Guinea Pigs Are Social Animals — Never Keep One Alone
Guinea pigs, also known as cavies, are highly social creatures that live in groups in the wild. Keeping a guinea pig alone causes genuine psychological suffering — isolated cavies frequently develop depression, lethargy, and stress-related behaviours. The RSPCA and most European animal welfare bodies are clear: guinea pigs must be kept in pairs or small groups. If you already have a single guinea pig, finding a compatible companion is one of the most important steps you can take for their wellbeing.
Before housing guinea pigs together, it is essential to determine their sex to avoid unwanted pregnancies. Male guinea pigs are called boars and female guinea pigs are called sows. To sex a guinea pig, gently support the animal on its back and examine the genital area. Boars have a visible penis that protrudes when gentle pressure is applied above the genital opening, and their scrotal area is visible. Sows have a Y-shaped vulval opening. If you are uncertain, ask your vet or an experienced exotic animal handler to confirm sex before housing animals together.
Lifespan and Long-Term Commitment
Guinea pigs typically live between 4 and 7 years, with some individuals reaching 8 years or more. This is a meaningful long-term commitment. Before acquiring guinea pigs, consider whether your living situation, budget, and lifestyle can accommodate their care over this period, including veterinary costs for conditions that become more common in older animals.
Housing: Space, Temperature and Safety
The RSPCA recommends a minimum floor space of 4 square feet per guinea pig, though more is always better. Many commercial cages sold in pet shops fall short of this standard. A hutch or enclosure measuring at least 120cm x 60cm for a pair is a reasonable starting point, but larger runs and enclosures significantly improve welfare.
Guinea pigs can be kept indoors or outdoors, but temperature is critical. They are sensitive to cold and heat alike. Their comfortable temperature range is approximately 15°C to 25°C. Do not house guinea pigs in temperatures below 15°C — they cannot hibernate and cold exposure leads to respiratory illness and hypothermia. Equally, temperatures above 25°C risk heatstroke. Outdoor hutches must be positioned away from direct sunlight, raised off the ground to prevent damp, and fully draught-proof. In winter, outdoor guinea pigs in the UK and Northern Europe should ideally be moved indoors or to a well-insulated shed.
Avoid barred or wire flooring as this causes foot injuries. Solid, smooth flooring with appropriate bedding is essential.
Bedding: What Is Safe and What to Avoid
Hay is the foundation of good guinea pig bedding and should always be available in abundance. Safe paper-based bedding materials are appropriate for the living area. Avoid pine and cedar wood shavings entirely — these contain phenols, aromatic compounds that are toxic to guinea pigs and can cause respiratory damage and liver problems. If you use wood shavings, only kiln-dried aspen shavings are generally considered safer, though paper-based bedding remains the preferred choice.
Diet: Hay, Vegetables and Pellets
Hay must make up approximately 80% of a guinea pig's diet. It provides the fibre essential for digestive health and the constant chewing action needed to wear down continuously growing teeth. Timothy hay is suitable for adult guinea pigs; alfalfa hay is higher in calcium and more appropriate for young or pregnant animals.
Fresh vegetables should be offered daily. High-quality pellets can supplement the diet but should not replace hay or fresh vegetables. Look for pellets that are plain and uniform in shape — avoid mixed seed and nut blends, as guinea pigs selectively eat the high-sugar components.
Vitamin C: A Critical Requirement
This is one of the most important facts every guinea pig owner must understand. Guinea pigs, like humans, cannot synthesise their own Vitamin C. They must obtain it entirely through their diet. Vitamin C deficiency causes scurvy, which leads to weight loss, swollen and painful joints, bleeding gums, poor wound healing, rough coat, and eventually death.
The best way to provide Vitamin C is through fresh vegetables. Red and green peppers are exceptionally high in Vitamin C and are very well accepted by most guinea pigs. Other good sources include kale, parsley, broccoli, and dark leafy greens. Offer a varied selection daily.
Do not rely on pellets alone for Vitamin C. Vitamin C is highly unstable and degrades rapidly — by the time pellets reach your home and are stored, much of the Vitamin C content may already be lost. Vitamin C added to water also degrades within hours. Fresh vegetables are the reliable source.
Common Health Conditions
Scurvy
As described above, Vitamin C deficiency is common in guinea pigs fed inadequate diets. Signs include reluctance to move, swollen legs, dental problems, and weight loss. Treatment involves Vitamin C supplementation under veterinary guidance alongside dietary improvement.
Bumblefoot (Pododermatitis)
Bumblefoot is a painful bacterial infection of the feet, often caused by wire flooring, damp bedding, or obesity. The feet become swollen, red, and ulcerated. Prevention through appropriate solid flooring and clean, dry bedding is key. Veterinary treatment with antibiotics and wound care is required.
Respiratory Infections
Bordetella bronchiseptica is a common bacterial cause of respiratory infections in guinea pigs. Signs include nasal discharge, sneezing, laboured breathing, and lethargy. Prompt veterinary attention is necessary as respiratory infections can deteriorate quickly.
Dental Malocclusion
Guinea pig teeth grow continuously throughout their lives. If the teeth become misaligned, they overgrow and can prevent the animal from eating. Signs include drooling, weight loss, and difficulty chewing. Regular hay consumption helps wear teeth naturally, but some animals require veterinary dental treatment.
Ovarian Cysts in Sows
Ovarian cysts are extremely common in older female guinea pigs, particularly those that have not been spayed. They frequently cause bilateral hair loss along the flanks, aggression, and behavioural changes. Diagnosis is by ultrasound. Treatment options include hormonal injections, drainage, or surgical spaying.
Mites (Trixacarus caviae)
Guinea pig mange mites cause intense itching, hair loss, and skin crusting. Affected animals may appear to have seizures due to the severity of the pruritus. This is highly treatable with antiparasitic medication from your vet. Any guinea pig showing severe scratching should be seen promptly.
Handling and Behaviour
When picking up a guinea pig, always support their full body with both hands. Unlike cats, guinea pigs cannot land safely if dropped and fall injuries can be fatal. Children must be supervised and taught correct handling technique.
Guinea pigs communicate through a range of sounds. A high-pitched wheek or whistle signals excitement or anticipation, often at meal times. Purring indicates contentment during gentle handling. Teeth chattering is a warning sign — the animal is stressed or feeling threatened and should be given space.
Vaccination and Veterinary Care
Guinea pigs do not require routine vaccinations in the UK or most of Europe. However, regular veterinary check-ups are still important, particularly as your guinea pigs age. Finding a vet experienced with exotic animals or small mammals is strongly recommended — not all general practice vets have extensive cavy expertise. An exotic animal vet will be better equipped to identify dental problems, ovarian cysts, and other conditions common in guinea pigs.