According to AVMA’s 2012 U.S. Pet Ownership & Demographic Sourcebook, guinea pigs are the second most popular small mammal pet; approximately 847,400 US households reported having at least one (hamsters were #1 with 877,000 households). Guinea pigs, or ‘cavies’ as they are also known, are popular pets because of their friendly and unique personalities, they are long-lived (by rodent standards), and they are fairly easy to care for, making them excellent pets for older children.
Guinea pigs were originally domesticated as far back as 5000 BC by the Incas in the South American Andes; they were most likely used as food, but they also to this day hold a hallowed place in indigenous folklore and rituals. Their docility and adorable portly form were most likely due to generations of breeding for the table; European sailors returned to England in the 1600s with a few specimens where they became popular pets with aristocrats. In the early 1900s, British immigrants brought them to the US.1
Cavia Porcellus’ wild relatives live in the cool mountains on grassy plains in abandoned burrows or tunnels formed by vegetation in family groups of up to 10 animals consisting of several females, one male, and offspring. They eat a diet of wild grass and other vegetation, and are most active during dawn and dusk.2 As a result of their ancestry, modern guinea pigs have specific dietary and habitat requirements to stay healthy and happy. Illness or injury due to malnutrition or unclean habitat is the most common causes of guinea pigs presenting for a veterinary visit.
Feeding guinea pigs a proper diet is extremely important. Owners should provide continuous access to hay as it is imperative for their digestion and dental health. Guinea pigs’ incisors grow continuously; their teeth can easily overgrow without access to hard fiber to wear down the teeth.3 Commercial pellet food specific for guinea pigs should be the primary food source, with the addition of fresh produce for enrichment.
A major dietary consideration is adequate intake of vitamin C. Guinea pigs are not capable of manufacturing vitamin C on their own, so supplementation is required. Good dietary sources (“treats”) of Vitamin C for guinea pigs include red or green peppers, tomatoes, spinach, and asparagus. 4 Most commercial foods are supplemented, but exposure to air, humidity, heat, and light quickly cause oxidation and loss.3,4 Monument Pharmacy can easily special order Oxbow brand vitamin C supplements made specifically for guinea pigs, and conveniently ship them directly to the pet owner. A standard daily maintenance dose of vitamin C for guinea pigs is 10mg/kg (30mg/kg if pregnant). 4
If an owner brings in a guinea pig showing signs of diarrhea, alopecia, or joint pain, or the animal appears thin or unkempt, vitamin C deficiency should be considered. Petechia on mucous membranes are not always visible, though hematuria may be present.4
Additional nutritional problems in guinea pigs include metastatic calcification, which usually presents in animals over 1 year of age as muscle stiffness and failure to thrive. Mineral deposition is caused by low-magnesium and high-phosphorus diet, and high calcium and/or high vitamin D intake. The availability of commercially made, high-quality, guinea-pig specific diets has reduced the incidence seen in laboratory colonies. Muscular dystrophy of skeletal muscle or myocardium is associated with a vitamin E/selenium deficiency, and unfortunately is often asymptomatic. Owner education on proper nutrition and selection of a high-quality diet is important to ensure guinea pig health. 4
Guinea pig cages should have a hard floor and be at a minimum two by three feet (many cages at pets stores marketed for guinea pigs are not big enough!). Wire mesh walls ensure proper ventilation. Cavies also require a box or shelter to hide in. Paper pulp is preferred for bedding as it is absorbent, dust-free, and widely available. Bedding should be changed every few days to prevent accumulation of wastes, and the cage itself should be cleaned out weekly with diluted soap and water. Water bottles should be washed daily to minimize bacterial growth. As their wild ancestors are from the high mountains, cavies prefer cooler temperatures and can overheat easily in hot, humid weather. Guinea pigs tend to be social animals and thrive in groups of two or more (usually multiple females, or a neutered male and females), and live on average 5-7 years. 3,4
In habitats with wire or abrasive floors and poor sanitation, chronic dermatitis (especially of the forepaws) may occur. Straw and awns (husks) in the bedding can cause foot punctures, exacerbating symptoms and risk of infection. Symptoms include swelling and hair loss of the feet, with ulcers and scabs on the plantar surface. Staph aureaus is the usual pathogen. Topical or parenteral antibiotic therapy may be warranted, but is not always successful. 4
Guinea pigs are generally healthy pets, but can be prone to upper respiratory infections. They should not be housed with rabbits, cats or dogs due to risk of physical harm and transmission of disease. If a guinea pig presents with oral abrasions, unilateral swellings in the neck, sneezing, dyspnea, wheezy breathing, nasal discharge, coughing, or conjunctivitis, infection is likely. Streptococcus equi, Streptococcus pneumoniae, B bronchiseptica (usually observed secondary to exposure to rabbits), and Chlamydia caviae are frequently encountered pathogens. 4
Salmonella infections were historically common in guinea pig colonies due to contaminated feed, but is rarely encountered now due to improved husbandry standards and quality feeds. Diarrhea is rarely present, and clinical signs include fever, lethargy, anorexia, rough fur, and conjunctivitis.4
Guinea pigs are also affected by parasites including lice and sarcoptid mites, which cause Mange; signs of infestation include intense pruitus, and alopecia. Parenteral ivermectin is frequently recommended for treatment along with a dermal treatment. 4,5
Dermatophytosis (tinea or ringworm) is common in guinea pigs, and usually presents as broken hairs with circular, scaly alopecia starting at the tip of the nose, spreading to the forehead and pinnal areas. High temperature and humidity may contribute to a more severe infection, and treatment is recommended to minimize spread to other animals and humans. Curing the infection in the pet while simultaneously decontaminating the environment is highly recommended. Environmental control should be performed every 14 days with chlorine bleach dilutions, and systemic therapy of itraconazole or terbinafine with or without topical treatment for 4-8 weeks. Often, infections require 2 to 3 months of therapy. 4,5
Guinea pigs are LETHALLY sensitive to antibiotic therapy. Oral and topical therapeutic agents reported to cause enterotoxemia include penicillin, ampicillin, bacitracin, erythromycin, spiramycin, streptomycin, lincomycin, clindamycin, vancomycin, and tetracycline4 Trimethoprim-sulfamethoxazole, chloramphenicol, and enrofloxacin are considered safe to use in guinea pigs. Narrow-spectrum antibiotics with activity against gram-positive bacteria should be avoided; they are lethal as they destroy gram-positive flora, which allows overgrowth of gram-negative flora and leads to bacteremia/septicemia.
When well cared for and properly fed, guinea pigs are generally very healthy animals. They are robust and long-lived by rodent standards and require little care, thus making great pets for children. Their unique personalities and vocalizations make them cherished animal companions. In the unusual event of illness, Monument Pharmacy is here and ready to compound many prescription medications for cavies in a customized dose and a variety of palatable oral suspensions. Currently available agents include:
- Chloramphenicol palmitate
- Oxbow Vitamin C Supplement (commercial)
- Morales, Edmundo. The Guinea Pig: Healing, Food, and Ritual in the Andes. University of Arizona Press, 1995.
- Wagner, Joseph E.; Manning, Patrick J.The Biology of the Guinea Pig. Academic Press, 1976.
- Alexander, Lyssa DVM. Tips for Keeping Guinea Pigs Happy and Healthy. The Ann Arbor News: 14 January, 2011. accessed online http://www.annarbor.com/pets/ask-the-veterinarian-guinea-pig-guide/
- Kahn, Cynthia, et al. The Merck Veterinary Manual (10th Edition). Whitehouse Station, NJ: Merck & Co, Inc., 2010
- Plumb, Donald C. Plumb’s Veterinary Drug Handbook, 10th Ed. Stockholm, WI: Pharmavet, Inc., 2008