbandry concerns: Guinea pigs should be kept indoors. They can suffer heat stroke when taken outside
without a proper shelter, even at 80ºF. Do not house with rabbits or have direct dog/cat contact due to
concerns with a type of bacterial pneumonia. Ideally, they should be housed in a container that allows side
ventilation. Bedding can include recycled newspaper, and newspaper. AVOID CEDAR and other wood
chips!! Cages need to be cleaned every other day to control ammonia odor/irritation from the urine and
maggot development. Some do well alone, others like a pal. A hide-box is often needed for those guinea
pigs that scare easily.
Nail trims/Tooth trims/Baths: Nail trims should be done periodically, often by the veterinarian if
uncooperative at home. Watch for the “quick” as in dogs or cats, though black nails can be difficult to see it
on. Tooth trims should never be done except by a trained veterinarian with the proper equipment! Serious
damage can be done. Most guinea pigs do not need teeth trims, especially the front incisors, except when
damaged by trauma or genetically malformed. Once malformed, they will always need periodic trims. The
back molars (check teeth) may be malocclused due to genetics or improper fiber in the diet. This can lead to
anorexia and drooling. The teeth are examined and trimmed under anesthesia. Baths can be given once a
month using a ferret, kitten or puppy shampoo. They do not like baths, so be ready. Towel dry and let them
go sulk. Ears can be cleaned gently and superficially with cotton balls. Excessive scratching may indicate
mites/lice, to be addressed by the veterinarian.
Diet: This is the area of greatest importance!!! Guinea pig preferences are hard to change and can cause
problems if they will not eat anything or the right things. Make changes slowly. The diet should consist
only of: 1) Free-choice alfalfa pellets until 8 months of age, then put on Timothy hay-based pellets.
2) Free-choice Timothy or mixed-grass hay. 3) Minimum of 1 cup per 4 pounds body weight of at
least three of the following vegetables: kale, alfalfa sprouts, basil, broccoli leaves, brussel sprouts,
carrot tops, cilantro, endive, parsley, outer cabbage leaves, raspberry leaves, wheat grass, radicchio,
dandelion greens, mustard/collard/beet greens, romaine lettuce, peppermint leaves, cabbage,
chicory and escarole. 4) ½ an orange, or red/green peppers, broccoli, tomatoes, kiwi, small
container of Tang) TWICE A WEEK.
Obesity is a problem with guinea pigs, so monitor weight at the veterinarian’s office. No treats. Yogurt is of
questionable use, because Lactobaccilus acidophilus is not even a normal bacteria in guinea pigs. Guinea
pigs do eat their own feces many times a day to provide B-Vitamins and extra protein. This is normal.
Water should be offered in a water bottle, but it is important to offer a water bowl until it is certain the
water bottle is being used. Guinea pigs love to play with the ball in the water bottle, so this may require
further cleaning of the cage. The bottle should be cleaned daily with a pipe cleaner, as these little guys like
to “backwash.” Water intake is very important for digestion. ALWAYS USE BOTTLED WATER!!!
Health care: Biannual exams; Urinalysis, fecal float, and an x-ray are recommended yearly. Dental
problems do occur in guinea pigs (see tooth trims). Neutering and spaying helps prevent reproductive
tumors, unexpected pregnancies, and can aid behavior modification. Common problems are diarrhea,
constipation, anorexia, tumors, pneumonia, mites/lice, scurvy, eye infections, and dental problems. Be very
careful not to use antibiotics on your own or to get some from a veterinarian inexperienced with guinea
pigs. The wrong types do more harm than good and can kill! Remember with any disease processes, the
sooner seen, the more successful we are at treating them!
Other information: They make wonderful pets since they are so docile, but they can move very fast and be
hard to catch if not hand-tamed. Body weight: 700-1200 grams (70-100 grams at birth); life span: 5-6
years; sexual maturity as early as 2 months of age; if they have not given birth to babies before reaching 6
months of age, then any subsequent litters may require a c-section, due to lack of stretching the pelvic
bones during maturing; gestation: 59-72 days; litter size: 1-13 (usually 2-4); hand-raising baby guinea pigs
can be done, but call us for the specifics; males have scrotal pouches with large testes, while the female
genital region forms a “Y”; both sexes have mammary glands.
Guinea Pigs: Care and Keeping (Part 2)
Guinea pigs are rodents (related to chinchillas and porcupines) that originated in the Andes Mountains
region of South America. They were probably first domesticated by the Indians of Peru, who used them for
food and as sacrificial offerings for their gods. In the 16th century, Dutch explorers introduced guinea pigs
to Europe, and selective breeding and captive rearing began in earnest.
Guinea pigs are very popular pets because of their availability, docile temperaments, tendency not to
bite or scratch when handled, and relatively clean habits. They are not long-lived, which can be
disconcerting to owners (especially children). Many parents, however, believe that having their children
experience the relatively short period of companionship and subsequent death is a meaningful way to
expose children to the “ups and downs” of life.
In their natural habitat, guinea pigs live in open, grassy areas. They seek shelter in naturally protected
areas or burrows deserted by other animals. Guinea pigs are sociable animals and tend to live in groups.
They are strictly herbivorous (plant-eating) and do most of their foraging for grasses, roots, fruits and seeds
in the late afternoon and early evening.
For many years guinea pigs have been used in biomedical research laboratories. Consequently, their
medical problems have been traditionally approached on a group basis, rather than on an individual basis.
As a result, very little practical information exists on the medical care and treatment of individual pet guinea
pigs. Even less information is available to owners on the responsible home care of guinea pigs and
recognition of their medical problems.
Handling and Restraint
Guinea pigs rarely violently struggle when they are being picked up but often make a “squeal of
protest,” which sounds pig-like to many people. Nevertheless, great care should be taken not to injure
them when picking them up. A guinea pig should be approached with two hands. One is placed under the
guinea pig’s chest and abdomen, and the other supports its hindquarters. Adults and those that are
pregnant should receive gentle, bur firm, and total support.
One of the most desirable features of guinea pigs as pets is that they rarely bite when being handled or
restrained. One reference indicates that only 1 in 400 will bite under these circumstances.
Housing
Proper housing is a major factor in the maintenance of healthy guinea pigs. The well-being of the
animals must be a primary consideration. Guinea pigs can be housed within enclosures made of wire,
stainless steel, durable plastic or glass. The last 3 materials are preferred because they resist corrosion.
Wood and similar materials should not be used in construction of enclosures because they are difficult to
clean and cannot withstand gnawing. The construction and design of the enclosure must be free of sharp
edges and other potential hazards.
The enclosure must be roomy enough to allow normal activities and breeding, if the latter is desired.
One reference recommends at least 100 square inches of floor area per adult, whereas breeders should be
allowed 180 square inches per animal.
The enclosure can be open at the top, provided that its sides are at least 7-8 inches high. Male guinea
pigs (especially breeding males) require enclosures at least 10 inches high. Males tend to be more
rambunctious.
Guinea pigs can be housed on wire mesh (suitable for housing rats) but it is not recommended. Though
wire mesh allows urine and most fecal pellets to drop through, thereby keeping the bedding and the
residents cleaner, guinea pigs housed for long periods on wire tend to develop serious injuries to the
bottoms of their feet (see section on foot pad infections). Further, a leg may be broken if it becomes
entangled in the mesh. This is most often a problem with guinea pigs that have not been reared on wire
mesh, and occurs soon after they have been introduced onto it.
Enclosures that provide solid flooring and an adequate supply of a preferred bedding are best for pet
guinea pigs. They should be easy to clean, well lighted and adequately ventilated (see Vital Statistics for
preferred temperature and relative humidity ranges). Bedding must be clean, nontoxic, absorbent, relatively
dust-free and easy to replace. Shredded paper or wood shavings are preferred bedding materials.
Sawdust should be avoided because it tends to collect within the external genitalia of males, forming an
impaction. Rarely does this impaction interfere with urination, but it may inhibit successful breeding.
Guinea pigs seem most comfortable when they are spared exposure to excessive noise, needless
excitement and confusion, and other stresses. Sudden environmental changes should also be prevented.
Guinea pigs have two types of reactions when startled by a loud noise or sudden movement or when
placed in a strange environment. They may “freeze” completely motionless (for up to 20 minutes), or they
may panic. Panic involves erratic running and leaping, often accompanied by shrill squealing. Groups of
guinea pigs may stampede in a circle, often trampling the younger residents within the enclosure. A panic
reaction scatters bedding and food, fouling the food and water containers. Visual security (a place into
which they can retreat when frightened) should always be provided. Rectangular enclosures containing
barriers also reduce the tendency to stampede and circle.
Hygiene
The frequency with which the enclosure is cleaned depends on its design, the materials out of which it is
made, and the number of guinea pigs that reside within it. As a general rule of thumb, the enclosure and all
cage “furniture” should be cleaned and disinfected once weekly. Food and water containers should be
cleaned and disinfected once daily. More than one set of containers should be maintained, and the soiled
set should be washed in a dishwasher, if possible. Vigorous scrubbing of the enclosure and “furniture” with
hot water and soap and a thorough rinse should be followed by use of a disinfectant (Roccal-D: Winthrop).
Vinegar is often required to remove the scale deposited by the crystalline urine of guinea pigs.
Food and Water
Good-quality food and fresh, clean water must be readily available at all times. Commercially available
pelleted chows provide all of the essential nutrients, as long as the pellets are fresh and wholesome when
offered. Some guinea pig owners are tempted to feed rabbit pellets, assuming that they are roughly
equivalent to guinea pig pellets, but this is not so. Unlike most mammals (including rabbits), guinea pigs
require a high level of the vitamin, folic acid. Unlike rabbits, guinea pigs cannot manufacture their own
Vitamin C and must, therefore, receive it from an outside source. Interestingly, people and our primate
relatives share this dependence on Vitamin C from the food we consume. Pellets milled for guinea pigs take
these special requirements into consideration and are appropriately fortified with these two nutrients,
among many other essential ones.
Guinea pig chows generally contain 18-20% protein, 16% fiber and about 1 gram of Vitamin C per
kilogram of ration. Even when the fresh pellets are properly stored in a cool, dry place, about half of the
Vitamin C content is degraded and lost within 6 weeks of manufacture. Therefore, the diet should be
supplemented with Vitamin C as follows: 200 mg of ascorbic acid (Vitamin C) should be added to about 1
quart of drinking water, made up fresh every 12 hours, or a single guinea pig should be offered one handful
of kale or cabbage or ¼ of an orange daily.
Researchers are not in agreement on the advisability of adding other items to the balanced ration
(pelleted chows). We recommend that fresh greens, hay and small amounts of fruit be offered daily with
several precautions: These items should not exceed 10-15% of the daily diet. Further, the fresh items must
be thoroughly washed to avoid pesticide residues and possible bacterial contamination.
All foods should be provided in heavy ceramic crocks that resist tipping over. The sides of the crocks
should be high enough to keep bedding and fecal pellets out of the food, or the crocks should be elevated
slightly above the bedding.
Water is most easily made available and kept free from contamination by providing it in one or more
water bottles equipped with “sipper” tubes. Guinea pigs tend to contaminate and clog their water bottles
more than other pet rodents by chewing on the end of the sipper tube and “backwashing” food particles
into it. For this reason, all food and water containers should be cleaned and disinfected daily.
Guinea pigs tend to be creatures of habit and do not tolerate changes in the presentation, taste, odor,
texture or form of their food and water. Pet owners should avoid making radical changes in the food and
water containers. Any changes in the food itself should be made gradually. Failure to do so usually results
in the guinea pigs’ refusing food and water, which can lead to disease.
Breeding Considerations
The single most important breeding consideration is that female guinea pigs should be first bred before
7 months of age. If the first breeding is delayed beyond this time, serious (sometimes life-threatening)
problems with delivery are encountered. Females should be first bred between 3 and 7 months of age.
Males should be 3-4 months old at their first breeding.
The guinea pig’s heat cycle lasts 16 days. The period during which the female is receptive to the male
and will allow breeding lasts about 8 hours. Female guinea pigs can come back into heat 6-15 hours after
giving birth. This is called “postpartum estrus,” which means that they can be nursing a litter and pregnant
at the same time!
Pregnancy lasts an average of 63068 days. The larger the litter, the shorter the term of pregnancy and
vice versa. The duration of pregnancy for guinea pigs is unusually long when compared to that of other
rodents.
Pregnant sows (females) exhibit a grossly enlarged abdomen during the latter stages of pregnancy. It
is not uncommon for their body weight to double during pregnancy. The time of delivery may be difficult to
determine because of the relatively long gestation period and because pregnant sows do not build nests.
However, the week before a sow is about to deliver a litter, a slowly widening separation of the pelvis
develops just in front of the external genitalia. This separation reaches slightly more than one inch in the
hours just before delivery.
This separation of the pelvis does not develop in females that are bred for the first time after 7 months
of age, creating an impossible and tragic situation. Delivery of the young is not possible and a cesarean
section must usually be performed to save the life of the sow and her babies.
An uncomplicated delivery usually requires about ½ hour, with an average of 5 minutes between
delivery of each baby. Litter sizes range from 1 to 6 young, with an average of 3-4. Litters resulting from
the first breeding are usually very small. Abortions and stillbirths are common with guinea pigs throughout
their breeding lives.
The young are born relatively mature. They are unusually large and fully furred, and can walk about.
They also have teeth and open eyes at this time. Even though newborn guinea pigs can eat solid food and
drink water from a container, they should be allowed to nurse their mother for at least 2 weeks.
CONDITIONS REQUIRING VETERINARY ATTENTION
Malocclusion of Premolar Teeth (Slobbers)
A common problem of guinea pigs (especially those over 2-3 years old) results when the upper and
lower premolar teeth (the most forward cheek teeth) meet improperly while chewing. In time, this problem
results in abnormal wear of these teeth. This in turn causes entrapment of and continual injury to the
tongue. Affected animals try to eat but cannot chew and swallow food. Drooling results in a continually
moist mouth and chin. Weight loss is often dramatic.
A veterinarian must be consulted as soon as possible if this condition is suspected. The diagnosis is
confirmed upon direct visual examination of the mouth. Correction of the problem involves general
anesthesia and aggressive trimming or filing of the overgrown teeth. This is a difficult procedure because of
the guinea pig’s extremely small mouth opening. Force feedings and antibiotics are usually necessary for a
number of days before and after this procedure has been performed.
There is no permanent solution or correction for this problem. Periodic trimming or filing is almost
always necessary. Guinea pigs with this problem should never be bred so as to prevent passing this most
undesirable trait to their offspring.
Vitamin C Deficiency
(Scurvy or Scorbutus)
Guinea pigs cannot manufacture Vitamin C and must receive an adequate supply of it from outside food
sources. Vitamin C deficiency results in scurvy, which is characterized by inappetence, swollen, painful joints
and ribs, reluctance to move, poor bone and teeth development, and spontaneous bleeding from the gums
and into muscle.
Adequate levels of Vitamin C are always included in the formulation of pelleted diets for guinea pigs.
Often, however, handling and improper storage (exposure to light, heat and dampness) f the feed pellets
results in loss of Vitamin C. Therefore, even guinea pigs fed presumably reliable pelleted diets may develop
scurvy if the diet’s Vitamin C content has been reduced or lost.
A veterinarian should be consulted if this disease is suspected so that the diagnosis can be confirmed.
The veterinarian will prescribe a program of Vitamin C supplementation (via food or water or injection) to
reverse the signs.
Difficulties During Birth
Dystocia: Female guinea pigs intended for breeding must be first bred before 7 months of age. If the
first breeding is delayed beyond this time, serious (sometimes life-threatening) problems with delivery are
encountered.
A portion of the pregnant sow’s pelvis must widen for successful delivery of her young. This separation
fails to develop in females bred for the first time after 7 months of age, usually necessitating a cesarean
section to deliver the young and save the sow’s life.
Signs of dystocia include straining and uterine bleeding. Veterinary help must be sought immediately.
The veterinarian will evaluate the pregnant sow by direct exam and by taking x-rays. If a vaginal delivery of
the young is not possible, a cesarean section will be necessary.
Pregnancy toxemia is a serious condition that usually occurs in overweight sows in their first or second
pregnancy. Signs are most likely to be noted over 105 days during the last 2 weeks of pregnancy or the
first week following birth. These include inappetence, depression, weakness, reluctance to move,
incoordination, difficulty breathing, coma and death. Some afflicted sows may show no signs and suddenly
die.
There is no single cause for this condition, but stress and obesity are major predisposing factors.
Others include advancing age, lack of exercise, fasting just before onset of signs, and a large number of
developing fetuses. The fundamental underlying problem seems to be inadequate blood flow to the uterus.
Sows showing any of these signs must be seen immediately by a veterinarian. Because treatment is
often unsuccessful, prevention of pregnancy toxemia is of paramount importance. Pregnant sows should
not be allowed to become obese. Fasting and stress must be avoided, especially in the last several weeks
of pregnancy. Pregnant sows must be supplied with fresh water at all times and fed a nutritious diet.
Hair Loss
Hair loss or thinning of the hair is a common problem of female guinea pigs that have been repeatedly
bred. Those sows tend to lose hair with each successive pregnancy.
Hair loss is frequently noted among juvenile guinea pigs in a weakened state at or around the time of
weaning. “Barbering” also results in hair loss. This vice (bad habit) occurs when guinea pigs habitually
chew on the haircoats of guinea pigs that are lower in the social “pecking order.” Younger guinea pigs, in
particular, can lose substantial amounts of hair as a result of this activity.
Hair can also be lost because of fungal disease and external parasite infestations.
Heat Stress (Heat Stroke)
Guinea pigs are especially 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, crowding and stress are additional predisposing factors.
Signs of heat stroke include panting, slobbering, weakness, refusal to move about, delirium, convulsions
and eventually death. Heat stroke is treatable if recognized relatively early. Heat-stressed guinea pigs
should be immediately sprayed with or bathed in cool water. Once this first-aid is undertaken, a
veterinarian should be contacted immediately.
Prevention of heat stroke involves providing adequate shade from the sun (if guinea pigs are housed
outdoors) and adequate ventilation (if housed indoors). A continuous light mist or spray of water and/or a
fan operating over a container of ice can be directed at a guinea pig within its enclosure to lower the air
temperature, whether the guinea pig is housed indoors or outdoors.
Cancer
Cancer is a relatively rare problem of guinea pigs. As with most animals, it is most likely to affect older
guinea pigs. Most tumors are benign and involve the skin and respiratory tract lining. Cancer may also
affect the reproductive tract, mammary glands (breasts) and blood (leukemia).
Footpad Infections (Bacterial Pododermatitis)
Serious (sometimes crippling) infections of the footpads are common among pet guinea pigs housed
continuously on wire. The other major predisposing factor is fecal soiling of wire-bottomed enclosures. The
front feet of overweight animals are especially vulnerable to this condition.
Signs include swelling of the feet, lameness, reluctance to move, and inappetence. The flooring of the
enclosure must be changed and overall sanitation must be improved. A veterinarian must be consulted
regarding treatment of affected feet. Topical dressing with an antibiotic and periodic bandaging are
necessary during the usually lengthy recovery period. Injectable antibiotics are often used by veterinarians
in treatment of this condition. Arthritis is a frequent and unfortunate consequence of these infections.
Cervical “Lumps” (Cervical Lymphadenitis)
Abscessation of the lymph nodes immediately beneath the lower jaw, in the upper neck, usually results
when coarse foods (such as hay) injure the lining of the mouth or when superficial wounds penetrate the
skin over these lymph nodes. Bacterial invasion causes painful, swollen abscesses under the lower jaw.
Sometimes these abscesses break open and exude a thick, creamy yellow-white pus.
A veterinarian can perform a bacterial culture of the pus with antibiotic sensitivity testing to determine
the appropriate antibiotic to use by injection. If the abscesses are large, surgical removal and aggressive
antibiotic therapy may be recommended.
Pneumonia
Pneumonia is one of the most common bacterial diseases of pet guinea pigs. A number of potential
disease-causing bacteria may inhabit the respiratory tracts of otherwise normal guinea pigs. Stress,
inadequate diet, and improper home care often predispose a pet guinea pig to respiratory infection. Signs
of pneumonia may include labored or rapid breathing, discharge from eyes and nostrils, lethargy and
inappetence. Some animals show no signs at all before dying suddenly.
Middle and inner ear infections occasionally result from respiratory disease in guinea pigs. Additional
signs may include incoordination, tilting of the head, circling to one side, and rolling.
A veterinarian must be consulted about this serious bacterial infection. Aggressive antibiotic therapy by
injection and appropriate supportive care are necessary. Bacterial culture and antibiotic sensitivity testing
help the veterinarian select an appropriate antibiotic. Unfortunately, even though the signs of infection can
be relieved, the causative bacteria cannot be eliminated.
Rabbits and rats harbor at least one of the bacteria known to cause pneumonia in guinea pigs.
Therefore, it is wise not to house these animals with or near guinea pigs.
Intestinal Infections (Bacterial Enteritis)
Numerous bacteria can cause infections of the gastrointestinal tract of guinea pigs. Some of these
bacteria are introduced on contaminated greens and vegetables or in contaminated water.
Intestinal infections can manifest themselves as sudden death without prior signs, or as a more lengthy
period of illness characterized by lethargy and marked weight loss. Diarrhea may or may not be noted in
either case.
A veterinarian will recommend aggressive antibiotic therapy and appropriate supportive care. A
bacterial culture of the patient’s stool and antibiotic sensitivity testing help the veterinarian select the
appropriate antibiotic.
Ringworm
Ringworm is a skin disease caused by a fungus similar to the one that causes athlete’s foot in people.
Young guinea pigs are usually more susceptible than adults. Ringworm in guinea pigs is generally
characterized by patchy hair loss on the face, nose and ears. The skin in these areas may appear flaky.
Areas of hair loss may extend along the top side of the trunk.
A veterinarian must confirm the diagnosis and prescribe topical and/or oral medication. The medications
to be used depend on the number of ringworm areas present and their distribution on the body.
Ringworm can be transmitted from guinea pigs to people. It is, therefore, important to limit or restrict
handling of infected guinea pigs (especially by young children) until their disease has been successfully
treated. If handling is necessary, the handler should thoroughly wash his hands afterward.
Viral Diseases
Most viral infections of pet guinea pigs are either mild or unapparent.
Lice Infestation
Lice and mites are the most common external parasites of guinea pigs. Lice are tiny, wingless, flattened
insects that live within the haircoat. Both the adults and their eggs are found attached to individual hairs.
Guinea pigs may be parasitized by two types of biting lice. Both abrade the skin surface and feed off of
the body fluids that exude through the very superficial wounds they create.
Light infestations usually go unnoticed. Heavy infestations are usually accompanied with excessive
itching, scratching and some hair loss. Scabs may also be evident around the ears.
A veterinarian can confirm the diagnosis by direct examination of the haircoat. Direct examination is
usually all that is necessary, though use of a microscope is very helpful. The veterinarian will usually
prescribe an insecticidal shampoo to treat affected guinea pigs.
Lice can be transmitted by direct and intimate contact between infested and uninfested guinea pigs.
Therefore, pet guinea pigs are very unlikely to harbor these parasites unless they are recent acquisitions
that were previously in contact with louse-infested guinea pigs. Established pet guinea pigs could also be
infested by being placed in close contact with new, infested guinea pigs. Guinea pig lice do not parasitize
people.
Mite Infestations (Mange)
A mite similar to the scabies mite of people causes serious infestations in pet guinea pigs. Mites are
microscopic, spider-like organisms that live within the outer layers of the skin. They usually cause intense
scratching and significant hair loss. Some cases without scratching have been reported. Some guinea pigs
are so miserable because of the infestation that their constant scratching produces serious wounds. They
may run wildly or in circles, and occasionally even have convulsions.
A veterinarian must do a number of scrapings of the skin to confirm the diagnosis. Successful treatment
consists of 1-4 injections of a specific drug (ivermectin) 10-14 days apart. Any wood shavings within the
enclosure should be replaced by white paper toweling during treatment to help make the patient more
comfortable.
Mites can only be transmitted by direct contact between infested and uninfested guinea pigs.
Established pet guinea pigs could also be infested by being placed in close contact with new, infested
guinea pigs. Guinea pig mites do not parasitize people.
Intestinal Parasite Problems
Intestinal parasites are usually not a significant problem in pet guinea pigs. A protozoan (one-celled
organism) parasite may cause coccidiosis in guinea pigs. Signs of this disease include weakness, diarrhea
and severe weight loss. Pinworm infections of guinea pigs usually go unnoticed.
Both of these parasitisms can be diagnosed by a veterinarian by stool examinations. Both are treatable
using specific drugs prescribed by the veterinarian. Neither parasite problem is transmissible to people.
SENSITIVITY OF GUINEA PIGS TO CERTAIN ANTIBIOTICS
Guinea pigs as a group are unusually sensitive to certain antibiotics, whether they are given orally or by
injection. Potentially harmful antibiotics include ampicillin, penicillin, bacitracin, erythromycin, lincomycin,
gentamicin, clindamycin, streptomycin, vancomycin and sometimes tetracycline. Interestingly, even certain
antibiotics used topically may produce lethal effects.
The major way in which certain antibiotics cause reactions is by altering the normal microbial balance
within the gastrointestinal tract. Once the normal intestinal microfloral balance has been upset, certain
bacterial multiply to abnormally large numbers. The multiplying bacteria produce harmful chemicals that can
have lethal effects.
Certain antibiotics (streptomycin, dihydrostreptomycin) are directly toxic and do not alter the microbial
balance within the gastrointestinal tract. These antibiotics should never be used in guinea pigs.
Though injectable antibiotics can cause the problems described above, oral antibiotics should never be
given to guinea pigs unless they are prescribed by a veterinarian. If oral or injectable antibiotics are
prescribed, 2 ½ cc (1/2 teaspoon) of plain, white yogurt should be given orally to the treated animal morning
and evening for the duration of the antibiotic therapy and for an additional 5-7 days afterward. Yogurt helps
replace those beneficial intestinal bacteria that often perish during antibiotic treatment.
HUMAN ALLERGIES TO GUINEA PIG DANDER
Certain people are allergic to the hair and/or dander of guinea pigs. People working with guinea pigs in
laboratory situations are more likely to develop such allergies because of their continual association with
them. Signs include itchy eyes, sneezing, runny nose, persistent cough, shortness of breath, wheezing,
rash, and anaphylactic shock (a true medical emergency).
Owners of pet guinea pigs may also be susceptible, and a medical doctor should be consulted about
suspected allergy problems if a guinea pig is kept as a pet in the household. Guinea pig owners with such a
suspected allergy may want to sonsult an allergist.
VITAL STATISTICS
Scientific name:
Cavia porcellus
Life span:
3-4 years
Potential life span:
6-7 years
Desirable environmental temperature range:
65-75 F
Desirable relative humidity range:
40-70% (50% is considered ideal)
Recommended age at first breeding:
Males: 3-4 months
Females: 3-7 months
(not after 7 months)
Length of estrous (heat) cycle:
16 days
Length of estrus (period when female is receptive to male):
8 hours
Gestation (pregnancy) period:
Averages 63-68 days
Average litter size:
3-4 young (range, 1-6)
Age at weaning:
2-3 weeks
CLUBS AND ORGANIZATIONS
A wealth of additional useful information may be obtained by joining one or more of the organizations listed
below. All of these groups publish newsletters or bulletins.
American Cavy Breeders Association
(www.acbaonline.com)
c/o Lenore Gergen
16540 Hogan Avenue
Hastings, MN 55033
651-283-0202
McCavy@aol.com
California State Rabbit & Cavy Breeders Association
(www.csrcba.org)
Nancy Hinkston
1311 Poe Lane
San Jose, CA 95130
Jack Pine Guinea Pig Rescue
(www.jpgpr.com)
26515 Apollo Street NE
Stacy, Minnesota 55079
SUGGESTED READING
Harkness and Wagner: The Biology and Medicine of Rabbits and Rodents. 3rd ed. Lea & Febiger,
Philadelphia, 1988.
Guinea pigs are rodents (related to chinchillas and porcupines) that originated in the Andes Mountains
region of South America. They were probably first domesticated by the Indians of Peru, who used them for
food and as sacrificial offerings for their gods. In the 16th century, Dutch explorers introduced guinea pigs
to Europe, and selective breeding and captive rearing began in earnest.
Guinea pigs are very popular pets because of their availability, docile temperaments, tendency not to
bite or scratch when handled, and relatively clean habits. They are not long-lived, which can be
disconcerting to owners (especially children). Many parents, however, believe that having their children
experience the relatively short period of companionship and subsequent death is a meaningful way to
expose children to the “ups and downs” of life.
In their natural habitat, guinea pigs live in open, grassy areas. They seek shelter in naturally protected
areas or burrows deserted by other animals. Guinea pigs are sociable animals and tend to live in groups.
They are strictly herbivorous (plant-eating) and do most of their foraging for grasses, roots, fruits and seeds
in the late afternoon and early evening.
For many years guinea pigs have been used in biomedical research laboratories. Consequently, their
medical problems have been traditionally approached on a group basis, rather than on an individual basis.
As a result, very little practical information exists on the medical care and treatment of individual pet guinea
pigs. Even less information is available to owners on the responsible home care of guinea pigs and
recognition of their medical problems.
Handling and Restraint
Guinea pigs rarely violently struggle when they are being picked up but often make a “squeal of
protest,” which sounds pig-like to many people. Nevertheless, great care should be taken not to injure
them when picking them up. A guinea pig should be approached with two hands. One is placed under the
guinea pig’s chest and abdomen, and the other supports its hindquarters. Adults and those that are
pregnant should receive gentle, bur firm, and total support.
One of the most desirable features of guinea pigs as pets is that they rarely bite when being handled or
restrained. One reference indicates that only 1 in 400 will bite under these circumstances.
Housing
Proper housing is a major factor in the maintenance of healthy guinea pigs. The well-being of the
animals must be a primary consideration. Guinea pigs can be housed within enclosures made of wire,
stainless steel, durable plastic or glass. The last 3 materials are preferred because they resist corrosion.
Wood and similar materials should not be used in construction of enclosures because they are difficult to
clean and cannot withstand gnawing. The construction and design of the enclosure must be free of sharp
edges and other potential hazards.
The enclosure must be roomy enough to allow normal activities and breeding, if the latter is desired.
One reference recommends at least 100 square inches of floor area per adult, whereas breeders should be
allowed 180 square inches per animal.
The enclosure can be open at the top, provided that its sides are at least 7-8 inches high. Male guinea
pigs (especially breeding males) require enclosures at least 10 inches high. Males tend to be more
rambunctious.
Guinea pigs can be housed on wire mesh (suitable for housing rats) but it is not recommended. Though
wire mesh allows urine and most fecal pellets to drop through, thereby keeping the bedding and the
residents cleaner, guinea pigs housed for long periods on wire tend to develop serious injuries to the
bottoms of their feet (see section on foot pad infections). Further, a leg may be broken if it becomes
entangled in the mesh. This is most often a problem with guinea pigs that have not been reared on wire
mesh, and occurs soon after they have been introduced onto it.
Enclosures that provide solid flooring and an adequate supply of a preferred bedding are best for pet
guinea pigs. They should be easy to clean, well lighted and adequately ventilated (see Vital Statistics for
preferred temperature and relative humidity ranges). Bedding must be clean, nontoxic, absorbent, relatively
dust-free and easy to replace. Shredded paper or wood shavings are preferred bedding materials.
Sawdust should be avoided because it tends to collect within the external genitalia of males, forming an
impaction. Rarely does this impaction interfere with urination, but it may inhibit successful breeding.
Guinea pigs seem most comfortable when they are spared exposure to excessive noise, needless
excitement and confusion, and other stresses. Sudden environmental changes should also be prevented.
Guinea pigs have two types of reactions when startled by a loud noise or sudden movement or when
placed in a strange environment. They may “freeze” completely motionless (for up to 20 minutes), or they
may panic. Panic involves erratic running and leaping, often accompanied by shrill squealing. Groups of
guinea pigs may stampede in a circle, often trampling the younger residents within the enclosure. A panic
reaction scatters bedding and food, fouling the food and water containers. Visual security (a place into
which they can retreat when frightened) should always be provided. Rectangular enclosures containing
barriers also reduce the tendency to stampede and circle.
Hygiene
The frequency with which the enclosure is cleaned depends on its design, the materials out of which it is
made, and the number of guinea pigs that reside within it. As a general rule of thumb, the enclosure and all
cage “furniture” should be cleaned and disinfected once weekly. Food and water containers should be
cleaned and disinfected once daily. More than one set of containers should be maintained, and the soiled
set should be washed in a dishwasher, if possible. Vigorous scrubbing of the enclosure and “furniture” with
hot water and soap and a thorough rinse should be followed by use of a disinfectant (Roccal-D: Winthrop).
Vinegar is often required to remove the scale deposited by the crystalline urine of guinea pigs.
Food and Water
Good-quality food and fresh, clean water must be readily available at all times. Commercially available
pelleted chows provide all of the essential nutrients, as long as the pellets are fresh and wholesome when
offered. Some guinea pig owners are tempted to feed rabbit pellets, assuming that they are roughly
equivalent to guinea pig pellets, but this is not so. Unlike most mammals (including rabbits), guinea pigs
require a high level of the vitamin, folic acid. Unlike rabbits, guinea pigs cannot manufacture their own
Vitamin C and must, therefore, receive it from an outside source. Interestingly, people and our primate
relatives share this dependence on Vitamin C from the food we consume. Pellets milled for guinea pigs take
these special requirements into consideration and are appropriately fortified with these two nutrients,
among many other essential ones.
Guinea pig chows generally contain 18-20% protein, 16% fiber and about 1 gram of Vitamin C per
kilogram of ration. Even when the fresh pellets are properly stored in a cool, dry place, about half of the
Vitamin C content is degraded and lost within 6 weeks of manufacture. Therefore, the diet should be
supplemented with Vitamin C as follows: 200 mg of ascorbic acid (Vitamin C) should be added to about 1
quart of drinking water, made up fresh every 12 hours, or a single guinea pig should be offered one handful
of kale or cabbage or ¼ of an orange daily.
Researchers are not in agreement on the advisability of adding other items to the balanced ration
(pelleted chows). We recommend that fresh greens, hay and small amounts of fruit be offered daily with
several precautions: These items should not exceed 10-15% of the daily diet. Further, the fresh items must
be thoroughly washed to avoid pesticide residues and possible bacterial contamination.
All foods should be provided in heavy ceramic crocks that resist tipping over. The sides of the crocks
should be high enough to keep bedding and fecal pellets out of the food, or the crocks should be elevated
slightly above the bedding.
Water is most easily made available and kept free from contamination by providing it in one or more
water bottles equipped with “sipper” tubes. Guinea pigs tend to contaminate and clog their water bottles
more than other pet rodents by chewing on the end of the sipper tube and “backwashing” food particles
into it. For this reason, all food and water containers should be cleaned and disinfected daily.
Guinea pigs tend to be creatures of habit and do not tolerate changes in the presentation, taste, odor,
texture or form of their food and water. Pet owners should avoid making radical changes in the food and
water containers. Any changes in the food itself should be made gradually. Failure to do so usually results
in the guinea pigs’ refusing food and water, which can lead to disease.
Breeding Considerations
The single most important breeding consideration is that female guinea pigs should be first bred before
7 months of age. If the first breeding is delayed beyond this time, serious (sometimes life-threatening)
problems with delivery are encountered. Females should be first bred between 3 and 7 months of age.
Males should be 3-4 months old at their first breeding.
The guinea pig’s heat cycle lasts 16 days. The period during which the female is receptive to the male
and will allow breeding lasts about 8 hours. Female guinea pigs can come back into heat 6-15 hours after
giving birth. This is called “postpartum estrus,” which means that they can be nursing a litter and pregnant
at the same time!
Pregnancy lasts an average of 63068 days. The larger the litter, the shorter the term of pregnancy and
vice versa. The duration of pregnancy for guinea pigs is unusually long when compared to that of other
rodents.
Pregnant sows (females) exhibit a grossly enlarged abdomen during the latter stages of pregnancy. It
is not uncommon for their body weight to double during pregnancy. The time of delivery may be difficult to
determine because of the relatively long gestation period and because pregnant sows do not build nests.
However, the week before a sow is about to deliver a litter, a slowly widening separation of the pelvis
develops just in front of the external genitalia. This separation reaches slightly more than one inch in the
hours just before delivery.
This separation of the pelvis does not develop in females that are bred for the first time after 7 months
of age, creating an impossible and tragic situation. Delivery of the young is not possible and a cesarean
section must usually be performed to save the life of the sow and her babies.
An uncomplicated delivery usually requires about ½ hour, with an average of 5 minutes between
delivery of each baby. Litter sizes range from 1 to 6 young, with an average of 3-4. Litters resulting from
the first breeding are usually very small. Abortions and stillbirths are common with guinea pigs throughout
their breeding lives.
The young are born relatively mature. They are unusually large and fully furred, and can walk about.
They also have teeth and open eyes at this time. Even though newborn guinea pigs can eat solid food and
drink water from a container, they should be allowed to nurse their mother for at least 2 weeks.
CONDITIONS REQUIRING VETERINARY ATTENTION
Malocclusion of Premolar Teeth (Slobbers)
A common problem of guinea pigs (especially those over 2-3 years old) results when the upper and
lower premolar teeth (the most forward cheek teeth) meet improperly while chewing. In time, this problem
results in abnormal wear of these teeth. This in turn causes entrapment of and continual injury to the
tongue. Affected animals try to eat but cannot chew and swallow food. Drooling results in a continually
moist mouth and chin. Weight loss is often dramatic.
A veterinarian must be consulted as soon as possible if this condition is suspected. The diagnosis is
confirmed upon direct visual examination of the mouth. Correction of the problem involves general
anesthesia and aggressive trimming or filing of the overgrown teeth. This is a difficult procedure because of
the guinea pig’s extremely small mouth opening. Force feedings and antibiotics are usually necessary for a
number of days before and after this procedure has been performed.
There is no permanent solution or correction for this problem. Periodic trimming or filing is almost
always necessary. Guinea pigs with this problem should never be bred so as to prevent passing this most
undesirable trait to their offspring.
Vitamin C Deficiency
(Scurvy or Scorbutus)
Guinea pigs cannot manufacture Vitamin C and must receive an adequate supply of it from outside food
sources. Vitamin C deficiency results in scurvy, which is characterized by inappetence, swollen, painful joints
and ribs, reluctance to move, poor bone and teeth development, and spontaneous bleeding from the gums
and into muscle.
Adequate levels of Vitamin C are always included in the formulation of pelleted diets for guinea pigs.
Often, however, handling and improper storage (exposure to light, heat and dampness) f the feed pellets
results in loss of Vitamin C. Therefore, even guinea pigs fed presumably reliable pelleted diets may develop
scurvy if the diet’s Vitamin C content has been reduced or lost.
A veterinarian should be consulted if this disease is suspected so that the diagnosis can be confirmed.
The veterinarian will prescribe a program of Vitamin C supplementation (via food or water or injection) to
reverse the signs.
Difficulties During Birth
Dystocia: Female guinea pigs intended for breeding must be first bred before 7 months of age. If the
first breeding is delayed beyond this time, serious (sometimes life-threatening) problems with delivery are
encountered.
A portion of the pregnant sow’s pelvis must widen for successful delivery of her young. This separation
fails to develop in females bred for the first time after 7 months of age, usually necessitating a cesarean
section to deliver the young and save the sow’s life.
Signs of dystocia include straining and uterine bleeding. Veterinary help must be sought immediately.
The veterinarian will evaluate the pregnant sow by direct exam and by taking x-rays. If a vaginal delivery of
the young is not possible, a cesarean section will be necessary.
Pregnancy toxemia is a serious condition that usually occurs in overweight sows in their first or second
pregnancy. Signs are most likely to be noted over 105 days during the last 2 weeks of pregnancy or the
first week following birth. These include inappetence, depression, weakness, reluctance to move,
incoordination, difficulty breathing, coma and death. Some afflicted sows may show no signs and suddenly
die.
There is no single cause for this condition, but stress and obesity are major predisposing factors.
Others include advancing age, lack of exercise, fasting just before onset of signs, and a large number of
developing fetuses. The fundamental underlying problem seems to be inadequate blood flow to the uterus.
Sows showing any of these signs must be seen immediately by a veterinarian. Because treatment is
often unsuccessful, prevention of pregnancy toxemia is of paramount importance. Pregnant sows should
not be allowed to become obese. Fasting and stress must be avoided, especially in the last several weeks
of pregnancy. Pregnant sows must be supplied with fresh water at all times and fed a nutritious diet.
Hair Loss
Hair loss or thinning of the hair is a common problem of female guinea pigs that have been repeatedly
bred. Those sows tend to lose hair with each successive pregnancy.
Hair loss is frequently noted among juvenile guinea pigs in a weakened state at or around the time of
weaning. “Barbering” also results in hair loss. This vice (bad habit) occurs when guinea pigs habitually
chew on the haircoats of guinea pigs that are lower in the social “pecking order.” Younger guinea pigs, in
particular, can lose substantial amounts of hair as a result of this activity.
Hair can also be lost because of fungal disease and external parasite infestations.
Heat Stress (Heat Stroke)
Guinea pigs are especially 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, crowding and stress are additional predisposing factors.
Signs of heat stroke include panting, slobbering, weakness, refusal to move about, delirium, convulsions
and eventually death. Heat stroke is treatable if recognized relatively early. Heat-stressed guinea pigs
should be immediately sprayed with or bathed in cool water. Once this first-aid is undertaken, a
veterinarian should be contacted immediately.
Prevention of heat stroke involves providing adequate shade from the sun (if guinea pigs are housed
outdoors) and adequate ventilation (if housed indoors). A continuous light mist or spray of water and/or a
fan operating over a container of ice can be directed at a guinea pig within its enclosure to lower the air
temperature, whether the guinea pig is housed indoors or outdoors.
Cancer
Cancer is a relatively rare problem of guinea pigs. As with most animals, it is most likely to affect older
guinea pigs. Most tumors are benign and involve the skin and respiratory tract lining. Cancer may also
affect the reproductive tract, mammary glands (breasts) and blood (leukemia).
Footpad Infections (Bacterial Pododermatitis)
Serious (sometimes crippling) infections of the footpads are common among pet guinea pigs housed
continuously on wire. The other major predisposing factor is fecal soiling of wire-bottomed enclosures. The
front feet of overweight animals are especially vulnerable to this condition.
Signs include swelling of the feet, lameness, reluctance to move, and inappetence. The flooring of the
enclosure must be changed and overall sanitation must be improved. A veterinarian must be consulted
regarding treatment of affected feet. Topical dressing with an antibiotic and periodic bandaging are
necessary during the usually lengthy recovery period. Injectable antibiotics are often used by veterinarians
in treatment of this condition. Arthritis is a frequent and unfortunate consequence of these infections.
Cervical “Lumps” (Cervical Lymphadenitis)
Abscessation of the lymph nodes immediately beneath the lower jaw, in the upper neck, usually results
when coarse foods (such as hay) injure the lining of the mouth or when superficial wounds penetrate the
skin over these lymph nodes. Bacterial invasion causes painful, swollen abscesses under the lower jaw.
Sometimes these abscesses break open and exude a thick, creamy yellow-white pus.
A veterinarian can perform a bacterial culture of the pus with antibiotic sensitivity testing to determine
the appropriate antibiotic to use by injection. If the abscesses are large, surgical removal and aggressive
antibiotic therapy may be recommended.
Pneumonia
Pneumonia is one of the most common bacterial diseases of pet guinea pigs. A number of potential
disease-causing bacteria may inhabit the respiratory tracts of otherwise normal guinea pigs. Stress,
inadequate diet, and improper home care often predispose a pet guinea pig to respiratory infection. Signs
of pneumonia may include labored or rapid breathing, discharge from eyes and nostrils, lethargy and
inappetence. Some animals show no signs at all before dying suddenly.
Middle and inner ear infections occasionally result from respiratory disease in guinea pigs. Additional
signs may include incoordination, tilting of the head, circling to one side, and rolling.
A veterinarian must be consulted about this serious bacterial infection. Aggressive antibiotic therapy by
injection and appropriate supportive care are necessary. Bacterial culture and antibiotic sensitivity testing
help the veterinarian select an appropriate antibiotic. Unfortunately, even though the signs of infection can
be relieved, the causative bacteria cannot be eliminated.
Rabbits and rats harbor at least one of the bacteria known to cause pneumonia in guinea pigs.
Therefore, it is wise not to house these animals with or near guinea pigs.
Intestinal Infections (Bacterial Enteritis)
Numerous bacteria can cause infections of the gastrointestinal tract of guinea pigs. Some of these
bacteria are introduced on contaminated greens and vegetables or in contaminated water.
Intestinal infections can manifest themselves as sudden death without prior signs, or as a more lengthy
period of illness characterized by lethargy and marked weight loss. Diarrhea may or may not be noted in
either case.
A veterinarian will recommend aggressive antibiotic therapy and appropriate supportive care. A
bacterial culture of the patient’s stool and antibiotic sensitivity testing help the veterinarian select the
appropriate antibiotic.
Ringworm
Ringworm is a skin disease caused by a fungus similar to the one that causes athlete’s foot in people.
Young guinea pigs are usually more susceptible than adults. Ringworm in guinea pigs is generally
characterized by patchy hair loss on the face, nose and ears. The skin in these areas may appear flaky.
Areas of hair loss may extend along the top side of the trunk.
A veterinarian must confirm the diagnosis and prescribe topical and/or oral medication. The medications
to be used depend on the number of ringworm areas present and their distribution on the body.
Ringworm can be transmitted from guinea pigs to people. It is, therefore, important to limit or restrict
handling of infected guinea pigs (especially by young children) until their disease has been successfully
treated. If handling is necessary, the handler should thoroughly wash his hands afterward.
Viral Diseases
Most viral infections of pet guinea pigs are either mild or unapparent.
Lice Infestation
Lice and mites are the most common external parasites of guinea pigs. Lice are tiny, wingless, flattened
insects that live within the haircoat. Both the adults and their eggs are found attached to individual hairs.
Guinea pigs may be parasitized by two types of biting lice. Both abrade the skin surface and feed off of
the body fluids that exude through the very superficial wounds they create.
Light infestations usually go unnoticed. Heavy infestations are usually accompanied with excessive
itching, scratching and some hair loss. Scabs may also be evident around the ears.
A veterinarian can confirm the diagnosis by direct examination of the haircoat. Direct examination is
usually all that is necessary, though use of a microscope is very helpful. The veterinarian will usually
prescribe an insecticidal shampoo to treat affected guinea pigs.
Lice can be transmitted by direct and intimate contact between infested and uninfested guinea pigs.
Therefore, pet guinea pigs are very unlikely to harbor these parasites unless they are recent acquisitions
that were previously in contact with louse-infested guinea pigs. Established pet guinea pigs could also be
infested by being placed in close contact with new, infested guinea pigs. Guinea pig lice do not parasitize
people.
Mite Infestations (Mange)
A mite similar to the scabies mite of people causes serious infestations in pet guinea pigs. Mites are
microscopic, spider-like organisms that live within the outer layers of the skin. They usually cause intense
scratching and significant hair loss. Some cases without scratching have been reported. Some guinea pigs
are so miserable because of the infestation that their constant scratching produces serious wounds. They
may run wildly or in circles, and occasionally even have convulsions.
A veterinarian must do a number of scrapings of the skin to confirm the diagnosis. Successful treatment
consists of 1-4 injections of a specific drug (ivermectin) 10-14 days apart. Any wood shavings within the
enclosure should be replaced by white paper toweling during treatment to help make the patient more
comfortable.
Mites can only be transmitted by direct contact between infested and uninfested guinea pigs.
Established pet guinea pigs could also be infested by being placed in close contact with new, infested
guinea pigs. Guinea pig mites do not parasitize people.
Intestinal Parasite Problems
Intestinal parasites are usually not a significant problem in pet guinea pigs. A protozoan (one-celled
organism) parasite may cause coccidiosis in guinea pigs. Signs of this disease include weakness, diarrhea
and severe weight loss. Pinworm infections of guinea pigs usually go unnoticed.
Both of these parasitisms can be diagnosed by a veterinarian by stool examinations. Both are treatable
using specific drugs prescribed by the veterinarian. Neither parasite problem is transmissible to people.
SENSITIVITY OF GUINEA PIGS TO CERTAIN ANTIBIOTICS
Guinea pigs as a group are unusually sensitive to certain antibiotics, whether they are given orally or by
injection. Potentially harmful antibiotics include ampicillin, penicillin, bacitracin, erythromycin, lincomycin,
gentamicin, clindamycin, streptomycin, vancomycin and sometimes tetracycline. Interestingly, even certain
antibiotics used topically may produce lethal effects.
The major way in which certain antibiotics cause reactions is by altering the normal microbial balance
within the gastrointestinal tract. Once the normal intestinal microfloral balance has been upset, certain
bacterial multiply to abnormally large numbers. The multiplying bacteria produce harmful chemicals that can
have lethal effects.
Certain antibiotics (streptomycin, dihydrostreptomycin) are directly toxic and do not alter the microbial
balance within the gastrointestinal tract. These antibiotics should never be used in guinea pigs.
Though injectable antibiotics can cause the problems described above, oral antibiotics should never be
given to guinea pigs unless they are prescribed by a veterinarian. If oral or injectable antibiotics are
prescribed, 2 ½ cc (1/2 teaspoon) of plain, white yogurt should be given orally to the treated animal morning
and evening for the duration of the antibiotic therapy and for an additional 5-7 days afterward. Yogurt helps
replace those beneficial intestinal bacteria that often perish during antibiotic treatment.
HUMAN ALLERGIES TO GUINEA PIG DANDER
Certain people are allergic to the hair and/or dander of guinea pigs. People working with guinea pigs in
laboratory situations are more likely to develop such allergies because of their continual association with
them. Signs include itchy eyes, sneezing, runny nose, persistent cough, shortness of breath, wheezing,
rash, and anaphylactic shock (a true medical emergency).
Owners of pet guinea pigs may also be susceptible, and a medical doctor should be consulted about
suspected allergy problems if a guinea pig is kept as a pet in the household. Guinea pig owners with such a
suspected allergy may want to sonsult an allergist.
VITAL STATISTICS
Scientific name:
Cavia porcellus
Life span:
3-4 years
Potential life span:
6-7 years
Desirable environmental temperature range:
65-75 F
Desirable relative humidity range:
40-70% (50% is considered ideal)
Recommended age at first breeding:
Males: 3-4 months
Females: 3-7 months
(not after 7 months)
Length of estrous (heat) cycle:
16 days
Length of estrus (period when female is receptive to male):
8 hours
Gestation (pregnancy) period:
Averages 63-68 days
Average litter size:
3-4 young (range, 1-6)
Age at weaning:
2-3 weeks
CLUBS AND ORGANIZATIONS
A wealth of additional useful information may be obtained by joining one or more of the organizations listed
below. All of these groups publish newsletters or bulletins.
American Cavy Breeders Association
(www.acbaonline.com)
c/o Lenore Gergen
16540 Hogan Avenue
Hastings, MN 55033
651-283-0202
McCavy@aol.com
California State Rabbit & Cavy Breeders Association
(www.csrcba.org)
Nancy Hinkston
1311 Poe Lane
San Jose, CA 95130
Jack Pine Guinea Pig Rescue
(www.jpgpr.com)
26515 Apollo Street NE
Stacy, Minnesota 55079
SUGGESTED READING
Harkness and Wagner: The Biology and Medicine of Rabbits and Rodents. 3rd ed. Lea & Febiger,
Philadelphia, 1988.