Health Care for Guinea Pigs

General Information

Guinea pigs are rodents (related to chinchillas and porcupines) that originated from the Andes Mountains region of South America. In the 16th century, Dutch explorers introduced guinea pigs to Europe, at which time selective breeding and captive rearing begin in earnest. These activities have continued to the present.

Guinea pigs are extremely popular pets today because of their availability, docile temperaments, tendency not to bite or scratch when handled, and because of their relatively clean habits. They are not terribly long-lived which can be disconcerting to owners (especially children). Many parents feel that having their children experience the relatively short period of companionship and subsequent death is a favorable and meaningful way to expose children to the "ups and downs" of life.

In their natural habitat, guinea pigs live in open, grassy areas. They prefer to seek shelter in naturally protected areas or within burrows created and later 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 afternoons and early evenings as the daylight wanes.

Handling-Restraint

Guinea pigs rarely violently struggle when they are being picked up but often make their “squeal of protest” which sounds pig-like to many. Nevertheless, great care should be taken not to injure them during this activity. The guinea pig to be lifted 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 careful attention.

One of the most desirable features of guinea pigs as pets is that the rarely bite when being handled or restrained.

Housing

Proper, adequate housing is a major factor in the maintenance of healthy guinea pigs. The psycho-social 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 latter three materials are preferred because they resist corrosion. Wood and similar materials should not be included in the construction of enclosures because they are difficult to clean and these materials cannot withstand the destructive gnawing of the occupant(s). The construction and design of the enclosure must ensure that the resident(s) cannot escape. Furthermore, the enclosure must be free of sharp edges and other potential hazards.

The enclosure must be roomy enough to allow the resident(s) to pursue normal activities and breeding activity, if the latter is desired. One reference recommends at least 100 square inches of floor area per adult “pig”, whereas breeding guinea pigs should be allowed 180 square inches per animal.

The enclosure can be open at the top provided that the sides are at least 7 to 8 inches high. Male guinea pigs (especially breeding males) will require the sides of their enclosure to be at least 10 inches high. They tend to be more rambunctious.

Guinea pigs can be housed on wire mesh (that which is suitable for housing rats can be used) but it is not recommended. Such material will allow urine and most fecal pellets to drop through, there by keeping the bedding and the resident “pig(s)” cleaner. Guinea pigs housed for long periods on wire, however, tend to develop serious injuries to the bottom of their feet. Furthermore, broken legs are quite common when guinea pigs fall through 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 preferred bedding are the best for pet guinea pigs. They should be easy to clean, well lighted and adequately ventilated. Bedding must be clean, non-toxic, absorbent, relatively dust-free and easy to replace. Shredded paper, wood shavings, and processed corn cob are preferred bedding materials. Sawdust should be avoided even though it meets the aforementioned criteria. This material tends to collect within the external genitalia of male “pigs”, 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 similar or perceived stresses. Sudden environmental changes should also be prevented.

Effects of Noise

Guinea pigs exhibit two types of reactions when startled by a loud noise, sudden movement, or strange environment. They may “freeze” completely motionless (for up to 20 minutes) or panic. The latter reaction involves erratic running and leaping, often accompanied with shrill squealing. Groups of guinea pigs will stampede in a circle, often trampling the younger residents within the enclosure. A panic reaction will scatter bedding and food, fouling the food and water containers. Visual security (a place into or under which the resident(s) can retreat when frightened) should always be provided. Rectangular enclosures and the provision of barriers within them will also reduce the tendency to stampede and circle.

Hygiene

The frequency with which the enclosure is cleaned will depend 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 a week. The food and water containers should receive cleaning and disinfection once a day. We suggest more than one set of containers. While one set is being “used” the other set can be disinfected. The containers can be put in the dishwasher, if possible. A vigorous scrubbing of the enclosure and “furniture” with hot water and soap and a thorough rinse should be followed by the disinfectant.

Food and Water

Good quality food and fresh, clean water must be readily available at all times. The exact nutritional requirements of the guinea pig are known and 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 will be tempted to feed rabbit pellets, assuming that they are roughly equivalent to guinea pig pellets. They are not equivalent. 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 receive it from an outside source. 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 to 20% protein, 16% fiber, and approximately 1 gram of vitamin C per kilogram of ration. Even when the fresh pellets are properly stored in a cool, dry place, approximately one half of the vitamin C content is degraded and lost within six weeks of manufacture. Therefore, we recommend that the diet be supplemented with vitamin C as follows: 200 milligrams ascorbic acid (= vitamin C) added to approximately one quart of drinking water, make up fresh every 12 hours, or a single guinea pig should be offered one handful of kale or cabbage or one quarter of an orange daily.

Unlike most mammals (including rabbits), guinea pigs require a high level of vitamin C. Unlike rabbits, guinea pigs cannot manufacture their own vitamin C and must receive it from an outside source. Interestingly, man and his primate relatives share this metabolic inability and dependence on vitamin C from the food that they 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.

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 cautions. These items should not exceed 10 to 15% of what the guinea pig consumes on a daily basis. Furthermore, the fresh items must be thoroughly washed to avoid exposing pet guinea pigs to pesticide residues and possible bacterial contamination.

We recommend that fresh greens and timothy hay be provided daily. Fruit in small amounts can be offered daily. Fresh items must be thoroughly washed to avoid exposing pet guinea pigs to pesticide residues and possible bacterial contamination.

All foods should be provided in heavy ceramic crocks that resist tipping over. The crocks should possess high enough sides 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, it is imperative that all food and water containers be cleaned and disinfected daily.

Guinea pigs tend to be creatures of habit and do not tolerate changes in the presentation of their food and water or changes in the taste, order texture or form of the food itself. Pet owners should avoid making radical changes in the food and water containers used and changes in the food itself should be made gradually. Failure to do so usually results in guinea pigs refusing food and water, which can be disconcerting and dangerous.

Breeding Considerations

The single most important breeding consideration is that female guinea pigs should participate in their first breeding before seven months of age. If the first breeding is delayed beyond this time, serious (sometimes life-threatening) problems with delivery are encountered. Female "pigs" should be first bred between 3 and 7 months of age. Males should be 3 to 4 months old at their first breeding.

The guinea pigs heat cycle last 16 days. The actual period during which the female is receptive to the male and will allow breeding is approximately 8 hours. Female guinea pigs are capable of coming back into heat 6 to 15 hours after giving birth. This is called a "postpartum estrus" which means that they can be nursing a litter and be pregnant at the same time!

Pregnancy last an average of 63 to 68 days. The larger the litter size, the shorter the term and vice versa. The duration of pregnancy for guinea pigs is unusually long when compared with that of other rodents.

Pregnant sows 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 into which their young would otherwise be delivered. The pet owner attending a near term sow will a slowly widening separation of the pelvis just in front of the external genitalia of the pregnant sow within the week prior to delivery. This separation reaches slightly more than 1 inch in the hours just prior to delivery.

This separation of the pelvis fails to take place in females that are bred for the first time after 7 months of age, creating as impossible and tragic situation. Delivery of the young is not possible and a caesarean section must usually be preformed in order to order the life of the sow and her babies.

An uncomplicated delivery usually requires about ½ hour with an average of 5 minutes between babies. Litter size range from 1 to 6 young with 3 to 4 being average. Litters resulting from the first breeding are usually very small. Abortions and stillbirths are common occurrences with guinea pigs throughout their breeding lives.

The young are born relatively developmentally advanced. They are unusually large and fully-furred and capable of walking about. Furthermore, they possess teeth and open eyes at this time. Even though the newborn “pigs” are capable of eating solid food and drinking water from a container, it is recommended that they be allowed to nurse their mother for at least 2 weeks.

Common Conditions Requiring Veterinary Medical Attention

Non-Infectious Conditions

Malocclusion of Premolar Teeth (Slobbers)

A common problem of guinea pigs (especially those over two to three years old) results when the upper and lower premolar teeth (the most forward-positioned of the cheek teeth) meet improperly while chewing. In time, this problem results in abnormal wear of these teeth. This problem results in signs and symptoms that will surely be of concern to the guinea pig owner, desire to eat but inability to chew and swallow food, drooling resulting in a continually moist mouth and chin, and weight loss.

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 filling of the overgrown teeth, a most difficult procedure because of the guinea pig’s extremely small mouth opening. Forced feedings and antibiotics are usually necessary for a number of days before and after this procedure has been performed.

There is no permanent solution of correction for this problem. Periodic trimming/filling is almost always necessary. Guinea pigs with this problem should never be bred in order to prevent passing this most undesirable trait to their offspring.

Vitamin C Deficiency (Scurvy or Scorbutus)

As discussed in the section on Food and Water, guinea pigs (like man) cannot manufacture vitamin C and must receive an adequate supply of it from outside food source. Failure to do so results in scurvy, the symptoms of which include in appetence; swollen, painful joints and ribs; reluctance to move; poor bone and teeth development and spontaneous bleeding from the gums and into muscle.

This mandatory vitamin C requirement is well known to those who manufacture the pelleted diets for guinea pigs and adequate levels of this vitamin are always included in the formulation of them. Often, handling and improper storage (exposure to light, heat and dampness) of these pellets results in loss of potency of the vitamin C. Therefore even pet guinea pigs fed presumably reliable pelleted diets may exhibit signs of scurvy if the potency of the vitamin C within them has been reduced or lost.

A veterinarian should be consulted if this disease is suspected so that confirmation of the diagnosis can be made. Furthermore, the veterinarian will need to prescribe a program of vitamin C supplementation (via food or water or injection) in order to reverse the symptoms.

Difficulty with Delivery of Young (Dystocia)

Signs of dystocia include straining and uterine bleeding. An owner of a guinea pig exhibiting these symptoms must seek veterinary help 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, then a caesarean section will be advised.

Pregnancy Toxemia

Pregnancy toxemia is a serious condition of usually overweight sows most often in their first or second pregnancies. Symptoms of these conditions are most likely to be noted within the last two weeks of pregnancy or the first week following same and include: in appetence, depression, weakness, reluctance to move, in coordination, difficulty breathing, coma, and death. These symptoms may be noted over a one to five day period. Some afflicted sows may show no symptoms 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 prior to onset of symptoms, and a large number of developing fetuses. The fundamental underlying problem appears to be an inadequate blood flow, and hence, nutrient supply, to the pregnant

Pregnant sows or those which have recently delivered that exhibit any of the aforementioned symptoms must be seen immediately by a veterinarian. Treatment is directed towards reversing the low blood sugar, acidic pH of the blood and accumulation of ketones within it, but such attempts are often unsuccessful.

Prevention of pregnancy toxemia is of paramount importance. Pregnant sows should be prevented from becoming obese. Fasting and stresses of all kinds must be avoided, especially in the last several weeks of pregnancy. Pregnant sows must be supplied with fresh water at all times and 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. These 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. The vice (bad habit) occurs when guinea pigs habitually chew on the hair coats of "pigs" that are lower in the social "pecking order". Younger guinea pigs, in particular, can lose substantial amounts of hair as a result of the activity.

Heat Stress (Stroke)

Guinea pigs are especially susceptible to heat stroke, particularly those that are overweight or heavily furred. Environmental temperatures above 85 degrees Fahrenheit, high humidity (above 70 percent), inadequate shade and ventilation, crowing and physiological stress are additional predisposing factors.

Signs of heat stroke include panting, slobbering, weakness and refusal to move about, delirium, convulsions and eventually death. Heat stroke is a treatable condition if recognized relatively early. Heat-stressed guinea pigs should either be sprayed with cool water or be bathed in cool water. Once this first aid measure is undertaken, a veterinarian should be contacted immediately.

Prevention of heat stroke involves of heat stroke involves providing adequate shade from the sun (if guinea pig(s) are house outdoors) and adequate ventilation (if guinea pig(s) are housed indoors). Furthermore, a continuous light mist or spray of water or a fan operating over a container of ice can be directed at a guinea pig within its enclosure in order to lower the air temperature, whether the guinea pig is housed indoors or outdoors.

INFECTIOUS CONDITIONS

Bacterial Infections

Footpad Infections (Bacterial Pododermatitis). Serious (sometimes crippling) infections of the footpads are extremely 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 "pigs" are especially vulnerable to this condition.

Symptoms of this condition include swelling of a foot (of the feet), lameness, reluctance to move, and inappetence. The flooring of the enclosure must be changed and overall sanitation must be improved. Furthermore, a veterinarian must be consulted regarding treatment of the affected foot (feet). Topical dressing with an antibiotic and periodic bandaging will be necessary during the usually lengthy recovery period. Injectable antibiotics are often used by veterinarians in the treatment of this condition. Arthritis is a frequent and unfortunate consequence of these infections.

Cervical "Lumps". Abscesses of the lymph nodes immediately beneath the lower jaw in the upper neck usually results when coarse foods (such as hay) cause injury to the lining of the mouth or when superficial wounds penetrate the skin over these lymph nodes. In both cases, bacterial invasion is permitted. Symptoms include firm, painful swelling under the lower jaw. Sometimes these abscesses break open, allowing a thick, creamy yellow-white pus to issue forth. If the abscesses are large, complete surgical removal of them will be recommended along with aggressive antibiotic therapy.

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. Conditions of stress, inadequate diet, and improper home care will often predispose a pet guinea pig to an opportunistic infection with one or more of these bacteria. Symptoms of pneumonia may include labored or rapid breathing, discharge from eyes or nostrils, lethargy and inappetence; or no symptoms at all with sudden death.

Intestinal Infections. A number of bacteria are capable of causing infections of the gastrointestinal tract of guinea pigs. Some of these bacteria are introduced on contaminated greens and vegetables or in contaminated water.

There appears to be two major ways in which these intestinal infections manifest themselves: sudden death without obvious prior symptoms or a more lengthy period of illness characterized by lethargy and marked weight loss. Diarrhea may or may not be noted in either case.

Ringworm. Ringworm is a skin disease caused by a fungus. 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. The areas of hair loss may extend along the top side of the trunk of affected guinea pigs.

Transmission of ringworm from guinea pig to man is very possible. It is extremely important to limit or restrict handling of ringworm-infected guinea pigs (especially by young children) until their disease has been successfully treated. If handling of affected guinea pigs is necessary, the handler should thoroughly wash his hands afterwards.

Parasitic Disease

External Parasite Problems

Lice Infestation. 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 the animals they parasitize. In fact, both the adults and their eggs are found attached to individual hairs of the hair coat.

Light infestations usually go unnoticed. Heavy infestations are usually accompanied with excessive itching, scratching and some hair loss. Scabs may also be evident on and around the ears.

Mite Infestations. Mites are microscopic, spider-like organisms that live within the top layers of the skin. Their presence in this location usually cases intense itching, scratching and significant hair loss. Some cases without itching and scratching have been reported. Some guinea pigs are so miserable because of the infestation that they will produce serious self-inflicted wounds and exhibit wild running and circling and occasionally, even convulsions.

Treatment consists of an injection to kill the mites. Guinea pig mites do not parasitize man.

Intestinal Parasite Problems

Intestinal parasites are usually not a significant problem in pet guinea pigs. Symptoms of this disease include weakness, diarrhea and severe weight loss.

A Special Comment Regarding The Extreme Sensitivity of Guinea Pigs To Certain Antibiotics

Guinea pigs as a group are unusually sensitive to the potentially lethal effects of certain antibiotics, whether they are given orally or by injection.

The major mechanism for this often lethal effect of certain antibiotics is the tremendous alternation that these drugs can cause to the normal microbial balance within the gastrointestinal tract.

General Information About Guinea Pigs

Scientific Name Cavia Porcellus

Life Span 3 - 4 years

Potential Life Span 6 - 7 years

Desirable Temperature Range 65 - 75 Degrees Fahrenheit

Desirable Humidity Range 40 - 70 percent (50 percent is considered ideal)

Recommended Age at First Breeding Male: 3 - 4 months
Female: 3 - 6 months (not after 6 months)

Length of Estrous (Heat) Cycle 16 days

Length of Estrus (period during which female is receptive to male for copulation) 8 hours

Gestation (pregnancy Period) Averages between 63 & 68 days

Average Litter Size 3 - 4 young (range 1 - 6)

Age at Weaning 2 - 3 weeks