American Fancy Rat & Mouse Association

This article is from the WSSF 2009 AFRMA Rat & Mouse Tales news-magazine.

Colors & Coats

Black Rats and Silvering; Silver Black Rats

By Karen Robbins

Black Rats and Silvering

Candy Evans, NRMCI, New Jersey, e-mail
Q I have a question on Black in rats. You said that all Blacks silver with age. About when do they start silvering? Can they be born silvered? I had a Black Self Rex rat once that stayed very black for a long time before “graying.” She only had one litter of 4 pups—1 Black, 2 Blue, 1 Siamese. I saw her Black son when he was about a year old. He was still very black. I could not get the original pair to repeat the breeding so was unable to get more like the son.

Of all the other blacks I’ve seen out here in my neck of the woods, some were born with silvered hairs mixed in, some seemed to acquire them somewhere between about 3–6 months.

A Black is one of those colors that they either silver or turn brown. Even the extremely nicely colored ones will have a slight amount of silvering—just the way it is with rats. Some come in with a lot of silvering at 6 weeks in their first moult and it can diminish over time but they will still have some, others have some at 6 weeks and get more as they get older. The thing to do is to select for the least amount of silvering. If you get a really nice one like your female and she produces more really nice ones, then you would want to keep that line. I have a really nice Black male right now. His father was also a really nice black (no silvering). This would be a line to continue for the color as it was passed down. Most blacks that people have have silvering and so when they breed them, they are just making more that will have silvering. It’s just a matter of selection. As babies you can’t tell which ones will have silvering (more of it, or less). The only thing you could tell would be the intensity of black. One note about Rex that I’ve found is that they normally don’t get the silvering like regular coated rats and that is probably why your two Rexes had the nice color.

Silver Black Rats

Candy Evans, NRMCI, New Jersey, e-mail
Q I have a rat whose color I’m not sure about. Kishu has hairshafts that are a blue and the tips are black or really dark blue and dark (looks black) guard hairs, is silvered (has white/silver hairs sprinkled evenly throughout), and has Blazed Berkshire markings. The mother was an American Sky Blue Berkshire, the father is a Hairless Dumbo. Both have blazed faces and dark eyes. I don’t know the father’s genetic color background as I got him at about 14–16 weeks old and he had little hair. His fuzz is sort of brownish/blueish? I haven’t been able to get a hold of a microscope to snip any facial fuzz to examine. It looks to the naked eye like a coffee/lilac/buff sort of color. He and his brothers all had lighter skin (not pale like hairless PEWs or Beige).

Kishu, the rat in question. Owned by Candy Evans.

Mom had 13 babies. When they first got fuzz, three looked pitch black, eight looked slate/charcoal, and two looked blue. All were Berkshire—six had blazed faces. As they grew, the black got blacker, the slate/charcoal got darker—but you could still tell them apart from the black (although barely—blue tinted blacks), and the two “blue” got darker, but their hair is a variety of mixed hairs: blue, dark brown, silver. Very evenly mixed. Oh, the slate/charcoals are also very evenly silvered.

At about 10–12 weeks old, the litter was black, silvered black, and Kishu (and her sister) were this bluish-black color with the banding showing and ticking developing. The black babies (I have one) is still very black with only a little silvering. The silvered babies are very silvered, but not too much more than they were at 12 weeks old. I’ve enclosed a pedigree if this helps. What do you think?

A In the photo, Kishu to me looks like the Silver Blacks I get from the Dalmatian rats—I don’t see Blue in her. Although no where in the pedigree does it have any “Dalmatian” type rats. The Dalmatians have the charcoal/silvered color and sound just like you describe as babies.

The Blues with the dark brown and silvering sound like they could be Blue Agoutis.

When I did my English Russian Blue Agouti Essex and Silver Black Dalmatian cross, I came out with a Fawn, Russian Blue, Silver Blue Agouti, Black, and Silver Black. Essex is a dominant gene and Dalmatian is also dominant but the head-spot Berkshire pattern that the Essex has is not from a spotting gene, so it was as if I bred the Dalmatian to a Self. I was expecting lots of white markings but I just got messy EI/I/Berkshire-type markings (same as when I breed Dalmatian to Self)—none appeared to be Essex. I did get a Silver Black EI that when bred with Variegated, I got the correct Dalmatian show markings. Dalmatian is a homozygous lethal gene that “extends” the amount of white in the coat, creating silvering, and increasing white markings, so as long as the rat is Silver Black (no matter the marking) it is a Dalmatian; breeding with the Variegated breaks up the marking to be what we want for show.

There are the Roan rats (also known as Husky; a recessive gene) that are silvered but you can tell those apart from the Dalmatian Silver Black as the Roans get more silvered and lighter with each moult. Their pattern is always Berkshire-type (with or without a blaze—most have a blaze) or blazed striped/banded. *

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Updated January 23, 2015