Double Rex

Description and History of the Double Rex Rat

Introduction

The domesticated rat (Rattus norvegicus) is a species that has fascinated pet owners, breeders, and scientists for centuries. Through generations of selective breeding, a remarkable variety of colors, patterns, and coat types have emerged, each with its own unique appeal. Among the most distinctive and visually intriguing of these is the Double Rex rat. Known for its patchy, curly, and often nearly hairless appearance, the Double Rex rat stands out in the world of fancy rats. This article explores the physical characteristics, genetics, origins, and cultural significance of the Double Rex rat, providing a thorough overview for both seasoned breeders and those new to the world of fancy rats.

Physical Description

The Double Rex rat is instantly recognizable due to its unusual coat, which is characterized by patchy hair growth, curly fur, and areas of baldness. Unlike standard rats, which have smooth, even coats, Double Rex rats have a unique appearance that can vary greatly from one individual to another.

Key Physical Traits:

Coat Texture: The fur of a Double Rex rat is curly or wavy, similar to that of a standard Rex rat, but with significant differences. Double Rex rats have two copies of the Rex gene, which results in a much more pronounced effect on the coat.
Patchiness: One of the most distinctive features of the Double Rex rat is its patchy coat. These rats often have areas of baldness interspersed with patches of curly or wavy fur. The pattern and extent of baldness can change over time, with some Double Rex rats becoming almost completely hairless as they age, while others retain some patches of fur throughout their lives.
Whiskers: Like Rex rats, Double Rex rats have curly, crinkled, or corkscrewed whiskers. These whiskers are often shorter and more fragile than those of standard rats.
Skin: The exposed skin of Double Rex rats is soft and warm to the touch. The skin may be pink, gray, or pigmented, depending on the rat’s underlying color genetics.
Color and Pattern: The Double Rex gene affects only the texture and presence of fur, not the color or pattern. Double Rex rats can be found in every color and pattern available in fancy rats, including agouti, black, mink, blue, and more.
Body Type: Double Rex rats are otherwise identical to standard rats in size, shape, and proportions. Adult Double Rex rats typically weigh between 250 and 500 grams, with males being larger than females.

The appearance of a Double Rex rat can change dramatically over its lifetime. Many Double Rex rats are born with a full coat of curly fur, which begins to fall out in patches as they grow. The extent and pattern of baldness can fluctuate, with some rats regrowing fur in certain areas and losing it in others.

Genetics of the Double Rex Rat

The Double Rex trait is the result of a specific genetic combination involving the Rex gene. The Rex gene, often abbreviated as “re,” is a simple recessive gene that causes curly fur and whiskers when present in two copies. However, when a rat inherits two different curly coat genes—one from each parent—the result is a Double Rex.

How the Double Rex Gene Works:

The Double Rex rat is produced when a rat inherits two copies of the Rex gene (re/re), or one Rex gene and one Hairless gene (re/hr or hr/hr). The interaction between these genes disrupts normal hair growth, resulting in the patchy, nearly hairless appearance characteristic of Double Rex rats.
The Double Rex gene combination affects the structure of the hair follicles, leading to weak, brittle hair that falls out easily and does not grow back evenly.
The Double Rex gene does not affect the rat’s health, temperament, or any other physical trait, aside from the coat and whiskers.

Inheritance Pattern:

Two Double Rex parents: All offspring will be Double Rex or Hairless, depending on the specific gene combination.
One Double Rex parent, one Rex parent: Approximately half the offspring will be Double Rex, half will be Rex.
One Double Rex parent, one standard: All offspring will be Rex carriers, none will be Double Rex.
Two Rex parents: About 25% Double Rex, 50% Rex, 25% standard.

Because the Double Rex gene is a combination of two recessive genes, careful breeding is required to produce Double Rex offspring. Breeders must keep track of which rats carry the Rex and Hairless genes and plan pairings accordingly.

Origins and Discovery

The Double Rex rat is a relatively recent addition to the world of fancy rats. The mutation is believed to have arisen spontaneously in domesticated rat populations, as is often the case with new coat types.

Early Reports:

The first documented Double Rex rats appeared in the United States in the late 20th century, likely in the 1980s or early 1990s.
Breeders noticed the unusual patchy, curly coats in certain litters and began selectively breeding these rats to stabilize and propagate the trait.

Development and Spread:

Once the Double Rex trait was recognized, breeders worked to establish stable lines and to introduce the gene into various color and pattern combinations.
The Double Rex rat quickly gained popularity among fancy rat enthusiasts, both for its unique appearance and for the challenge of breeding and exhibiting a new variety.
The variety spread from the United States to Europe and other parts of the world, where it was embraced by breeders and pet owners alike.

Recognition:

The Double Rex rat is now recognized by many rat fancier organizations, including the American Fancy Rat and Mouse Association (AFRMA) and the National Fancy Rat Society (NFRS) in the UK.
Breed standards have been established to define the ideal Double Rex coat, emphasizing patchiness, curly texture, and overall health.

Spread and Popularity

The Double Rex rat’s rise in popularity was swift, driven by its unique appearance and the enthusiasm of breeders. The combination of a patchy, curly coat and the ability to combine the Double Rex gene with any color or pattern made it a favorite among both experienced breeders and newcomers.

Reasons for Popularity:

Aesthetic Appeal: The patchy, nearly hairless coat of the Double Rex rat is visually striking and sets it apart from other varieties.
Variety: Because the Double Rex gene can be combined with any color, pattern, or ear type, there is a tremendous diversity of Double Rex rats available.
Show Success: Double Rex rats are popular in rat shows and competitions, where their unique appearance often draws attention and admiration.

Double Rex rats are now widely available from breeders, pet stores, and rescue organizations. They are often recommended as pets for those who appreciate their beauty and enjoy the challenge of breeding and exhibiting fancy rats.

Cultural Impact and Significance

The Double Rex rat has had a significant impact on the fancy rat community and the broader world of pet keeping. Its introduction marked a new era in rat breeding, demonstrating the potential for selective breeding to produce novel and desirable traits.

Influence on Breeding:

The Double Rex mutation inspired breeders to experiment with new combinations, leading to the development of Double Rex rats in every conceivable color and pattern.
The popularity of Double Rex rats has encouraged responsible breeding practices, with an emphasis on health, temperament, and genetic diversity.

Influence on Public Perception:

The Double Rex rat’s “quirky” and “unusual” appearance has helped to change public perceptions of rats, which are often viewed negatively due to their association with pests and disease.
Photos and videos of Double Rex rats are popular on social media, where their patchy coats and playful antics have won over countless fans.
The Double Rex rat has become something of an ambassador for the species, helping to promote rats as intelligent, affectionate, and rewarding pets.

Representation in Media:

While not as prominent as some other animals, Double Rex rats have appeared in books, articles, and online content about pet rats.
Their unique appearance makes them a favorite subject for artists and photographers.

Care and Considerations

Caring for a Double Rex rat is similar to caring for any other fancy rat, but there are some special considerations due to their unique coat.

Key Care Points:

Housing: Double Rex rats are active and intelligent, requiring plenty of space to explore and play. Multi-level cages with tunnels, hammocks, and toys are ideal.
Diet: A balanced diet of high-quality rat pellets, supplemented with fresh fruits, vegetables, and occasional treats, is essential for health.
Social Needs: Rats are highly social animals and should be kept in pairs or groups. Double Rex rats are no exception and thrive with companionship.
Health: The Double Rex gene does not predispose rats to any specific health problems, but their exposed skin can be more sensitive to injury, dryness, or irritation.
Grooming: Double Rex rats groom themselves and each other, but regular handling helps to keep them tame and well-socialized.

Special Considerations:

The exposed skin of Double Rex rats is more vulnerable to scratches, sunburn, and temperature extremes. Owners should provide soft bedding, avoid rough cage accessories, and keep the cage out of direct sunlight.
Double Rex rats may be more prone to dry skin. Providing a humid environment and avoiding harsh soaps or chemicals can help maintain skin health.
The curly whiskers of Double Rex rats may be more fragile and prone to breakage, but this does not affect the rat’s health or well-being.

Breeding and Ethical Considerations

The popularity of Double Rex rats has led to increased interest in breeding, both among hobbyists and commercial breeders. Responsible breeding practices are essential to ensure the health and well-being of Double Rex rats.

Best Practices:

Genetic Diversity: Breeders should avoid inbreeding and strive to maintain a diverse gene pool.
Health Screening: Breeding rats should be healthy, free of genetic disorders, and have good temperaments.
Education: Prospective breeders should educate themselves about rat genetics, care, and ethical breeding practices.

Rescue and Adoption:

As with all popular pet varieties, there are Double Rex rats in need of homes. Adoption from reputable rescues is encouraged for those who do not wish to breed.

Conclusion

The Double Rex rat is a testament to the power of selective breeding and the enduring appeal of domesticated rats. With its patchy, curly coat and friendly temperament, the Double Rex rat has captured the hearts of pet owners and breeders around the world. Since its discovery in the late 20th century, the Double Rex rat has become one of the most popular and recognizable varieties of fancy rats, celebrated for its unique appearance, adaptability, and charm.

The Double Rex rat’s story is one of innovation, community, and the joy of discovery. Its introduction has enriched the world of fancy rats, inspiring breeders to explore new possibilities and helping to change public perceptions of these remarkable animals. Whether as a show animal, a beloved pet, or a symbol of the diversity of domesticated rats, the Double Rex rat stands as a shining example of what can be achieved through careful breeding, responsible care, and a passion for animals.