American Fancy Rat & Mouse Association

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

Colors & Coats

Darkening Siamese; Blue Point Siamese; Fertility Mystery
Darkening Siamese

Nicole Fadala
QI was wondering what would be the best color to breed with my Siamese rat. Would breeding to a Black Self be a good choice? I thought that might make the points darker on the babies.

Seal Point Siamese Rat

AA really good Self Black is an excellent cross with a Siamese. It does tend to darken up the points and if you are having problems with white feet, a really good Self can help there too. Ideally a Black used to improve Siamese should have dark pigment all the way down its feet and toes, and should be a deep, unsilvered black. Unfortunately, Blacks this good are very difficult to find. When considering a cross for your Siamese, no matter the color, it is of major importance to be sure the feet are not white. Once you have bred white feet into a Siamese, it is very difficult to eliminate this fault.

When you breed your Siamese to your Black, you can expect the litter to consist entirely of Black babies (unless the Black parent has Siamese in its background). If you then breed these babies together or breed one back to its Siamese parent, you will produce babies with improved points. This also holds true when breeding Siamese mice.

Blue Point Siamese

Deric Auston
QI have been breeding Seal Point Siamese mice for some time. I am intrigued by the idea of creating Blue Point Siamese. Are they attractive and worth producing? What is the simplest method of creating them? Though I do not live near any shows, it is important to me that I produce mice that are of good enough quality so that I could show them. With this in mind, what tips can you give me on Blue Point Siamese?

ABlue Point Siamese mice can be very attractive and certainly are worth producing if they strike your fancy. Typically they appear pastel in comparison with seal point mice. The AFRMA standard describes them as: Blue Point Siamese mouse “Color to be a silvery blue (bluer the better), as even as possible over the entire body. The shading to be gradual over the saddle and hindquarters and being darkest at the tail root. The belly should be as near as possible in color and shading. The points (nose, ears, feet, tail, and tail root) to be a medium slate blue. There should not be a definite or distinct line of demarcation but rather a toning in or merging with the remainder of the coat. There should be no white hairs, blotches, streaks, or mealiness of the color.”

There are two main ingredients in the “recipe” for making Blue Point Siamese mice. You need one Self Blue and one Seal Point Siamese. It is important that the Blue be a Self, because if it is marked, you will end up with marked Blue Point Siamese mice. Not only can these not be shown, but they would not be very attractive.

Once you have these, producing Blue Point Siamese is simple. Breed the two mice together. Most likely they will produce all Black babies. Keep the two Blacks that have the best color, and the most pigment on their feet. Breed these two together, and out of 16 babies you should get 9 Black Selfs, 3 Blue Selfs, 3 Seal Point Siamese, and 1 Blue Point Siamese. Though this is the proportion you should get, genetically speaking, it seldom happens unless you are breeding in huge numbers. You may get lucky and get Blue Points in your first litter, or it may take several breedings.

Blue Point Siamese mouse

The Blue Point Babies are easily distinguishable from their Seal Point littermates. They are a much lighter color from the time they start getting fur. They also tend to look gray rather than brown.

Once you have a few Blue Points, you can begin selecting for the best color, type, and temperament. This is a fairly simple process. When you breed two Blue Points together, they will produce all Blue Point babies. You will want to select the ones with the darkest color. This difference in color becomes apparent as early as 1–2 weeks. Watch these babies until they are 5–12 weeks old. From this group choose the ones that are the largest, have the nicest ears and tails, and have the best temperaments. These are the ones to keep for future breeding.

If the Blue Points you get are very pale and washed out, outcrossing to a nice Black can greatly improve the color.

There are a number of faults to look for when breeding Blue Points. It is best to avoid breeding animals with these faults. According to the AFRMA standard faults are, “Mottled color on the body; body color too light so as to resemble the Blue Point Himalayan; body color too dark so as to lose the contrast with the points; points too light; nose marking extending above the eyes.” Mottled color usually is the result of an animal which is going through a moult. This is a normal process and the color should even out in a few weeks. Once in a while a Blue Point will “stick in moult.” In these cases the animal’s coat remains blotchy. Sometimes a change in weather or temperature can help these mice. In other cases it is permanent and nothing appears to have an affect. Often this is genetic and these mice should not be used for breeding.

There are only three disqualifications for Blue Point Mice. They are: “white feet, white spot on the body, white on the tail.” Naturally, mice with these problems should not be kept for breeding. The most prominent problem is white tail tips. Consistently selecting against these will reduce the number of occurrences of this problem; however, almost all Blue Point litters contain a few babies with white tail tips.

One final point to remember about all Siamese animals is that their color is temperature dependent. The cooler the temperature, the darker the Siamese. The best time to show Siamese is during the winter when they are naturally darker. If you are attempting to competitively show Siamese mice during the warm months, it is best to bring them into an air-conditioned area. Be careful though, mice don’t appreciate being chilled too much (mousesicles), and it can make them sick if they are kept at too low of a temperature. Nichole Royer

Fertility Mystery

Sally Bennett
QI have a bit of a mystery with my mice. I have a group of gorgeous mice which are proving to be very difficult to breed. I am not sure why, since they are very healthy. They appear to have a fertility problem. My male is white with bright orange patches all over. He is a Satin. I also have three females, one is yellow with a white belly, one is pure white with black eyes and Long Hair, and one is a burnt orange. They are all related, and in an attempt to breed more like them I have been breeding them together. To date this has met with little success. The male has been in with the females for 2 months and so far neither the yellow or the white female has had babies. The orange female has, but both her litters were very small (one litter had 4 babies, one had 5) and only two of her kids are orange.

The litters these mice came out of also included a number of other colors like brown, black and white, and a light tan, none of which have any problems having litters. Also, both the yellow and the white female are rather fat, and the male and the orange female are somewhat portly. None of their brothers or sisters are. I feed them the same food as my other mice, and they all have wheels. Could this be the reason for the problems?

AThanks to your description of your mice, it is relatively easy to figure out what is causing this problem.

From your description I would say your females are a Cream Fox, a Black-Eyed White, and a Red. Your male is probably either a Red or a Fawn. All of these colors have one thing in common, they are caused by the dominant yellow gene. The Red color is a combination of dominant yellow and chocolate, Cream is a combination of dominant yellow and chinchilla, and Black-Eyed White is a combination of dominant yellow and the extreme chinchilla gene (Beige).

The dominant yellow gene has several quirks that often drive breeders crazy. It is often referred to as the “fat” gene, since most dominant yellow mice are overweight to some degree. This can range from being a little chubby, to being grossly overweight. This happens no matter what you feed them and how much exercise they get. Since overweight mice have very low fertility, this is probably the cause of the problem. Often, dominant yellow mice must be bred very young, before they put on much weight.

Many lines of dominant yellow mice tend to be very prone to tumors. Their obesity most likely has much to do with this, since overweight rats and mice run a much higher risk of having this problem. For this reason, it is particularly important to not feed these mice high fat foods such as seeds and dog food. Instead, feed a high quality lab block diet supplemented with the occasional treat of whole wheat bread, pasta, or fresh fruit.

Dominant yellow is also referred to as “lethal yellow.” This is because any mouse which inherits the dominant yellow gene from its mother and its father will die and be reabsorbed very early in gestation. Therefore, any time you breed two dominant yellow mice together, one-quarter of their babies will never be born. Because of this, if you breed two dominant yellow mice together, you will automatically get a small litter. Also due to this, you can expect a number of the babies to be some color which is not dominant yellow. *

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Updated December 28, 2014