Coat types

Body types


Cream Agouti

Genetics: Agouti plus marten (either double marten or marten plus albino) plus the black eye gene plus two copies of the recessive cream/golden gene.

NFRS Standard: To be a mix of mid grey ticking over a mid cream ground, with no suggestion no suggestion of blue or brown tones. Ticking to be darkest along the back and fade down the sides to the pale cream belly. Fur on the face to be lighter on the whisker bed and around the eyes. Eyes black.
Faults: Rusty patches, white toes, darker points on the nose, tail root and feet.


Merle rats seemed to disappear in the UK at one point, but imports in 2015/16 brought merle back to the UK fancy. Merle works on the mink gene, and causes uneven distribution of pigments in the coat, causing distinct spots in the coat. This can appear similar to the ‘patchy moults’ which are commonly associated with mink rats, however these are permanent, and do not change with moults.

Genetics: Currently unclear, but requires mink for expression.

NFRS Standard: Merle rats may be shown in pearl and cinnamon pearl. The unique feature is a pattern of dark splash-spots distributed evenly throughout the entire lighter background colour so as to resemble a merle dog. The markings should be numerous and distinct. Eye colour black.
Genetics: Pearl or cinnamon pearl rats with patchy expression of the pearl gene.

Havana Agouti

Havana agouti is currently a colour shown in New Varieties. There was some debate as to whether or not a standard should be accepted for this colour, as commonly these rats look very similar to a cinnamon. However, with some careful selection, they can be made to look distinctly different.

Genetics: Agouti and mink with one copy of the red eye dilute gene (aammRr). Although red eye dilute is technically a recessive, in certain circumstances it will affect colour even when only one copy is present – and on a mink background is one of those times. Alternatively, aaamam (American mink) from certain lines.

NFRS Standard: To be a light sandy brown caused by the intermingling of light brown ticking over a light fawn ground. Belly to be pale silver, undercoat light brown grey. Foot colour to match top. Eye Colour mid to light ruby.
Serious faults: Dark eye colour. Colour must not conform to the std for cinnamon.

Russian Buff

Russian Buff has only recently been accepted for a standard, whereas Russian Topaz (it’s agouti counterpart) has been standardised for much longer. This is because a lot of selection is required in order to get a Russian Buff to look visually distinct from a standard Buff. At this time there are not thought to be any breeders specifically working on Russian Buff, but they come up in Russian Topaz litters.

Genetics – this is a self rat, with two copies of the Red Eye Dilute gene and 2 copies of the Russian Blue gene.

NFRS Variety Standard: To be a pale greyish beige. Faint light speckling or a subtle ticked effect (heathering) is usual for this variety and is not a fault. Colour to be level throughout. Not to be confused with standard Buff or Platinum. Belly colour to match top, undercolour light greyish beige to the skin. Coat to be short and thick – a long coat or a coat similar to that on other varieties (excluding rex) to be a serious fault. Eyes dark ruby to black.
Faults: Dark, dull or too warm top colour. Light ruby eyes.
Severe Faults: Very pale or dark patches or prominent white eye circles.
Genetics: a/a r/r rb/rb*

Variegated Downunder

This is the third Downunder ‘family’ phenotype to be standardised in the UK. Variegated Downunders are currently shown in the ‘New Varieties’ section at shows. There are still very few breeders in the UK who breed for any of the Downunder types, and currently there doesn’t appear to be anyone breeding specifically for Variegated Downunder. However, they can often appear in Spotted litters.

Genetics: A combination of alleles at the H locus (as per Variegated), plus the Downunder modifier. There is no agreed symbol for this modifier, however it is dominant and not found on the H locus.

NFRS Variety Standard: The head and shoulders to be of a distinct colour with a white spot or blaze on the forehead. Where a spot is present this should be centrally placed on the forehead, round or oval in shape and no bigger than the rat’s eye. Blazes are a wedge shaped symmetrical blaze of white, starting at the nose and taper to a fine point midway between the eyes and ears. Markings not to extend onto the cheeks or the eyes. The rest of the upper portion (back, sides and tail) of the rat’s body to be white, evenly marked with patches and flecks of distinct colour, the colour to conform to a recognised colour variety. Underside should havea broken marked centre line down the belly. Side spots desirable.
Faults: rusty patches, white toes, darker points on nose, tail root and feet


Although not recognised as a variety in its own right for showing in the UK, masked is used as a term for a fairly common mismark that can be seen in litters when breeding for Black Eyed White or Capped rats.

Genetics: As for Capped (homozygous for notched or extreme Hooded locus – hnhn, hehe – presumably hehn), but selected for more white markings.

AFRMA standard: Masked rats may be shown in any recognized color. The body is to be a pure, clean white, free from spots or brindling. A colored mask to cover the face, to include just around the eyes and above the nose, not to extend down the sides of the face onto the jowls or under the chin.

American Irish

The standard for Irish rats in some US clubs probably most closely resembles the UK Berkshire variety, though it is more accepting of rats with less white on their underside. The lesser marked versions are often given the affectionate but descriptive nickname “belly Irish” or “tummy Irish” in the UK – it is not a variety specifically bred for over here though, just something that occasionally turns up.

Genetics: Most likely as for Berkshire. Rats carrying one copy of the roan gene can also appear to be a type of American Irish , depending on other modifiers (Roro).

AFRMA standard: Irish rats may be shown in any recognized color. The top color is to be judged as to the respective color. Distinctive markings are the white underside, with four white feet and a white tail tip. The under marking should be a pure clean white, of moderate size and as even in shape as possible, not extending onto the legs, sides, or chest. The white feet should resemble the stops on a Dutch rabbit. The tail should be colored for most of its length, with a white tip of no more than one-fourth of its total length.

English Irish

AKA Irish

Russian Dove

AKA dove

Russian Pearl

The Pearl gene can be confusing genetically, since it only has an effect on Mink based rats (and even then, it’s not as predictable as you’d hope it would be). Therefore, the Russian pearl variety is also described as Dove Pearl or Russian Cinnamon Pearl, since it is a combination of Russian blue, Pearl, and a Mink gene too.

Genetics: Russian blue combined with Pearl and either Mink or American Mink (aammrbrbPepe or aaamamrbrbPepe)

NFRS standard: To be a mid silver, with a creamish undercolour. The majority of hairs to be pearl tipped with grey, interspersed with occasional grey hairs. The top coat must be short and thick with a slight metallic sheen. Belly fur to be a pale creamy grey. Foot colour pale grey. Eyes black.