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

By Karen Robbins

Amy Williams, Camarattery, CO, e-mail
QI hope you don’t mind me asking a genetics question. I have always wondered how do you get a head spot on a Berkshire. I have never worked with the correct marking on a Berk. And I have wondered what gene causes that. Where does the gene come from in the first place? I know you can make a Berkshire have a head spot from high white lines or from recessive blazed lines. But I don’t know if there is a better, different, or correct way to get that gene. Thanks!

AThere is an article on the head spot (hs) gene Brief communication. Head spot and dilute mutations in the Norway rat (or the full PDF article) that tells about it. It is recessive and they were basically head spot Berkshires or in the test breedings with Hooded they produced head spot Hooded. With straight Hooded Berkshires (Hh) they don’t have the head spot so the gene has to be introduced to get it. Also, their belly markings aren’t usually covering the entire belly that the Standard calls for. With the Berkshires out of Variegated or Dalmatians, they always have a head spot and a lot more white on the belly. Also, with Essex, they always have a head spot as part of the pattern. However, head spots can also change into Blazes or crooked stripes (a.k.a. slash blaze, stripe blaze, lightening blaze, crooked blaze, streak) up the face which is also common in Variegated. One breeder of Essex just got two very nice Blazes in her latest litter—had always been head spots in the past. Since Essex is not a spotting gene, you can’t get the head spot without the Berkshire pattern and the whole Essex fading color. With the head spot Berkshires out of Variegated it is easy enough to get the markings in other colors. With a little work you can straighten up the demarcation lines (they usually have uneven edges to the white belly marking).

Telisa Overton, e-mail
QI have another question having to do with the male I’m planning to breed. I noticed 3 days ago that his Siamese markings have changed. The marking on his nose extended upward in between his eyes. I know that the Siamese coat tends to change with temperature, but the most dramatic change I’ve seen before this was the coat getting lighter. It got darker and extended a lot this time. But what I thought was kind of strange was that in the extension on his face, there is now a white L-shaped marking. He’s a little over 1 year old and has never shown any markings like that. He has two white feet but the lighter markings on his face have never been there before. I didn’t know if it was because of the temperature change or that he could be molting. His back end shows no patchiness or molting at all. That area’s still the same as it has been since his first molt. His babies with the Black Berkshire female ended up being mostly black, except for one with a wonderful Berkshire marking and a few others with some white toes. I got him as a gift from my friend who kept three of his brothers and none of them have shown anything like this. Half of her litter was Siamese, one baby was Chinchilla, and the rest were Black. The Chinchilla is a Dumbo with a nice Berkshire belly and a lightning blaze on his face.

Is it possible that my male could have the Variegated blaze even though he’s never showed it before?

AYes, your rat is a marked Siamese since he has white feet and most likely has white on his stomach. With Siamese, markings won’t show up very well because of the light body color so you normally only see them on the face, feet, or butt where the point color is. I’m guessing his black siblings also have some amount of white on them? Marked Siamese will show their markings in the nest (best place to see any markings since the body color is a brown color) or when they get older (markings are usually only seen on point areas unless they have really dark body color for a Siamese). The best guess as to the type of markings he has is to look at the black siblings—do they have various amounts of white on their bellies/chest area, any with markings on the back or head?

When Siamese rats molt for the first time at 6–8 weeks you will see the brown baby coat change to the light beigey color of the adult. Ten to twelve weeks is the next most notable molt for some colors of rats. With Siamese, the males will have the better color and will get darker as they get older. For a marked Siamese to show a head spot (which either Berkshire or Variegated rats will normally have), the color on the head needs to be dark enough to see.

In the photo it looks more like your rat is molting or the way the color is rather than a white marking.

Kayla Freier, Facebook
QRe: Photo on AFRMA Facebook page of 3-month-old Black Berkshire male rat taking a bath. Wouldn’t he be considered Variegated because of the white spot on his head? I’m still getting to know recognized rat colors and markings so feel free to correct me if I’m wrong.

ABerkshires are supposed to have the white spot on the head and the ones out of Variegated or Dalmatian breedings will have this. Berkshires out of Hooded breedings don’t typically have the white head spot nor as much white on the belly. You can read more about Variegated/Berkshire in these articles:

• Variegated X Self = Berkshire, not Variegated
• Difference Between Dalmatian and Variegated Rats

One way to remember the difference between Variegated and Berkshires, Variegated rats are more similar to Hooded but have white and color splotches on the back with the solid head/shoulder area, where Berkshires are all color on top with a completely white belly (similar to a Tan/Fox mouse).

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