Rex Guinea Pig

Is a Rex guinea pig right for you?

The Rex guinea pig carries a mutation that removes the long guard hairs other breeds have. The result is a dense, velvety coat no more than about 1 cm long that stands straight out from the body — often compared to the feel of a hedgehog's coat. This short coat removes the daily-brushing requirement long-haired breeds need, but the Rex still asks for its own attention: its nails grow faster than in other guinea pig breeds, and because a short coat gives less natural protection than a long one, skin checks should not be skipped.

The two most critical points: a guinea pig cannot make its own vitamin C, and a Rex must never be kept alone. A short coat does not mean "no grooming" — regular nail and skin checks are still required.

Before you adopt

A guinea pig should always be planned as at least two animals. Two females, or a neutered male with a female, are compatible pairings. Prefer a shelter or rehoming group over a shop purchase.

When assessing a Rex guinea pig:

• Coat: short, dense, and standing upright is the healthy look; it should be shiny with no obviously bald or thinned patches. Noticeable local hair loss can be a sign of illness, not a normal breed trait.
• Skin: part the coat and look; redness, crusting, dandruff, or intense itching may point to fungus or parasites.
• Nails: overly long or curled nails are a sign of neglected care.
• General condition: bright eyes, a dry nose, quiet breathing, a clean rear end.

Social needs: why it cannot live alone

Guinea pigs are a herd species in South America, and according to the RSPCA they become lonely if kept alone. Two females, or a neutered male with a female, are usually the most compatible pairings. Do not keep an unneutered male and female together; uncontrolled breeding will follow.

Cage and living space

Most guinea pig cages sold in pet shops are too small for two animals.

• Floor area: at least 0.7 m² for two guinea pigs (for example 120x60 cm); bigger is always better.
• Flooring: flat flooring; do not use wire-mesh flooring, which offers even less cushioning to a short coat.
• Bedding: paper-based bedding, a fleece cage liner, or dust-free aspen shavings. Do not use pine or cedar shavings, which damage the respiratory tract.
• Hideouts: at least one per guinea pig, plus a spare.
• Position: a quiet spot out of direct sun, away from draughts, at a steady 17-24 °C. Above 26 °C is dangerous.
• Free-roaming time: at least one hour a day in a safe, enclosed area.

Spot-clean daily; change the bedding once or twice a week. Because the coat is short, wet bedding reaches a Rex's skin directly too — do not let cleaning slip.

Feeding: the vitamin C rule

Like humans and other primates, a guinea pig cannot make its own vitamin C.

• Hay (80%, unlimited): timothy or meadow hay should always be available; it is the foundation of digestion and dental health.
• Pellets (one to two tablespoons a day): a guinea pig-specific pellet fortified with vitamin C. Avoid colourful, seed-and-nut mixes.
• Fresh vegetables (a handful a day): sweet pepper, rocket, parsley, purslane, lettuce leaves, cucumber.
• Vitamin C: roughly 10-50 mg a day, which fresh vegetables can supply. Vitamin C drops in water are not recommended; they degrade in light.
• Water: a drip bottle and/or a shallow bowl, changed daily.

Do not give: iceberg lettuce heart, potato, onion, garlic, avocado, chocolate, dairy products, seed-and-nut mixes.

Health and lifespan

Sources generally give a Rex guinea pig lifespan of 5 to 8 years.

Signs that mean a vet visit:

• Not eating, or a drop in the number of droppings (urgent)
• Wheezing, nasal discharge, watery eyes
• Weight loss, inactivity, hiding
• Hair loss, itching, crusting
• Limping, redness or sores on the foot pads

Common health problems:

• Scurvy (vitamin C deficiency): lethargy, limping, joint swelling, bleeding gums. Fully preventable.
• Skin parasites and fungal infection: redness and crusting are easier to spot under a short coat, which is an advantage — but call a vet promptly once noticed.
• Nail problems: nails grow faster in the Rex than in other breeds; neglect leads to toe joint deformity and difficulty walking. Weekly checks are recommended.
• Respiratory infections: common and fast-progressing; wheezing and nasal discharge need urgent veterinary attention.
• Dental problems: insufficient hay lets the back teeth form spurs; drooling and difficulty eating are signs.
• Bumblefoot (pododermatitis): foot-pad sores from wet or hard flooring.
• Heatstroke: above 26 °C is dangerous.

Coat care and handling

1. A weekly check is enough. The short coat does not tangle or mat, so the daily brushing long-haired breeds require does not apply here. Still, go over it with a soft brush once a week and check the skin.
2. Nail trimming: check weekly, trim as needed — this is the grooming item that should not be skipped in this breed.
3. Bathe only when needed: use a mild guinea pig-safe shampoo; frequent bathing dries out the skin.
4. Hold with two hands: one under the chest, the other supporting the hindquarters. Guinea pigs are prey animals — do not grab from above.
5. Keep sessions short and use a towel on your lap.

Enrichment

1. A large floor area is the single most effective form of enrichment.
2. Tunnels and hideouts.
3. Foraging: hide vegetables in the hay.
4. Daily free-roaming time in a safe, cable-free area.
5. A companion: no toy replaces another guinea pig.

History and life in the wild

The guinea pig (Cavia porcellus) comes from the grasslands of the Andes, where it was domesticated thousands of years ago. The Rex coat comes from a natural gene mutation that removes the guard hair and shortens the coat; similar "rex" mutations have arisen independently in other species, including rabbits and mice. In guinea pigs this mutation was selectively fixed and recognised as a distinct breed. Temperament and basic care needs are the same as in other guinea pig breeds — the only difference is coat structure and the grooming routine that follows from it.