American Fancy Rat & Mouse Association

This article is from the Winter 2000 AFRMA Rat & Mouse Tales news-magazine.

Brindle Mice

By Nichole Royer

Brindle Mice
Brindle Mouse
This is “TR Buba,” a light colored Brindle, owned by Nichole Royer.

One day, almost 4 years ago now, I came across a mouse in a pet shop. This little critter was a distinctive sooty gray color with clear black lines running across it like the stripes on a tiger. The tiny 3-week-old mouse was adorable, friendly, and appeared to befemale — just what I needed to be a companion for my Blue Point Siamese girl, Blinken, at home.

Blinken and her new friend Duffy settled in happily. Several weeks later I picked up Duffy and noticed the distinctive odor of male mouse. A quick peek underneath confirmed that I had once again failed sexing 101.

I quickly set Duffy up in his own home, but alas was too late. Two weeks later Blinken presented me with a scant handful of pink peeping babies. Quite to my surprise, most of the babies had the distinctive tiger stripes of their dad. I was intrigued, and this interest was the springboard to launch me on a project that has fascinated me ever since.


Viable Yellow (Brindle) mice were first reported in the scientific literature in 1962. They appeared suddenly in the C3H/HeJ strain of laboratory mice.

Within the fancy there is not much known about the history of Brindle mice. They predate my interest in the fancy by quite a number of years. The first Brindles I came across when I first started showing, were being bred by Karen Robbins. Hers came from Betty Aalseth at LabPets, a commercial breeder who bred animals for the pet shops and laboratories, in 1983. It is unknown if they originated in Betty’s stock or if she got them from a laboratory strain. It is entirely likely that they were one of those happy accidents that someone came across in a pet shop.

The first Brindle mice were shown at an AFRMA Show by Karen Hauser (Robbins) July 21, 1985. On July 13, 1996, they were officially standardized. To date there has been only one Brindle to go Best In Show and that was on March 13, 1999; my own Red Dilute Brindle Standard boy “Tarot’s B-Bop’n.” There have been several Section and Variety winners.

The Color Brindle

The AFRMA standard reads, “BRINDLE – Color 25, brindling 25. Brindle mice will be colored like brindle dogs or tigers with dark tiger-striping from head to tail tip and to a lesser extent on the belly. Background to be a recognized color. Eye color to match. Faults – Sooty body color to blend in with the brindling; brindling too light or too few stripes; brindling too heavy to lose striped affect.” This description is very apt. Essentially, they should be a colored mouse with dark stripes running across the back and head. They also should have some stripes on the stomach, and may have a hint of them on the ears, feet, and tail as well.

Brindle mice vary greatly in the cleanness and clarity of their stripes. They can range from mice with so much black ticking (sootiness) in their colored areas that their stripes are barely discernible, to beautifully clear-colored mice with stripes so light you can barely see them. Naturally, the ideal is somewhere in between — nice distinctive dark stripes with clear color between.

While the standard allows any recognized color as a background, in truth there are only certain colors in which you can get Brindle mice. Though the brindling trait only shows on mice that are genetically Fawn, this still allows for a wide variation in color.

Fawn/Black Brindle By far the most common, the basic color for Brindle (with no other colors acting on it) is a fawn (orange) background with black stripes. These look very much like tigers.

Fawn Brindle mouse
This is a Fawn Brindle “Tarot’s Variety.” owned by Nichole Royer.

Red/Chocolate Brindle With its spectacular background color, Red brindles can be truly beautiful. These mice have a red background color almost as intense as that of an Irish setter dog. The stripes on true Red Brindles are chocolate, and though this makes them less distinct than black stripes, they can be bred to be dark enough to have good contrast. These mice are particularly attractive when they have Satin coats.

Red Brindle mouse
This is a Red Brindle with chocolate stripes “Tarot’s B-Bop’n,” owned by Nichole Royer. The only Brindle to win BIS. “B-Bop’n” shows the typical “English” type — long body, long thick tail, large ears, and short sleek coat.

White Brindle mouse“Tarot’s White Out,” owned by Nichole Royer, a B.E. White Brindle with beige stripes.

White/Beige Brindle Though perhaps not as flashy as their orange/red counterparts, white brindles can be lovely in their own right. They are caused by the gene that cause Beige, bleaching out the orange on the mouse and turning it white. It also turns the stripes beige. Thus you end up with a Black-Eyed White mouse with pastel stripes. This is the one color of Brindle that you can’t see their stripes when they are just a few days old.

Silver Brindle Duffy was a Silver Brindle, and to this day I’m not sure what causes this color. He had one son that was this color, and I have not had one since. It’s a very pretty color with an almost Chinchilla look to it.

Gold/Blue Brindle Very pastel in shade, Blue Brindles have a pale cream/gold background color, with blue stripes. This is another color that can be spectacular in Satin.


Type is a term used to describe the general appearance of a mouse — the way it’s put together. Standards call for a large racy mouse (5½–6 inches without the tail) with elegant tulip shaped ears and a whip-like tail. Over the last 100 years the folks in England have reached this goal by breeding mice who truly live up to the standard.

Chinchilla Brindle mouse “Duffy,” Nichole’s original Brindle, a Chinchilla Brindle. Duffy had very poor type — short body, thin stuck-on tail, small ears, and rough coat.

Unfortunately, the mouse fancy in America is far behind. Not having had 100 years to selectively breed mice, most of our mice have pitiful type, not having been bred with selection for type in mind. Most mice originating in pet shops and many fanciers mouseries are very small (2–3 inches in the body), have tiny round ears, and tails that look like they were stuck on as an after thought. Many also tend towards jumpy and nippy temperaments. Being a true American breed, most Brindle mice clearly fit into this description (my Duffy being a classic example).

Fortunately, this is simple to remedy. Brindle is dominant, as is the fawn gene. If you breed Brindle to any other color, you should get Brindle in the resulting litter. Ideally, breed Brindles to English mice with nice conformation. This will greatly improve the type of the resulting Brindle babies. Doing this over several generations results in Brindle mice with English Type (it’s taken me 4 years).


Brindle mice are genetically Viable Yellow (Avy). This places it in the “A” series of mouse genes. Brindle is dominant to every gene in that series except Lethal Yellow (Ay). Like Ay, Avy causes a tendency towards obesity. This can range from slight portliness in some mice, to extreme obesity in others.

Fawn Brindle Long Hair mouse One of Karen Hauser’s (Robbins’) Fawn Brindle Long Hairs in 1984.

I have to add a qualifier here. Though I have been told that Brindle is dominant to every gene other than Ay in the A series, at least with my mice that is not completely true. I have found that Brindle (Avy) is not fully dominant over Tan (at). Mice that are AvyAt are clearly Brindle on top, but lack any striping on their bellies. When bred to each other or to non-tan selfs, Tans and Foxes of various colors are produced. Brindles who do have striped bellies do not produce Tan/Fox youngsters.

One of the fun things about Brindle is that you can get it in a number of different colors. For those interested in breeding these colors, the genetics are fairly straight forward.

Brindle Color Description Genetic Code
Fawn/Black Orange with black stripes Avy_
Red/Chocolate Red with brown stripes Avy_bb
(combining Brindle &
White/Beige White with beige stripes Avy_cece
(combining Brindle
& Beige)
Silver White or pale cream with
black/dark gray stripes
not sure, quite possibly
(combining Brindle
with chinchilla)
Gold/Blue Gold with blue stripes Avy_dd
(combining brindle
with blue)

These represent the color combinations that I have tried or had pop up. There are many others that could be experimented with, and I couldn’t begin to predict the results.

English Brindle

Some confusion has arisen about the genetics and health problems of Brindle mice. Much of this is caused by the fact that there are two genetically different mice which are called “Brindle.” To the best of my knowledge, the folks in England do not have the tiger-striped color we call Brindle. Instead, they have mice that have an interesting pattern (almost like a tortoiseshell). This color is lethal when seen on male mice, and they die very shortly after birth. Examples of these mice do exist here in the United States, though not apparently on the west coast. Genetically, England’s mice are what the scientific literature refers to as Brindle. The American version, however, comes much closer to looking like the brindle seen on other species.

Breeding Brindle

Producing more Brindle mice is, fortunately, very simple. Brindle is dominant, so any time you breed a Brindle, you should get some Brindle babies in the resulting litter.

The best mice to keep for breeding are those that come closest to meeting the standard. Sootiness is very difficult to eliminate, so I always prefer to err an the side of having clear color and light or scanty stripes. I have produced as many nice Brindles out of Brindle/non-Brindle breedings as I have from Brindle/Brindle breedings. This is one reason Brindles are so nice to work with. Their major problem tends to be their type. The easiest way to improve this is to find an English male with exceptional type and send your females to him. My best Brindles have all been fathered by Best in Show pure English Pink-Eyed Whites and Beige Fox Satins.

Brindle mice
A female Fawn Brindle “Tarot’s Variety” and a male Red Brindle “Tarot’s Sunnydale,” both owned by Nichole Royer.

The best time to make your pick out of a litter of Brindle babies is when they are about a week old. At this point their stripes will be distinctive. If you cull, this is when to do it. Often, babies get sooty by the time they are 4–5 weeks old. Their good color may not reappear for another 3–4 months, so it’s worth taking a good long look at those week-old babies.

Due to their tendency towards obesity, Brindle mice should be bred at a relatively young age. Many people find fewer problems and higher fertility if they breed their Brindles well before they reach 3 months old. Diet can also play an important part in fertility.

Showing Brindle Mice

Brindle mice are a fairly simple color, and a good one will do well on the show bench. Type and clarity of striping are the two things a judge will particularly look for.

Because all Brindle mice tend to be portly, it is important to keep them on a nutritious diet (lab blacks) with no “junk” food. Stay away from grain-based diets, nuts, and dog food. This will also greatly reduce the incidence of tumors in these mice. It is an unfortunate fact that Brindles are genetically predisposed towards tumors. For this reason it’s also a good idea to see that Brindles have access to a wheel or are kept in a large cage which encourages them to exercise. The lower their weight, the less chance of problems.

Because they are genetically fat, Brindle mice will never have the stunning type of some of the self colors. Almost all will have a bit of a pot belly at the very least. This, however, is no excuse for poor type. There is no reason Brindle can’t have elegant ears, big eyes, long bodies, and well set-on whip-like tails.

Brindle mice
One of Nichole’s Cream Brindles. This mouse needs improvement in type but has fairly clear stripes.

Judges will closely look at the striping on Brindles. Ideally, the stripes should be narrow and evenly spaced. They should be balanced (one side of the mouse shouldn’t have more stripes than the other), and clearly defined when compared to the background color. The standard calls for stripes on the belly (though there are those of us who prefer a clear belly).

All and all, Brindle mice are an excellent variety for most fanciers. They can be successfully kept and bred in small numbers, and are easy to breed with good results, so they are a good choice for novice fanciers. They also provide an interesting challenge, come in diverse colors, and have a complex genetic make-up, so advanced hobbyists enjoy them as well.

  • Bonnie Walters’ “Mouse Genetics Series.”
  • Letter from Bonnie Walters, May 10, 1996.
  • Silvers, W. K., The Coat Colors of Mice, a Model for Mammalian Gene Action and Interaction. Springer-Verlag, New York, 1979. [Thank you to Wanda Wilson for a copy.]
  • Karen Robbins *

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Updated November 6, 2014