Updated: Oct 30, 2019

The Russian Moons are currently an unknown gene. It was been tested against RED and PED and Moon proved to be neither. Visit the bottom of this page for photos and videos of our Moon Rats.



"Overview: This page is dedicated to the understanding, recording and discussion of the unknown rat genetic puzzle we refer to as 'Russian Moons', or 'Moons'. While our understanding of the variety certainly has improved from more than 7 years of test breedings, the true genetic makeup of what makes the Moons a 'Moon' is yet to be fully determined. I intend this page to be a way for other breeders interested in this variety to have a go to point for information on them as well as a place to talk about theories on the origins and genetics of it as well as a way to keep everyone updated on new findings. I caution that this is not a new variety declaration page (until further evidence supports that claim).

The Physical Descriptions: Phenotypically (the physical outward appearance) typical of this variety is a bluish/beigish shimmery off white coat color, pink to ruby eyes. There does seem to be some variation in the variety depending on what the breeder had selected for and what else is going on within the line. The Moons here at Px seem to have more of the beigish hue and darker red to ruby eyes where as the ones at Bellaratta's Nest (BN) have more of the icer/bluer hue and pinker eyes. Another aspect that seems to be connected, though not necessarily genetically linked, is a difference in the coat itself. The name "moon" originated from the first moon rat the showed up in an Apr 2005 litter named "Bella's Moon" as well as the color looks like that of a shimmery full moon.

Notes on the Emerging Coat Type: An additional note on the moons is the emergence of a very soft fluffy 'plush' coat where the guard hairs are just as soft as the soft downy under coat and slightly reduced. I have seen this new fur type in the russian moons and with the russian blues so it does not seem tied directly with whatever mutation is causing the moons specifically but possibly with the line and even more so possibly a new or re-emergence of a fur mutation type. I currently have 3 females with this fur type and have yet to see it on a male but have heard of one appearing at Heart of Texas (HOT) Rattery. Another note about this fur type is the difficultly of seeing it at early development, typically it emerges at maturity and later (3-5 months) and becomes more pronounced (shorter, more 'plush') as the rat ages. It also does not completely show in all the pups in a litter, usually its only a small few out of several and then randomly between generations. There are no current genetic theories outside of a resurrection of the extinct 'velvet' coat or a strong double coat as of yet on the new fur type but samples of fur have been sent to two independent sources to take a closer look at it under the microscope in late 2012.

Pedigree History: For me, the Moon story began in April 2009 after obtaining two breeding rats from Andover Rattery (ANR) named ANR D'Angelo (RB berk) and ANR Firestorm (Black berk). After doing a daughter back to father breeding, we got a very usual color no one had seen before, it was a bluish/beigish hued shimmery off white color with red eyes. When compared directly to a genetic albino/siamese/himi or beige rat, the color was very distinct from these including their distinct shimmery (not shinny) overtone. At the time, we chalked it up to a russian blue dilute of some sort, either a double, triple or multi dilute and began the process of eliminating these possible other dilutes from the line.

Genetic Theories


Along the way, we have been entertaining several theories as to what is "Moon" from a genetic standpoint. Here are the previous theories up to the newest ones. As we test and work more with the variety, we will better be able to eliminate some and come up with new ones. We encourage the rat community to enter in their own theories so that we can explore all options.

The Multi-Dilute Theory


Initial thoughts were that this is simply a case of multi-dilutes causing a washed out color. Initial color mutations thought involved were Russian blue, American Blue, American Mink, RED (red eye dilute), PED (pink eye dilute). The next mutation we tested early on was the R.E.D. (red eye dilute r) and found that Moon was genetically incompatible with this mutation, producing a litter of all blacks.  The next possibility was the P.E.D. (pink eye dilute p) causing a russian champagne despite the fact that no champagne or any other PED based color had yet to show even after more than 11 inbreedings and line breedings. To be absolutely sure and due to the lack of a pure PED test breeding option we sent off genetic material to the Director of the Rat Resource and Research Center at RADIL and asked if she could test specifically for pink eye dilute in late August of 2012.


The results were quite unexpected: "The sample appears not to be wild type for the pink eye dilute p mutation based on our assay. We tested for the classic p mutation and it was not present. I wonder if it could be a novel mutation in that gene. If you are not in too much of a hurry, I could learn more about the gene and see if it would make sense to do an experiment to examine the entire gene sequence and see if there are any unexpected differences anywhere in the gene." There was never any American mink present in any of the breedings here at Px (until the recent litter from Shaun x Sachiko) and, while present earlier in the breedings at BN, has not shown to be of any impact or involvement on the Moons. American blue has not been in the RB line of BN/Px since its early inception back in 2001 and was lost shortly after and way before the moons showed. It has also never showed in any litters of the moon testing. Hence, from test breedings, genetic genome testing and statistics, we have so far found that only Russian blue dilute seems to be present in almost all of the results in some way, though it was not known whether it has to be involved at all for the color to show or be present. Most likely, the line itself is mostly homozygous for RB and thus the color has been involved with the Moons from its inception on. Recent breeding however seem to indicate that the RB can be removed from the equation and moon is still present. More definitive testing against a for sure non-RB is next.

Single Dilute Mutation Theory


One possibility that has not been ruled out yet is that we are dealing with a dilution mutation that affects the coat and eye color together much the way a simple recessive color/eye dilute does (not as a pigment distributed mutation would). This new mutation would also then be able to be isolated and reproduced on any color, with or without the Russian blue. Tests with an unrelated agouti would help determine what pigment the mutation affects- is it the eumelanins (dark brown to black) or the phaeomlanins (red to yellow) or both. Generally dilution mutations affect both of these melanins in some way along with the eye pigment so if this is a dilute mutation, this disorder of the melanosme formation would be pretty extreme, making it much more extreme than even p (pink eye dilute).

A Form of Albinism


It has been well documented that there are several forms of Albinism in the human population that is also present in vertebrae organisms, each effecting in some degree (compete or partial) the pigment in skin, eyes and hair through absence or defect of Tyrosinase (which aids in the production of melanin). Due to the varying degree that Albinism affects organisms, its possible that we are dealing with a undocumented or new Albino or achromia disorder mutation. Given the extreme amount of pigment loss, this theory pans out better than the rest so far and seems to follow a simple recessive mutation inheritance like the albino c. Further tests would need to see exactly where this mutation may be to help give some insight as to whether it is or not an Albinism (such as is it on the C locus where we find our currently known and mapped albino c already). The dominant black eye gene has been involved with many of the breedings  but as of yet, we have not had a black eyed moon, this could indicate that it is not on the C locus as so far, the black eye gene needs C locus mutations to display. Because this theory has not been singled out yet and tested, the statics do not yet support the inclusion or exclusion either way for that locus and specific testing would be needed in this direction.

Alternative Mutation Theories


Alternative mutation theories include a pigment distribution mutation (like the RB) where the pigment is unevenly distributed in the hair shaft leading to heahtering look, though this is unlikely to be acting solely as such. Instead, a pigment distribution disruption could be in concert with a dilute mutation or it could be that its a dilute mutation that allows for the heathering of the russian blue to show through. This could be why there are differing shades going on and a slightly heathered look to some of the moons. Given the nature of russian blue mutation it is most likely not exactly like it but rather the concept of pigment disruption could be considered in an extreme manner for the moons. Other alternatives is that this is a completely new mutation unlike anything previously seen and the exact mode of mutation could be unique in itself.

The Moon Relation to Russian Blue


I thought I should separate this out into its own segment due to the overwhelming assumption that moon must be tied to RB when this assumption cannot be made at this point in testing or with the evidence thus far. The result of a RB self buck x a moon self doe gives us black offspring tells us that the moon doe must only carry RB and therefore its possible to separate the RB from the Moon. However, more tests need to be done to separate the moon from RB and see if the color is still reproducible on a for sure non-RB. Exactly HOW this effects RB is still up for debate: is it a dilute that's inherited along with RB, is is a situation like albino c and ch where some pigment or heathering characteristic is allowed to show through but only with RB.

Final Words and Thoughts: More information, further tests and additional breedings are needed to develop a working genetic theory on the 'Moons'. Additional breedings are in order as well as the emergence of genome testing possible. While each year there seems to be a new novel mutation in the fancy, the research and testing for the moons is a serious undertaking for the handful of breeders currently working with it and there is statistical significance and characteristically unique for Moon to be considered for a new variety. Where this road will led us is a genetic mystery at the moment but one worth traveling down."


The following information is from one of the ratteries we work with. As we find out more we will make the information available. The photo in the blog is of two Moon rats, showing how the color can vary.

Moon Rats
Moon Rats