Shadow/Tort Info

The “Tort” Genome

This page is to help inform people on this rare genetic trait, Please read through it, its very informative! I have also included PDF files on this genome! Enjoy! Any questions please PM me.. I’ll try to keep this as updated as much as possible as I continue to work with this Genome.

There never seemed to be enough info on this gene, so I’ve decided to make sure to put this info out there for other breeders who may have been able to stumble across this very old genome, or received it from a fellow breeder. Please note, that this information may or may not be 100% accurate and possibly is missing information here and there, I have tried my best to ensure that what I have complied here will help other breeders who are working with this gene are able to use said info to breed their “Sand” genome rats to the best of their ability.

The first time I came across these rats was by browsing the web many years ago back in 2003, when I stumbled across Rats’n’Rave Rattery in Michigan, the breeder Tami was working on a very rare Tort genome that was intriguing to me at the time, I just recently found out that this is in fact the “Sand” Genome. She shared her rats with Alan from 6th Happiness Rodentry, who has helped me immensely with information, and guidance. He in turn shared his rats to Robin who passed away unexpectedly , she ran Deer-Creek Rattery. I have been able to receive information from her site and have added it via a pdf file.

The “Sand” Genome is the only genome to-date that will produce uniquely colored rats, such as Tort, Shadows, Caramels, Midnight Blues, Black Eyed Silvers and etc. The Genetics for these rats will be listed down below also ( again some of these may or may not be 100% I will update them if I find out more! )

All information on this page was given to me, or either found by me during my research of these rats, guided by fellow breeders who are helping me with this genome. ūüôā


Research Material I have found or what has been sent to me by fellow breeders to help me along with my rat variety


Genetics – Currently Known

I don’t claim to be a genetics expert, I have used these genetics and have changed and added to them to the best of my understanding of genetics while working with this variety.
**I will revise these genetics how I see fit for what works for me. 

Agouti Based

  • Aa – Agouti
  • A(m)a – Agouti Carrying Shadow ( Hidden not visible)
  • a(m)a(m) & a(m)a – Melanistic Agouti ( Non-Visible Shadow)
    ( Very dark agouti, almost black in appearance )
  • a(mo) – Mottled¬† (Recessive to A ; Dominate to a ) (Modifier of (mo) causes rats to tort over the extent of their life, starting around 6-8weeks of age, the color change is more pattern then shading.¬† Can start anywhere on the body is usually seen in a comets tail type of swirl,¬† changes belly to chocolate in some rats depending on the modifiers – seen in charcoal rats, eyes and nose on rats are pale.)
  • a(mo) sdsd – “mock” Agouti
    ( A black rat with a silver belly, rat slowly develops yellow ticking on its side which overtakes rat after each molt, Color can be a drastic change or sudle, Eventually said rat no longer looks black, but more agouti-ish over time, more yellow in appearance. )
  • ¬†sdsd – Sand ( Also produces Tort Effect )
    ( A genetically yellow agouti rat with the color resembling that of beach said, ticking is black but doesn’t stand out, uniform color through out, eyes black.)

Black Based

*sdsd – causes yellow banding in the fur turning rats from original color to a more yellow version.

*(mo) can present its self in any of these varieties and cause torting, it just depends on if a parent carries it. Seems to be a dominate trait.

  • a(m)a +unknown Modifiers – Charcoal
    ( a black rat that is born a shade lighter than a standard black, rat appears to have more of a blue hue, compared to black. as the rats develop fur they are noticeably lighter than a standard black. During development the rat develops a grey undercoat which lightens the color more, belly is an off black, darker grey color, shade varies depending on modifiers (red or dingy belly is a fault! and should be bred away from ) Color confusion can persist all the way into young adulthood due to the manner in which Charcoal rats molt. A marked Charcoal rat will produce a self or close to self offspring when paired with Berkshire.)
  • a(m)a¬† ??¬† – Midnight Blue
    ( Shade is lighter than black, but darker then RB, Midnight Blue and RB are not compatible and in pairing will only produce black babies!)
  • a(m)a mm sdsd rr – Caramel
    (Warm creamy yellow color, resembling tea with milk, eyes ruby, No ticking in fur, white belly fading to silverish creamy yellow up sides, under-coat white)
  • a(m)a sdsd rr ++ Steel Modifiers (ae^D) – Khaki
    (Tanned rat resembling khaki pants in color,  They are darker than beige,  and can not be mistaken as beige, as the rat ages it grows darker, undercoat to resemble top coat, fur has feathering of varies shades of the Khaki color with top coat presenting darker ash colored ticking.)
  • a(m)a dd ?? – Russian Midnight¬† ( More info required!)
  • a(m)a dd mm ??– Black-Eyed Silver¬† (More info required!)
  • a(m)a c(h)c(h) ?? rr – Midnight Point Siamese
    ( Rat has a grey shade to body, points to be off dark grey in color, no ticking, eyes Ruby)
  • a(m)a(m) & a(mo)a¬† ++ Modifiers¬† – Shadow
    (Rat is visually black in appearance, belly is silver/grey – color can range from very silver to darker silver depending on genetics – resembling that of an agouti, the silvering fades up the rats side. )
  • a(m)a(m) dd or a(m)a dd – Russian Blue Shadow
    (Rat is visibly an overly yellow ticked slate grey, belly is silver and fades up the sides, As a pup rat is born near Silver and goes through a phase of getting dark before it lightens with age as ticking comes in. )

Steel (Modifiers) –

Can be displayed on any color variation on the Sand Genome, Works like Pearl needs Sand based rats to display. All rats present a darker dorsal spine strip, Bellies vary from white, oatmeal cream, to chocolate depending on the main base color.

  • Modifier E^D (Recessive non-agouti, recessive to (aa) ) – Dominant extension of Black
    Causes the black bank on the hair shaft to spread and cover the entire hair giving it a dense blue-black appearance 
  • Modifier e- – Exclusion of Black
    – Causes the black band to be stripped from the fur, causing the rat to be paler in color, causes fur to go ash in color, giving a bluish-grey color.
  • A^w (Dom to AA & Aa ) – White-Bellied Agouti
    An agouti with non-ticked belly, color is white or off white, not the standard grey. Sides are yellow and fade to darker agouti, the dorsal area is darker ticked. Rat has a three-toned look.

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