How to Distinguish Champagne from Silver Fawn Rat

Left: champagne; Right: silver fawn

All rats either have Agouti- of Black-based colors. They are the most basic color any rat can have. Modifier genes are then introduced into the gene pool of the family to produce other colors. This includes the ruby- and pink-eye genes. 

What does the P-locus do? 

Here is an excerpt of the standard definition from AFRMA"

"This locus has a strong diluting effect on eye color and black/brown pigment, creating pink eyes and a pale yellow color. It only slightly affects yellow/red pigment." 

"In Black, Chocolate, Lilac, and Mink animals pp dilutes the color to various shades of Champagne (pink-eyed Blacks are show Champagnes). pp dilutes the black band in Agouti to champagne creating Silver Fawn and Amber (which is the same as Silver Fawn, just selected for a lighter color). Pink-eyed Blue (ggpp) is a white with a cool blue cast—a color we call Silver*."

Dominance of the gene modifiers 

Both of these genes are recessive, and therefore, will not be expressed physically (phenotype) unless the offspring has a double recessive combination or if both parents are 1) Pink-eyed or 2) Recessive carriers. 

The genotype would be ‘pp’ for pink-eye. 

Champagne vs. Silver Fawn 

Now that we know how these colors are produced, we can now easily tell which is which:

• Champagne is a light creamy beige color (the keyword is BROWN)
• Silver Fawn is more on the orange side (the keyword is ORANGE)