American Fancy Rat & Mouse Association

This article is from the Jan.-March 1994 AFRMA Rat & Mouse Tales news-magazine.

Colors & Coats

Reverse Siamese Mice; Hidden Treasures (Blue Recessive Yellow)

By Troya Duncanson

Reverse Siamese Mice; Hidden Treasures (Blue Recessive Yellow)

From Wanda Wilson, New Cumberland, PA

Q I’m very interested in your Reverse Siamese mice (saw it just got standardized). I have them too, and they win Best Potpourie ribbon (stupid name—Unstandardized is better) but they are little round string-tailed Frizzies—very American. We have two mouse classes, so most of the people who compete that have limited access to English stock can compete. I’ve tried outcrossing and seem to lose the Reverse Siamese aspect and never get it back, or they just don’t breed at all. They aren’t hardy anyway and get Frizzie Rot, though I’m getting some success in breeding that out (Ivermectin and cold-hearted culling seems to help). The Reverse Siamese pictured (N/D93:14) is BEAUTIFUL! Mine look like they’re made from used craft shop pompoms! What gene/genes are responsible, which chromosome, obviously really recessive, what can you tell me?

My Hidden Treasures (Blue dilution of recessive yellow) are doing fine, but we can’t figure out what category to put them in. They look like reverse Argentes, so Banded comes to mind, but Blue mice, same mechanism, but with black pigment are standard coats. What do you suggest?

A I have already addressed the genetics of Reverse Siamese for a previous question (N/D93:14). I will mention that I believe I get the highest contrast with pale noses due to the extremely dark pigment factors that came with the English stock. Cross-breeds tend to be simply shades of Beige or Coffee, unless that dark pigmentation is preserved on the basic Chocolate.

I’ve heard of English/American crosses having fertility problems, but my worst fertility problems have been with certain strains of pure English. Suggestion: When outcrossing, cross to a pure dark lineage Siamese. You will be able to identify at all stages which mice are heterozygous, which are pure Siamese, or pure Beige/Reverse Siamese. (You can do the same with albino, but I challenge you to find a darkly pigmented albino!)

As to how to categorize Hidden Treasures, I imagine they would fit into Any Other Color (AOC) if AFRMA standardized them. I have also heard of ticked as a category (contains Agouti, Argente, etc.). Pearl and Opal would fit into these categories (light color with dark tipped hairs). *

Back to top

October 27, 2018