Rex Guinea Pig Breed Guide: The King of All Cavies?

This breed isn't called "Rex" - meaning "King" - for nothing, and these cavies are among the largest of all Guinea pigs.

Published April 19, 2023
Cute Rex Guinea pig.

Rex Guinea pigs are one of the most popular cavy breeds, with their wiry coats and large size. Their friendly demeanor and fluffy, potato-like appearance make them highly desirable. Like most breeds, they are easy to take care of, and make great pets for kids and adults alike.

History and Origin

Guinea pigs were originally bred by the Incas and have been domesticated for about 5,000 years. The exact origin of the Rex is not entirely clear, though this unique breed has been around for some time. The British Cavy Council recognizes the breed, but the American Cavy Breeders Association (ACBA) does not - However, the ACBA does recognize the Teddy, a similar breed.

Fast Fact

The word "Rex" comes from Latin, and translates to "King" or "Ruler." This is a suitable name for the breed, because they are so much larger than other Guinea pig breeds.

Teddy Versus Rex Guinea Pigs

Rex Guinea pigs are often confused with teddy Guinea pigs. Each of these breeds has a genetic mutation that involves their coat, making it wiry or bristly. However, the Teddy Guinea pig is softer than the Rex. The Rex's coat is more coarse. The Teddy Guinea pig also has forward-growing hair above their eyes, differentiating them from the Rex.

Teddy Guinea pig standing on carpeting.

Appearance and Physical Traits

Unlike other Guinea pigs, which have straight fur, the Rex has a short, dense, and curly coat that is soft to the touch. Their coat is about a half inch in length. They're also known for their large, droopy ears.

Size and Weight

The Rex Guinea pig is larger than almost all other adult Guinea pig sizes. They can grow up to 18 inches in length, and are often between 1 to 3 pounds.

Enclosure Size Requirements

Despite their unique appearance, Rex Guinea pigs require similar care to other breeds. They need a clean and comfortable living space that is at least 4-square feet, with plenty of room to move around and play. If you can swing it, a larger enclosure is better. Also, keep in mind that all Guinea pigs need at least one hour outside their enclosures every day, for exercise and enrichment.

Coat Colors

The rex Guinea pig can be found in several coat colors, including:

  • Gold
  • Red
  • Cream
  • White
  • Chocolate

They can also have a mixture of these coat colors outlined above.

Unique Traits

The following are traits unique to the Rex:

  • Rex Guinea pigs lack guard hairs, which makes them ideal for people who love Guinea pigs, but need a breed that is known to be hypoallergenic.
  • Their toenails grow more quickly than other breeds, requiring them to be trimmed on a more frequent basis.
  • The Rex's fur curls inwards towards its body instead of outwards like that of other varieties.

Average Lifespan

Rex Guinea pigs live 5 to 8 years in captivity. However, with consistent care and attention to their needs - including their diet and enrichment requirements - it is common to see Rex Guinea pigs reach 10 years of age or more.

Care Basics

Despite their unique appearance, Rex Guinea pigs require similar care to other breeds. Like all other Guinea pigs, the Rex requires a continuous supply of Timothy hay or another high-quality hay, a nutritious pellet diet, fruits, and veggies.

Rex Guinea pig on blue background.


The Rex Guinea pig requires regular exercise. Becuase they are a larger breed, without enough physical activity they can become overweight a little more quickly than other cavies (at least, in some cases). While their cage should be large enough to run around in, they still need consistent time outside their enclosure every day. Hiding places in their enclosure can also provide Guinea pigs with some fun playtime.

Quick Tip

You should never place a running wheel in any Guinea pig's cage, as they could injure their back playing on it.


The Rex Guinea pig's wiry fur coat requires more maintenance than other Guinea pigs. They should be brushed on a daily basis to prevent matting or tangling. Remember to brush gently, even if your Guinea's fur has tangles. You can easily hurt them if you pull too harshly. However, if done properly, this breed often enjoys having their fur brushed.

Short-coated Guinea pigs, like the Rex, do not need baths very often, though some bathing is beneficial to prevent feces from building up on their fur. Most don't need full baths, but be certain to provide this breed with a thorough cleaning using cavy-friendly shampoo.

Diet and Feeding

Other than the fact Rexes are larger than most cavies, their nutritional requirements are very similar. They need a varied diet that includes appropriate types of hay, a commercial pelleted diet made for Guinea pigs, and a mix of vegetables and fruits for stimulation and to make sure their general nutrition needs are met.

Behavior and Handling

Although each Guinea pig, regardless of breed, has their own personality, the Rex is known to be friendly, affectionate, and calm. Rex Guinea pigs do best when they're kept in pairs. They can be kept with other Guinea pig breeds. They just want some company.


Like other Guinea pigs, the Rex is prone to certain ailments:

  • Heatstroke: This Guinea pig can do better with colder temperatures than hot. If the temperature goes over 75 degrees, they are prone to heatstroke.
  • Flystrike: This is when flies burrow their eggs into your Guinea pig's skin.
  • Respiratory infections: If you notice your Guinea pig sneezing or producing mucus coming from their nose, contact your veterinarian immediately, as this infection can worsen quickly.
  • Bumblefoot: If your Guinea has bumblefoot, you will notice irritation on their feet that leads to an infection.
  • Ingrown toenails: Since this breed's toenails grow so quickly, they are more prone to developing ingrown toenails than other breeds, especially if they aren't groomed properly.

Caring for Babies

Rex Guinea pig babies need milk from their mother for the first several weeks of their lives. However, they will begin eating solid foods after only a few days. Since their mother only feeds them a few times per day, the mother can appear as if she has abandoned her young, when she is actually still doing her job. Only take babies if absolutely necessary, because they will do best with natural rearing from their mother.

Availability and Cost

If you're searching for a Rex Guinea pig, you may find them at some pet stores, but your best bet is to locate a breeder. Because the breed is not recognized by the ACBA in the U.S., you may need to do a bit of searching to find one. You can expect to pay between $50 and $100 at a pet store, or more from a breeder.

Don't forget about the cost of developing and maintaining their habitat. You will also need to purchase food and hay on a regular basis. And be prepared for any necessary veterinary expenses.

Silver rex Guinea pig, right, with silver English, left.

Are They Good for Children?

The Rex can be a good choice for your child due to their love of being petted, brushed, and spending time with their human families. They love to be held and cuddled, but like other piggies, they can be easily hurt if they are dropped or squeezed. Make sure your child is responsible with handling, and make sure to teach them how to handle Guinea pigs properly prior to adopting them.

Is the Rex Guinea Pig Right for You?

If you're searching for a lovable, fluffy Guinea pig and you're ready to maintain their fast-growing nails, the Rex Guinea pig could be the breed for you. Prior to choosing a breed, do your research to determine which breed is best for you and your family, or your children.

Rex Guinea Pig Breed Guide: The King of All Cavies?