Siamese and Himalayan - the Shades of the Rat

Kathrin Guttmann Shades / Shade, Knowledge, Breeding & Genetic

Already 1973 Moutier et al.1) R. MOUTIER, K. TOYAMA & M. F. CHARRIER (1973) , Himalayan allele at the albino locus in the Norway rat, Journal of Heredity, Volume 64, Issue 5, 1 September 1973, Pages 303–304 the occurrence of Himalayan mutation on the C-locus in a laboratory stock of fat rats.

The selective breeding of lovers Siam pet rats had 1978 Their origin. In September this year, Roy Robinson could, genetic advisor NFRS, three pairs or from a laboratory in Orly. Orleans (Various sources report different places) import. He was supported by a laboratory in Charshalton, where the animals were first housed. To finance the project, were options on offspring to ever 5 pounds sold, so that the first offspring from the laboratory just before Christmas 1978 went to members of NFRS.

At the time, however, the animals looked not like this, as we know Siam rats today. Rather, they resembled Hooded Silver Fawns with a distinct orange color and only slightly darker noses. From there it was still a long way to the typical Siamese rats of today and many of the breeders, the animals had received from the original litter, presented their efforts soon fell. By a cross with a Black Berkshire rat Hooded-drawing could be removed and the reddish color disappeared. However, the cross-breeding of Berkshire could not eliminate all the problems in the line, because it initially failed, to eliminate the white paws and tail tips. Using strict selection and the repeated crossbreeding excellent Black Self succeeded, Finally, to get the white markings on the toes and tails in the handle and extend the dark areas. 1983 eventually won two of Siam (Dusky Surprise und Dusky Princess) the first (Best in Show) and second prize (Runner up) in der Bradford Small Livestock Show. 1984 then became a born Bock, who finally had the darker belly, the one so much sought. In the US, the first eight Siam rats came from an import in 1983. Am 31.03.1984 they were shown for the first time at a show AFRMA, already in the next show on 19.05.1984 won a Siam Rat the prize for Best in Show (Sumi Mary Macdonald).


Russian Blue Point Siam

The standard of Siam- and Himalayan rat

and in this / Himalaya is a Shade (Shades), which can theoretically occur in any color. However, attempts, to draw so-called Flame Point Siamese-based Topaz, so far been unsuccessful, since the points are so diluted, that the animals appear like Pink Eyed White.

The standard of Siam Rat

The AFRMA 2)AFRMA (2017).AFRMA Official Color Standards Book Rat. describes the body color as the mean Beige, which is gradually and evenly shaded over the saddle and lower back up to the belly. Darkest color at the base of the tail should be. White or light marks on the body, feet or tail are not allowed. The abdomen should be light beige. The points will be dark sepia at Seal Point Siamese from and smoothly into the body color. At Blue Point Siamese based on Russian Blue, the body should be elfenbeifarben with a uniform blue shading over the saddle and the rear part. The points will be of a medium slate gray. The standard of NFRS corresponds to the extensive. In the German standard of color rat is given as a reason Ivory. "Discontinued to head- and tail and runs, the color changes to a dark chocolate brown. The chocolate brown should ideally by the end of the hip, facial, in the middle between the front and ear, be clearly visible on your feet no later than the end of the ankle. Points must be vorhabnden on all four legs without much white to toe. The ears should also have this dark coloring. " 3)Noack, J.S., & Flechsig, S. (2012). The German standard of color rat. Friedrich Born-Verlag.

The standard of the Himalayan Rat

Simply put, a Himalayan rat optically corresponds to a Siamese rat with less pronounced Points. the AFRMA4)AFRMA (2017).AFRMA Official Color Standards Book Rat. Or According to the body color should be white, expel without spot. The points will be of a dark sepia tone. They should not extend further than: 1. In the face: not on the eyes, 2. The ears: not below the base, 3. On the front legs: not on the elbow, 4. On the hind legs: not on the ankles, 5. the tail: no more than halfway up the fuselage, 6. On the feet: uniform color with no white in. This also corresponds to the description of the NFRS5) In the German Stasndard the color Rat6)Noack, J.S., & Flechsig, S. (2012). The German standard of color rat. Friedrich Born-Verlag is the standard for Seal Point Himalayan the for Seal Point Siamese.






The characteristic staining of Siamratte is caused by a mechanism, the acromelanism or Kälteschwärzung called. Here, the cooler body parts of animals color, he knows z.B. face, Legs and tail, dark in an otherwise bright body. This is a partial albinism, oculocutaneous albinism type specifically a 1, and not a form of melanism, as the name suggests, by a heat-sensitive tyrosinase less or no pigment is formed on the warmer parts of the body.

The genetics of Siam - and Himalayan rat

the allele, that the Siamfärbung triggers, is located on the so-called C-Locus. The abbreviation "C" stands for Colouration gene and the same gene locus is e.g.. also for them Siamfärbung and Siam- and Thai cats responsible. In some places it is also reported, that the designation C-locus stems from, that here the allele for Chinchilla staining is, but this is not the case. We now know, that for two other loci are responsible. The Siam- or. Himalaya coloration-causing allele is c(h) (For Colouration gene type Himalayas) designated.

Kuramoto et al. showed in an extensive study of pet rats mutations in 20107)Kuramoto T1, Yokoe M, Yagasaki K, Kawaguchi T, The mafuji K, Serikawa T. (2010), Genetic analyses of fancy rat-derived mutations, Exp Anim. 2010;59(2):147-55, that the Siamese-Mutation on chromosome 1 section 140.6-145.5 lies, the candidate gene is the tyrosinase gene Tyr.

On the C locus alleles can be the following:

  • C - Non-Albino bzw. Wild form (dominant)
  • c – Albinismus, Albino (recessive to C, intermediately in c(h))
  • c(h) - Akromelanismus, Himalaya (recessive to C, intermediately in c)
  • c(m) - Marten or. Devil, more on this in the article "The inheritance of the Devil-(Marten-)Allels

When considering C, c and c(h) results in the following combinations with the corresponding phenotypes:

  • C- (also CC, Cc, Cc(h))- Non-Albino, Wild form
  • cc - Albino
  • cc(h) – Himalaya
  • c(h)c(h) – Siam

With a Seal Point Siamese rat the non-agouti are(Black)-Allele on the a-locus and the Himalaya allele at the c-locus before each homozygous, further dilutions are not present. therefore it has the genetic code aa B- M- D- Rb- M- c(h)c(h) P- R- etc. Blue Point Siamese applies analogously aa B- M- D- rbrb M- c(h)c(h) P- R- etc. The same applies for aa Himalaya B- M- D- Rb- M- cc(h) P- R- etc. or. aa B- M- D- rbrb M- cc(h) P- R- etc. The basic eye color in albinos, Siamese and Himalayan Pink is. In addition, the UK black eyed allele can provide in a homozygous form for, that nevertheless dye is formed in the eyes and making them appear black.


Seal Point Siam

The breeding of Siam rats

In breeding of Siam rats the challenge to one is, to achieve as dark as possible Points, to get to the other is as complete as possible dark colored feet without white spots or toes. It is recommended, repeatedly introgress excellent Black elf and work with black-based albinos.

Black Eyed Seal Point Siam

The exhibition of Siam rats

For a show's apparently mainly males, the stronger Points trained as a female. It is also recommended, to keep the animals cool as possible before the exhibition, as low temperatures favor the formation of Points.

Black Eyed Seal Point Siam


In the history of Siamese breed has always been of particularly high importance, to obtain animals, have no white markings. Of course, however, some breeders have their Siam or. Himalayas with the drawn animals such as e.g.. Berkshires or Variegated mated. Products resulting on animals are sometimes offered under the fancy names Triamesen.

References   [ + ]

1. R. MOUTIER, K. TOYAMA & M. F. CHARRIER (1973) , Himalayan allele at the albino locus in the Norway rat, Journal of Heredity, Volume 64, Issue 5, 1 September 1973, Pages 303–304
2. AFRMA (2017).AFRMA Official Color Standards Book Rat.
3, 6. Noack, J.S., & Flechsig, S. (2012). The German standard of color rat. Friedrich Born-Verlag
4. AFRMA (2017).AFRMA Official Color Standards Book Rat. Or
7. Kuramoto T1, Yokoe M, Yagasaki K, Kawaguchi T, The mafuji K, Serikawa T. (2010), Genetic analyses of fancy rat-derived mutations, Exp Anim. 2010;59(2):147-55