This article is from the Holiday 1997 AFRMA Rat & Mouse Tales news-magazine.

By Minna Piippo

Original version written by Minna Piippo. Published in Haisulit (mouse)-section of Finnish Fancy Rat Society’s newsletter Rattus 1/94. Translation, editing, and additions by Satu Karhumaa.

A red colored mouse

Red is one of the oldest colors in the mouse fancy. “Yellow” mouse was known during the Han-dynasty in China at about 80 BC and the British National Mouse Club acknowledged the red mouse in its standards of excellence in 1895. However, at that time the name of the present Red was Fawn. When the red-eyed variety of the this red mouse was developed, the original black-eyed variety gave its name to the red-eyed variety and the original color was given the name Red.

The color of the ideal Red mouse is deep red, eyes are black. Most common faults on a Red are too light a color, which usually goes hand in hand with obesity, and sootiness. Sootiness means the considerably darker, dark brown or black coloring on the mouse’s feet, head, ears and back. Usually the pigment on a very sooty Red is apparently darker than on normal Reds.

An obese Fawn Mouse

Obesity is one of the hardest problems with the Red mouse, causing does to be infertile and difficulties in giving birth. Does are more prone to obesity than bucks and it is quite usual that the light colored, almost Fawn reds get to be the fattest. Because of these troubles, Red females should be mated for the first time at a relatively young age of two months. When bred for the first time at the normal age of 3–4 months the female may not get pregnant or if she does, she may have difficulties in giving birth. This is true with the fatter Reds; normal-bodied do not get these problems so easily.

The gene responsible for Red is called lethal yellow (A^y), which is the top dominant of the Agouti series (A). The gene is dominant, but lethal — A^y A^y fetuses die on the 6^th day of pregnancy.  Proper Reds are genetically chocolate, A^y* bb (possible combinations are A^yA, A^ya, A^ya^t). In addition to this, the intensity of the red coat color is probably dependent on intensifiers, analogous to, but distinct from the “umbrous” genes. Due to the dominance of the lethal yellow gene, the phenotype of an Ay mouse is either a rich yellow or orange color, or sooty red or sable—depending on the background (= other genes involved).

When breeding Reds, you should aim for good coloring as well as type and size. Red mice are usually smaller in size; they have smaller ears and a bit poorer type than many other varieties. This is caused by the genes involved with this color. It is not one of the hardest colors to breed, but it does take time, sustained effort and a careful breeding program to succeed. Red is best mated with another Red, Cinnamon, Chocolate, or Chocolate Tan. Any other colors are not advisable to use, as they will produce Reds that are not really of any particular color. Best Reds have no black, blue dilute, or silvering genes involved.

Best combination with Reds would be Red to Red. However, this results in a litter with 25% less babies than normal.  By combining the best Reds together you will be able to maintain the color of your breeding stock well. Do not use the light-colored, obese, or sooty Reds for further breeding.

A Sable Mouse

When you wish to get larger size to your Reds, you can use Red to Cinnamon matings. Using Cinnamon or Cinnamon Tan too much will however bring along sootiness to Reds. Red to Chocolate or Chocolate Tan does also work without giving too much sootiness. Tan helps in giving a better, deeper belly color, if this is lacking in Reds.

Reds can be used to improve the red shade in Agouti, Cinnamon, and Sable, giving them evenness. Usually Cinnamons and Agoutis born from Red lineage are of good color, but poorer type and size. Reds born from Sable lineage shouldn’t be used for further breeding of Reds due to the sootiness brought along from the Sables. However, you should bear in mind that using Red too much will bring along the usual faults of this variety; small ears and type and prone to obesity.

Tony Cooke: Exhibition and Pet Mice
Roy Robinson: Colour Inheritance in Small Livestock
Willys K. Silvers: The Coat Colors of Mice

See the AFRMA Standard for Red.

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