This article is from the WSSF 2012 AFRMA Rat & Mouse Tales news-magazine.

By Karen Robbins

Holly M. Sherrah, Canada, e-mail
QMy AFRMA calendars have finally arrived! They are beautiful!! It’s a very bittersweet keepsake, as I have lost both of those sweet ratties since entering the calendar photo contest. [Rats appeared in several months, Ed.]

Why was my boy Rodney’s breed description changed? When I filled out his entry forms, I provided his breed information as it appears on his pedigree. I was quite surprised to see that it was completely changed. Though I agree that he does closely resemble a Variegated rattie, I can’t understand why he should be listed as just Blue instead of American Blue.

ABlue is the same genetically here or in England (we use gg for the code where they use dd). England now calls theirs British Blue but it comes in the same shade variations and some have the lighter undercolor as over here (they want theirs in a dark shade with no undercolor which is the same for our Blue). AFRMA recognizes two shades of this gene—Sky Blue for the medium most common shade, and Blue for the dark version (you have to selectively breed to get the dark version and without the lighter undercoat). Some breeders call this gene American Blue (referring to different shades though) others Blue, but it is all referring to the same Blue gene. There is no separate unique American Blue gene.

AFRMA imported Variegated into this country from England in 1983. It is a unique pattern (we did almost 3 years of extensive test breedings from animals with known backgrounds to try and determine what it is genetically and came up with the conclusion that there are several genes that work in combination with each other and linkage may be involved, so it is not a simple gene as most sites list it as) that is very distinct and will always have a star/head spot or blaze (ranging from a stripe to half/full white face), white under the chin/throat/chest area (unlike a Hooded rat that has a colored chin/throat/chest area), and splashes on the back that can range from no/very few splashes, to splashes with some solid areas, to be so heavily marked they have a solid patch on their back/butt with just a little brindling/splashing on the edges. When breeding Variegated to Variegated you always get the same type of markings in the litters—head spot Berkshire and Variegated, sometimes Capped or mis-marked Variegated, but never Self or Hooded. Breeding mis-marked Variegated or Capped-type from these litters can be a way to make Masked. Breeding Variegated to Hooded just condenses the pattern to the spine area only instead of over the whole back and sides like it should be, and you will get both markings in the litter which shows they are different genetically. We’ve seen many breeder sites list Variegateds as Bareback, Hooded, Dalmatian (Dalmatian is a dominant gene that works with Variegated but is not the same), mis-marked Hooded, Capped, Capped/Bareback, mis-marked Capped or Bareback, Baldie Dalmatian, Roan, etc. Your rat is a light marked Variegated and the description on your application (Bareback/Dalmatian with Essex head spot) does visually describe what he is but Bareback, Dalmatian, and Essex are three separate genes, two of which are dominant (Essex is a color fading gene that has a Berkshire pattern but it is not caused from a spotting gene). We have an article on our web site Difference Between Dalmatian and Variegated Rats that tells about Variegated vs. Dalmatian.

Sorry to hear of the loss of both of your rats. We all loved the winning Christmas shot and you did a great job coming up with the props for the various themes! The rats looked like they enjoyed all the various themes you came up with. We look forward to seeing your new rats for next year’s Calendar submissions. If you have further questions, let us know.

Update: My knowledge of genetics is fairly basic, so that was very informative! Do Variegated ratties typically grow more spots and splashes of colour as they age? When Rodney was a baby, he had very few spots, but developed more as he got older. By the time he was an adult, I thought he looked much more like a Variegated rattie than a Bareback as his pedigree stated! Also, about the headspot: I was told that a triangular-shaped headspot was referred to as an Essex Headspot, is that not true? Holly

AIn answer to your question on the head spot on Variegated, AFRMA’s standard states: The head and shoulders to be solid like those of a Hooded rat with a white spot/star on the forehead which should be centrally placed, round or oval in shape, and no bigger than the rat’s eye. We base our standard on the N.F.R.S. in England since we imported them from there in 1983. However, the head spot can range in shape from a narrow stripe to a large round spot and is only 5 points in the overall markings. Ideally, we want round or oval in shape but have seen many shapes and sizes. With Essex, they have the same problems with their head spot being odd shapes, but as one English breeder of Essex described, The headspot should be the shape of a rain-drop. Baldie rats (now referred to as Essex Capped in the N.F.R.S.) which come out of Essex breedings and are similar in marking to a Capped, are to have a large white triangle between the eyes with a white line running from the point of the triangle to the white on the neck.

Sometimes light marked Variegated can get more colored hairs than what they had when they were very young babies in the nest, especially if they are just a few colored hairs showing up. Though usually what markings they have by 8 weeks, is what they will have as adults.

Bareback rats come from Hooded stock and will have the colored chin/throat/chest area and no head spot. There are some good research articles on Hooded:

• High-Resolution Linkage Mapping of the Rat Hooded Locus. Torigoe D, Ichii O, Dang R, Ohnaka T, Okano S, Sasaki N, Kon Y, Agui T. The Journal of Veterinary Medical Science (J Vet Med Sci.), 2011 May;73(5):707–10. [talks about the Kit gene, Ed.]
• Piebald Rats and the Theory of Genes. W. E. Castle. Proceedings of the National Academy of Sciences (Proc Natl Acad Sci U S A/PNAS), 1919 April; 5(4): 126–130. [has drawings of grades of Hooded, Ed.]
• Variation in the Hooded Pattern of Rats, and a New Allele of Hooded. W. E. Castle. Genetics, May 1, 1951, vol. 36 no. 3 254–266. [has same drawings of grades of Hooded as 1919 article]
• Linkage of hooded and hood-modifier genes in the rat. V. Stolc. Journal of Heredity, 1984:75(1):81. [talks about Hood-modifier gene—short and long, Ed.]

A Russian Blue Agouti Essex Standard showing the typical head spot that Essex have. Rat owned and bred by Mayumi Anderson.

Since Essex is a color fading gene and not a spotting gene, the head spot and Berkshire pattern are not reproducible onto other types of rats. Breeding Essex to other rats is the same as breeding to a Self, as breeding Essex to Self gives you only Essex and Self, not various types of markings like what happens with a normal spotting gene.

There is a separate recessive head spot gene that could be combined onto other types of rats so if you had this gene, you could make head spot Hooded or other types that normally don’t have this marking.

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