Fancy rat

The fancy rat or pet rat is a domesticated breed of the brown rat (Rattus norvegicus). The name "fancy rat" has nothing to do with the "fanciness" of their appearance but derives from the meaning of "to fancy". Thus, one who keeps pet rats is said to be involved in "rat fancy." There are some rat fanciers who domesticate black rats (Rattus Rattus), and Gambian pouched rats (Cricetomys gambianus), but these are not generally referred to as fancy rats as the hobby does not formally center around them.

Specially bred as pets at least since the late 19th century, the rats are sociable, intelligent animals and can be trained to use a litter box, come when called, and perform a variety of tricks. Pet rats behave differently from their wild relatives depending on how many generations they have been removed, and, when acquired from reliable sources, they do not pose any more health risk than other, more common pets.

Pet rats live about 2 to 3.5 years, although the oldest rat on record, a lab rat called Rodney, reached a purported age of 7 years and 4 months, according to the 1995 Guinness Book of Records. Bucks (male rats) reach an average weight of to , while does (female rats) range from to . Female rats tend to be more active than male rats.


The origin of the modern fancy rat is probably the rat-catchers of the late 19th century who trapped rats and were paid by town governments per rat, and who also kept certain rats for exhibition/gambling fights. They began breeding rats and became attached to some as they discovered how intelligent and trainable rats could be. One of the most famous of these rat catchers was Jack Black, ratcatcher to Queen Victoria, who became known for breeding and selling pet rats around 1840-1860.

Rats became more and more domesticated and people enjoyed them as easily bred, social, and intelligent pets. The first rat show was held in 1901 in England. Beatrix Potter, author of the "Peter Rabbit" series of children's books, had a white pet rat of which she was very fond, and in remembrance of which she dedicated the story "The Roly-Poly Pudding".

Rat fancy as a formal, organized hobby began when Mary Douglas asked for permission to bring her pet rats to an exhibition of the National Mouse Club at the Aylesbury Town Show on October 24, 1901. Her black and white hooded Rattus norvegicus won "Best in Show," and the Rat Fancy was formally launched.

The original Rat Fancy lasted until 1931, as part of the National Mouse and Rat Club. The modern Rat Fancy was revived in 1976 with the formation of the National Fancy Rat Society, and the fancy spread around the world.

Ratkeeping grew in popularity in the 1970s, leading to the formation of the British National Fancy Rat Society in 1976. There presently exist several rat fancy groups worldwide and pet rats are commonly sold in stores and by breeders.


As in other pet species, a variety of colours, coat types, and other features that do not appear in the wild have been either developed or arisen spontaneously in rats.


While some pet rats retain the "agouti" (three tones on the same hair) colouring of the wild brown rat, others may be black based colours (a single color on each hair). Agouti based colours include: agouti, fawn, cinnamon, blue agouti, and amber. Black based colours include blue, chocolate, silver, black, white, pearl, and mink.

Colour definitions tend to vary for more vague varieties, like fawn for champagne or mink for cinnamon. They can fluctuate between and even within different countries or clubs.

There are three different types of eye colors that rats can have: black, pink, and ruby. Pink and ruby eyes are controlled by a gene that dilutes the normal black color of the eyes, but it also affects the coat. Ruby eyed rats have eyes that normally appear black, yet appear red while in the light.


In addition to the many colours, there are also many different markings. Pet rats can appear in any combination of colour and marking. The markings are typically in reference to the patterns and ratios of coloured hair versus white hair. The two extremes would be a self (completely solid, non-white colour) and a Himalayan (completely white with a gradual blend of colouring towards its nose).

Markings usually have a strict standard. For example, in the case of hooded rats, the stripe or "saddle" should be a single, unbroken line running down the spine and possibly partly down the tail. However, many rats are not bred strictly to the standard, such as those found in pet shops, and will have "mismarkings."

Internationally recognized standards include:

  • Berkshire - coloured top, white belly
  • Hooded - colour running from full head down spine
  • Capped - colour on full head only
  • Variegated - a blaze, or short white strip on the forehead, with a fully coloured head and splotches or flecks of colour running down the back only
  • Essex - similar to Berkshire, only that the colour fades to white rather than ending abruptly
  • Bareback - colour fully on head, neck, and chest only (not officially standardized in the UK)
  • Irish or English Irish - In the UK this marking is only standardized as an equilateral triangle of white with a side beginning at the chest, or between the front legs, and the point ending mid length. The AFRMA, another international rat fancier club, distinguishes this marking as the English Irish and allows for another standard Irish in which the rat may have white of an even or symmetrical nature anywhere along its underside.

Other marking varieties include Dalmatian-like spotting, blazes, masks (only around the eyes), Siamese (typically a gradient of colour on the nose), and "downunders" (an Australian variety which have a solid colour stripe on the belly or a colour marking that correspond to those on top.). Additionally, eye-colour is considered a subset of colouring, many coat-colour definitions including standards for the eyes. They may be black, pink, ruby, or odd-eyed (one of each).

Coat types

There is a relatively small variety of coats, and not all are internationally standardized as such. The most common type is the Normal or "Standard," which is allowed variance in coarseness between sexes; the males have a coarse, thick, rough coat, while the females' coats are softer and finer.

Well-known coats include: Rex, in which all the hairs are curly, even the whiskers; Velveteen, a softer variation on the Rex; Satin or silky coats which are extra soft, fine, and have a sheen; Harley, characterized by long straight hairs. Remaining coat types are not defined by the hair itself, but rather by the lack of it.

Hairless rats

Hairless, or Sphynx rats are a coat variety characterized by their completely bare skin except perhaps near the top of their heads (not standard) and their whiskers. Semi-hairless rats, sometimes called double-rex rats, have varying areas of bare skin or very short fur on their bodies. Because the Rex coat is a dominant gene it only needs one allele to affect the rats appearance. However, when two copies of the gene appear, by breeding two Rexes together, the coat is affected differently. One subset of semi-hairless rats, patchwork rats, constantly lose hair and regrow it in different "patches" several times throughout their lifetimes. Semi-hairless varieties are produced by different combinations of the various genes that cause Rex, or curly, coats.

Hairlessness in laboratory rats
In laboratory rats there are currently three known genes that can cause recessive hairlessness. They are denoted as rnu (Rowett nude), fz (fuzzy), and shn (shorn). When an organism is identified as having a visible recessive trait, the gene pair (from the father and mother) is listed like such: rnu/rnu. All three gene types have characteristic health problems. The hairless rats kept as pets do not seem to be related to the hairless lab rats and do not have any unusual health problems.

Rowett nudes, first identified in 1953 in Scotland, have no thymus. The lack of this organ severely compromises their immune system, infections of the respiratory tract and eye increasing the most dramatically. Their average life span is about nine months. Fuzzy rats were identified in 1976 in a Pennsylvanian lab. They are prone to malocclusion, or tooth misalignment - and about half of all males and 75% of all females require their teeth to be regularly trimmed to maintain normal function. However, the leading cause of death among fz/fz rats is ultimately a progressive kidney failure that begins around the age of one. Even in germ-free conditions, all males and 80% of females will die from kidney failure. Their average lifespan is 17 months for males and 20 months for females.

Shorn rats, identified in 1998 in Connecticut also suffer from severe kidney problems. All rats with this genotype die of severe kidney abnormalities by 14 months of age. Their average lifespan is only around 10 months.

All three types (rnu/rnu, fz/fz, and shn/shn) have curly whiskers and may potentially be identified as Patchwork rats. Despite their health problems and difficulties with weaning, they are all still fertile and have normal sized litters.

Physical changes

Two of the most prominent (and thus standardized) physical changes applied to rats through selective breeding are the development of the Manx and Dumbo. The Dumbo, whose origins are in the United States, is characterized by having large, low, round ears on the sides of its head. Manx rats borrow their name from the tailless cats on the Isle of Man. Manx rat tails also come in the same stumpy, rumpy, and rumpy-riser varieties as those of Manx cats.

Ethics of selective breeding

There is controversy amongst rat fanciers as to whether or not breeding hairless and tailless rats is ethical. The tail is vital for rats' balance and for adjusting body temperature. Tailless rats have greater risk of heat exhaustion, poor bowel and bladder control, falling from heights, and can be at risk for life-threatening deformities in the pelvic region like hind leg paralysis and megacolon. Similarly, hairless rats are missing their warmth-preserving coat, are more likely to be adversely affected by the cold, and have lowered immune systems.

The issue of culling has also caused some controversy. In the rat breeding community this has led to the move away from the breeding of "marked varieties" and concentration on "self" coloured varieties.


Because R. norvegicus and related species are seen as pests, their intentional import into foreign countries is often regulated. For example, in Australia, the importation of foreign rodents is prohibited and so various coat types, colours, and varieties have had to been bred seperately from foreign lines, or are just not obtainable within that country.



Fancy rats being defined as a purely domesticated subset of either R. rattus or, more typically, R. norvegicus, are more prone to specific health concerns and diseases than their wild counterparts. Conversely they are also far less likely to succumb to certain illnesses that are prevalent in the wild. The major considerations for susceptibility include exposure, living conditions, and diet.

Rats that live their entire lives indoors are able to avoid disease-causing bacteria such as Salmonella and Pseudomonas aeruginosa, the latter being absent in treated water. They may also more easily avoid vectors like cockroaches, beetles, and fleas who are essential for the spread of Bubonic plague and intestinal cestodes like the Rat tapeworm.

Additionally, pet or laboratory rats enjoy the natural benefits of having a consistent and well-balanced diet. However, this could be countered with the fact that outside of the laboratory, rats may not always be receiving proper nutrition. Finally, rats that are in the care of humans have access to surgery for the benign mammary tumors that are common to both sexes.

While living indoors decreases the risk of contracting certain diseases, living in close quarters with other rats, being unable to always seek proper protection from environmental factors (e.g. temperature, humidity, drafts), being fed an unhealthy diet, and the stresses naturally associated with living in an unnatural habitat can all have adverse effects on a rat's health making them prone to specific conditions.

Specifically, Tyzzer's disease, Protozoic infections (e.g. Giardia muris), and Pseudotuberculosis are usually seen in stressed or young rats. Additionally, pet rats are exposed to Streptococcus pneumoniae, a zoonotic disease caught from humans. Another bacteria associated with humans, Pneumocystis carinii, is actually found in almost all domesticated animals. However it is asymptomatic unless the rat's immune system is compromised by illness, then it can develop into pneumonia.

Several diseases, like Rat Coronavirus Infection (RCI), Sendai virus, and Murine Respiratory Mycoplasmosis (MRM, Mycoplasma pulmonis), are more prevalent simply because their highly contagious natures work in tandem with the way rats are kept in laboratories, pet stores, and by breeders. It should be noted, however, that MRM is far less likely to occur in laboratory rats than those kept as pets.

Pet rats can also develop pituitary tumors if they are given high-calorie diets, and ringtail if they are placed in areas with low humidity, high temperatures, or drafts. Staphylococcus spp are a mostly benign group of bacteria that commonly reside on the top of the skin, but cuts and scratches can open up the pathways for them to cause ulcerative dermatitis. Cuts and scratches are a normal part of every rat's life; they are social animals who periodically spar for positions within their loose hierarchy. In cages, however, stressors can increase aggressiveness between rats, causing more frequent and intense fighting.

Domestic rats in entertainment media

Since Muybridge's first films, rats have been widely used in entertainment media. Due to their intelligent nature and trainability, rats have appeared in over 413 major film releases throughout the world, and in at least seventy-one television series. For example, a pet rat named Scabbers is a character in the Harry Potter novel/film series.

Rats in films are often depicted as squeaking, usually for dramatic effect. However rats do not usually squeak, normal vocalizations being too high-pitched for human ears; they may do so only if distressed, hurt, or annoyed.

Rats are often in roles that emphasize the popular perception of them as malevolent vermin. The 1971 film Willard is a notable example; it features a horde of rats trained to exact revenge on behalf of a social misfit, but also shows some realistic social interactions among the rats. An alpha rat named Big Ben (played by a giant pouch rat) becomes jealous of the attention a smart rat named Socrates is getting, and tries to murder his rival.

Pet rats are featured in many films, such a Roddy St. James in Flushed Away and Beany in The Abyss. In The Secret of NIMH, genetically enhanced lab rats are portrayed as nearly human. In 2007, Disney/Pixar released one of the few movies to actually feature a rat as the main character. Ratatouille stars a rat named Remy who wants to be a Parisian chef. According to the DVD and Blu-Ray releases short film Your Friend the Rat, Remy and his brother, Emile, are both brown rats. In the 1997 animated movie The Ugly Duckling features a female rat called Scruffy as one of the main characters.

In the Buffy the Vampire Slayer television series, the character of Amy is turned into a rat and is kept as a pet by Willow for several seasons before she is changed back into a human. Pet rats are also featured in House and Fawlty Towers. Even computer games involve fancy rats. Phantasmagoria 2: A Puzzle of Flesh features a main character who has a beloved pet rat named Blob and rats can be kept as non-combat pets in World of Warcraft. Comix Zone's main character has a pet rat sidekick, RoadKill. In the novel "Stargirl" Stargirl has a pet rat named Cinnamon.


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