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The Guinea Pig

The Guinea Pig

The guinea pig is a very popular small mammal. It is a herbivore belonging to the order of rodents and the family of hystricomorphs. It can be distinguished from rabbits, as it has only one pair of maxillary incisors, and it differs from myomorphs (rats, mice, hamsters) with its teeth, all of which are continuously growing. Thus, the problem of dental malocclusion is one of the main reasons for consulting a veterinarian. It is a predominantly diurnal animal, with a lifespan of about 6 years. The female must be mated before 8 months of age if she is to be used as a breeder. In fact, the pubic symphysis merges around the age of 8 months in females that have never given birth. This prevents the pelvis from adapting and widening in preparation for giving birth, causing dystocia (difficulty in giving birth).


As guinea pigs are herbivorous, they must be given hay at will. Alfalfa hay is acceptable for immature young guinea pigs (3 weeks to 3 months) and gestating females, as these individuals need more calcium in their diet. However, this isn't the case for adult guinea pigs. Alfalfa hay may cause the formation of urinary calcium stones, resulting in blood in the urine, discomfort and consequently a loss of appetite. It is therefore advisable to offer the adult guinea pig Timothy's hay, also known as timothy grass. The second most important food in the guinea pig's diet is not kibble, but vegetables. The guinea pig should be fed 1 to 2 cups of various vegetables per day. Among the vegetables to be given every day are collard greens, kale, Romaine lettuce, Swiss chard, bok choy, carrot leaves, turnip greens and endive. Spinach, broccoli (leaf and flower), rhubarb and parsley should be offered no more than twice a week as they contain a lot of calcium. Dandelion leaves and flower are also acceptable. Since carrots are particularly sweet, it is recommended that they be considered a treat (given twice a week). It is also essential to introduce any new food into a guinea pig's diet gradually: too sudden changes can cause diarrhea and even enterotoxemia, a fatal condition. Finally, feed should not be given more than 3 tablespoons per guinea pig, per day. It must be understood that it is optional in the guinea pig's diet and that its consumption in high quantities causes excess weight which favours pododermatitis (infection under the legs) and a decrease in the consumption of hay, causing gastric stasis. Fruit should be offered in smaller quantities, as they are sweeter.


The guinea pig has the unusual characteristic of being unable to produce vitamin C. It is therefore essential to add vitamin C to its food on a daily basis, even if fresh vegetables and fruits that are full of vitamin C are provided to the guinea pig. In fact, the vitamin C in foods tends to degrade very quickly once exposed to the air. Supplements in tablet form are available on the market. It is recommended that they be crushed and sprinkled on a moist food (vegetable), rather than placed in drinking water, because vitamin C oxidizes quickly in contact with water. It may also change the taste of the water and reduce the guinea pig's consumption, risking dehydration.


Several females can share the same cage, unlike males who can display territorial aggressiveness. The cage should be equipped with several hiding places (PVC tubes, cardboard box) in order to reduce stress for your guinea pig. The room temperature should be between 18 and 26 degrees Celsius. If it is higher, the guinea pig may suffer from heat stroke. The recommended bedding is compacted recycled paper as it is not very dusty, whereas cedar and pine litter is known to be irritating to both the skin and the respiratory tract. The guinea pig cannot live with the rabbit since they are both carriers of bacteria that are harmful to each other. The rabbit is a natural carrier of bordetella bronchiseptica, a bacterium that causes respiratory infections in guinea pigs; while the guinea pig is a carrier of Pasteurella Multocida, a bacterium that causes respiratory infections, ear infections and skin abscesses in rabbits. Rabbits and guinea pigs are therefore not a good match.

Frequent Illnesses

Body Mites

Trixacarus Caviae is a body mite affecting guinea pigs. Unlike lice, this parasite can be transmitted to other animals and humans, causing red patches at the site of contact and itching. Treating the guinea pig is usually sufficient to stop the problem, as the parasite only survives long-term in this species. Lesions affecting humans will then disappear on their own, depending on their severity. On the other hand, some more sensitive people may also need treatment. Infested guinea pigs will have a lot of dandruff on their backs and severe itching, sometimes resembling a convulsion. The diagnosis is made with the identification of the mite under the microscope and the treatment is similar to that for pediculosis.

Sarcoptes Scabei is another body mite that affects guinea pigs and other animals. However, this mite is able to live long term in all species, so all affected individuals must be treated to completely eradicate the infection. The infected animal will have multiple hairless areas, scabs, and severe itching. Diagnosis and treatment are the same as for Trixacarus caviae.


Enterotoxemia is a serious digestive condition. It is caused by the growth of bacteria that are not normally present in the guinea pig's intestine. These bacteria produce toxins that will enter the bloodstream and cause shock. The affected guinea pig will show the following clinical signs: severe and sudden despondency, rapid and/or exaggerated breathing, and dark red gums.

Unfortunately, there are numerous causes for the development of bacteria in the guinea pig's intestine: inadequate oral antibiotics, drastic changes in diet, gastric stasis, etc. This condition is suspected during a general examination of the guinea pig and is confirmed with an X-ray of the abdomen. Rapid implementation of treatment is essential to slow the progression, but it only proves to be effective when initiated at the very beginning of the condition. It requires hospitalization in order to provide care via intravenous access.


Guinea pigs are susceptible to fleas affecting cats and dogs. Most affected individuals will not show clinical signs unless they are allergic to the flea's saliva. In this case, each flea bite will be very itchy and the animal will show compulsive scratching, which can even lead to skin lesions and secondary bacterial infections. Guinea pigs should be treated in the same way as cats and dogs, i.e., by applying a vial of Advantage for kittens on the skin of the neck once a month for 4 months.

Gastric Stasis

The guinea pig's digestive system is heavily reliant on a high fibre intake. An inadequate diet (too much feed, insufficient hay), stress, or any other health condition leading to anorexia (urinary stones, uterine tumour, pasteurellosis, dental abscess, etc.) may cause a slowdown in digestive transit. In doing so, food spends more time than normal in the stomach, forming a plug made up of compacted food and hair. This can interrupt normal intestinal movement, causing abdominal distension and pain.

Guinea pigs suffering from gastric stasis will show symptoms such as loss of appetite, a decrease in the volume of stools, and an abnormally calm behaviour. A particularly ailing guinea pig may grind its teeth or adopt a particular position: it lies down so that its entire belly is in contact with the ground (frog-like position).

Thus, a simple physical examination allows us to suspect this condition, to be confirmed by an abdominal X-ray. Treatment should be started promptly after clinical signs appear, to prevent digestive obstruction and the need for surgery. To treat gastric stasis, the animal must be rehydrated, digestive transit must be stimulated with certain drugs, and assisted feeding (force-feeding) and analgesics must be provided. Antibiotics are also an integral part of the treatment, since this condition leads to increased fermentation of food in the intestine, which encourages the exaggerated growth of certain bacteria normally present in smaller quantities.

Although there is a treatment for gastric stasis, the cause of its occurrence must be investigated to prevent recurrence. An assessment of your guinea pig's welfare can be made with your vet, as well as some tests to detect potentially responsible medical conditions.

Ovarian Cysts

Ovarian cysts are a condition found in 88% of female guinea pigs over 2 years of age. This cyst leads to an overproduction of sex hormones which will cause variable clinical signs such as hair loss on both flanks, itching, vaginal discharge, lethargy, and loss of appetite. The diagnosis is made by means of an X-ray. In some cases, when the cysts are smaller and subtler, ultrasound may be necessary. The treatment of choice is sterilization, as the problematic ovary is then removed; otherwise a lupron injection may be used. The latter treatment is more suitable for older guinea pigs, as it usually prevents the cyst from increasing in size and the clinical signs from appearing. However, some individuals do not respond adequately to medication and surgery may become necessary. It should also be noted that a very large cyst will need to be drained under ultrasound so as not to interfere with the function of other organs which could be crushed by the cyst. The injections of lupron will have to be repeated at different intervals, which may vary from one individual to another.


Pediculosis is a lice infestation. Rest assured, the 3 types of lice observed in guinea pigs are species-specific, i.e., they only affect guinea pigs. However, it is important to keep handling the animal to a minimum, as touching it can increase the level of itching. The affected guinea pig will have a greasy, yellowish coat and will frequently develop scabies on the body as a result of excessive scratching.

Diagnosis is made by visualization of the lice and treatment consists of 2 injections of ivermectin administered 1 week apart. Some heavily infected individuals will require additional treatment. Finally, the environment must be disinfected in order to avoid recurrence.

Pneumonia and Respiratory-Ocular Tract Infections

Guinea pigs are susceptible to infections caused by the bacteria Streptococcus Pneumoniae and Bordetella Bronchiseptica, the latter being commonly referred to as “kennel cough” in dogs. This bacterium can affect both dogs and guinea pigs, which means that it is imperative to separate the two animals in the household when a Bordetella Bronchiseptica infection is suspected.

The transmission can be made by direct contact (nose to nose) or indirect contact (petting by the owners, use of the same blanket or bowl of water). The risk of contamination can be reduced by isolating the animals in separate rooms and by taking care to wash your hands thoroughly after each handling. Factors that may promote infection such as air drafts (typically during air changes in autumn and spring, even if it appears to be warm enough), or the proximity of the cage to a window in winter or to the air conditioner/fan in summer should also be avoided.

The incubation period lasts on average 5 to 7 days and clinical signs will vary according to the severity of the infection. Some animals will not develop the disease, but will remain carriers. They may then develop the disease later, for example when the immune system becomes weakened or during periods of stress. If they never develop the infection, they are still potential contaminants. The disease manifests itself as conjunctivitis (red, swollen, closed eyes, yellow-green discharge), rhinitis (yellow-green nasal discharge, noisy breathing, frequent sneezing) or pneumonia (rapid, shallow breathing, with pronounced movements on the sides). In all cases, the guinea pig may show a loss of appetite, be more despondent, or be still in its cage. In all cases, it is important to consult as soon as possible to diagnose and treat the condition before complications arise (gastric stasis, death from pneumonia). The disease can also spread to several organs when treatment is delayed and conjunctivitis can develop into pneumonia in less than 5 days.

The diagnosis will be made according to the affected organ. First of all, a good eye examination must be carried out to detect the presence of conjunctivitis, as well as a complete physical examination. A bacterial culture may be necessary in cases of rhinitis; X-rays of the lungs may be taken when breathing difficulty is noted or when pulmonary auscultation appears abnormal.

The treatment involves the administering antibiotics (either orally or in the form of an eye drop/cream). Force-feeding is also essential if the guinea pig stops eating on its own. The prognosis varies from good to reserved, according to the severity of the infection and the organ affected. Because pus in guinea pigs tends to be thicker, the ability of antibiotics to penetrate the lungs is reduced and the chances of complete resolution are also reduced.


Pododermatitis is an infection or inflammation of the skin under the legs. It is usually more pronounced on the hind legs and is frequently associated with obesity; it can also be secondary to trauma caused by wire cage bottoms. Litter made from pine or cedar shavings can also irritate the skin, promoting pododermatitis.

Treating pododermatitis can take some time and requires the owner's patience. An antibiotic cream is used to address the bacterial infection. Hydrotherapy, on the other hand, promotes cell renewal to heal ulcerations. The animal must be resting in the cage for a variable period of time, depending on the extent of the ulceration and the speed of tissue healing. Subsequently, exercise becomes the key to treatment since obesity is often the cause and weight loss will reduce the risk of recurrence.

The animal's appetite should be monitored during treatment: pain often causes anorexia, which can lead to gastric stasis. Finally, correction of the environment is crucial: removal of wire mesh surfaces and cedar or pine litter. Recurrences are common in pododermatitis, so you should frequently monitor the underside of your pet's legs to detect the onset of inflammation as early as possible.


In guinea pigs, ringworm is caused by a fungus, Trichophyton Mentagrophytes. It causes the appearance of round, hairless patches that tend to enlarge. This fungus can also infect humans by causing red patches on the skin at the site of contact, often associated with itching. To diagnose this fungus, a few hairs are removed from the periphery of the lesions and placed on a culture medium. Handling of the animal and movement in its environment during treatment should be limited. It is important to wear gloves when handling the animal during treatment. Ringworm is treated with a medicated cream applied to the affected areas. Oral medication may also be required depending on the extent of the lesions. The environment should be disinfected with Imaverol in a 1:50 dilution.


Scurvy is a vitamin C deficiency. It is a condition commonly found in guinea pigs that do not receive a supplement or vitamin C. Unlike us, guinea pigs are unable to synthesize vitamin C, so they must be given a daily supplement, even if their feed and fresh vegetables include the vitamin. In fact, vitamin C quickly degrades on contact with oxygen, so any ingredient exposed to the open air quickly loses its vitamin C content. Affected guinea pigs will have dry, dull hair that falls out easily, reduced growth (in young individuals), weakness in the rear limbs, swollen joints, lethargy, diarrhea, and blood in the urine. The diagnosis is made primarily with the presentation history, X-rays or blood tests, depending on the organs affected. Scurvy can be treated with adequate vitamin C intake, but the treatment's success depends heavily on the severity of the deficiency and the lesions already present, as these are mostly irreversible.


If your guinea pig requires medical care that cannot be performed in your hospital, we will transfer its file to our specialized team working the Centre Vétérinaire Laval.