Colori del Collie
Dealing with the various colors of collies on a scientific basis, one gains highly interesting insights.
Sable & Tricolor
Let us start with the fact that from a scientific perspective only two colors exist for the collie, Sable and Tricolor. Sable is a brown shade, ranging from light gold to dark mahogany, depending on the shading.
(photo: Claudia Gebhard)
Tricolor is equivalent to the black shade, sporadically framed by red brown tan markings, especially on the cheeks, as a small patch above each eye, sometimes on the chest, on the tail and most commonly on parts of the legs.
(foto: Angelika Hofmann)
The brown color of the Sable and the black color of the Tricolor stretches from the forehead, over the ears (mostly interrupted by the white collar), over the complete back to the start of the tail and the extremities. This brown and black color is determined by eumelanin, whereas the tan markings are determined by pheomelanin. Color defining cells called melanocytes provide their color (contained in so-called melanosomes) to the hair follicles of the growing fur. These cells originally derive from the neural crest. During the embryonic phase the progenitor cells (melanoblasts) wander into the skin (epidermis). It is interesting that these cells do not only exist in the skin, but as well e.g. in the oral mucosa, even in the heart and in one of the cerebral membranes. Additionally, they also exist in the inner ear and in the iris of the eye.
How come that some collies are Sable and others Tricolor? From biology classes we know that each cell as well as each egg cell contains all necessary genetic information to be able to form a new organism once both cells have merged (fertilization). The genetic information differs in each egg and sperm, depending on the possible genes of the parents that are available. Which particular egg and sperm cell merge is coincidence. This explains why each individual has a very distinct appearance. It is well known that each ovum and each spermatozoon contains only half of the set of chromosomes of genetic information (DNA). Only after fertilization, when both sets have attached correctly to each other, new life can be formed. Each part of the chromosome - called gene – comprises of two alleles, one from the mother and one from the father.
Pure Sables e.g. have received a Sable allele from each parent. If both alleles are identical it is also called homozygous Sable. It does exist in various shades, from light gold (Gold Sable) to intense brown. These collies can only pass on Sable alleles. They never can have Tricolor offspring as they don’t possess Tricolor alleles, in contrary to Dark Sables. But if a Sable allele should encounter a Tricolor allele this results in a Dark Sable to be born (see below).
Pure Sable (Gold Sable):
(foto: Claudia Becker)
|Pure Sable||100% Pure Sable|
|Dark Sable||50% Pure Sable + 50% Dark Sable|
|Tricolor||100% Dark Sable|
Tricolors received a Tricolor allele from both parents, which means they are homozygous Tricolors. Ideally they should have an intense black without any tinge of red. Furthermore they should have the above mentioned tan markings. They only can pass on Tricolor alleles. However, if such a Tricolor allele encounters a Sable allele it results in a Dark Sable to be born as Sable dominates the color Tricolor (see also Dark Sable). Tricolors can only be born if a Tricolor allele encounters another Tricolor allele (because of the recessive inheritance, see also Dark Sable). It is indifferent whether it descends from a Tricolor or another Dark Sable.
(foto: Catherine Brisedou)
|Pure Sable||100% Dark Sable|
|Dark Sable||50% Dark Sable + 50% Tricolor|
But what happens if a Sable allele encounters a Tricolor allele? Today it is well known that Sable “dominates” over Tricolor or to phrase it the other way round Tricolor is “suppressed” by Sable, because the puppy deriving from this mating is Sable colored. Scientifically phrased, Sable possesses a dominant and Tricolor a recessive inheritance. With the contribution of Dr. Clark (USA) it is a fact today what many dog owners before always suspected, namely that Tricolor gene does nevertheless play a role in the coloring of these dogs. It is called incomplete penetrance because both colors prevail, the brown color well visible and the black color only indicated. The new-born puppies are of comparably dark color but become lighter and lighter in the following weeks so that they resemble Pure Sables. But with increasing age the Tricolor allele also becomes prevalent to a certain degree. In other words, the black color from the melanosomes finds its way into the hair follicles of the growing fur. Because of this, the brown color becomes increasingly darker especially on the back, even to the extent of dark mahogany. Some hair appears to be of intense black. Most of the times these dogs at birth had dark hair at the root of the tail and later on also at the longer lateral headhair where the neck starts. This means we have to correct ourselves, i.e. the inheritance of Sable is incompletely dominant and the inheritance of Tricolor is incompletely recessive. Collies with a Sable allele and a Tricolor allele or so to speak with a Sable-Tricolor gene are also called Tricolor-factored Sable, better known as Dark Sable. Because of the difference of the two alleles (Sable and Tricolor) it is also called heterozygous Sable. These dogs can pass on Sable alleles (50%) as well as Tricolor alleles (also 50%). Succeeding inheritance is described above (see Sable and Tricolor).
(foto: Beate Rosenbach)
The distinction between darker Sables and comparably light Dark Sables can often only be ensured through genetic testing, or by looking at the offspring if a Dark Sable or a Tricolor is chosen as mating partner. However, this approach is rather unreliable. A supposed Pure Sable recently sired 2 Tricolor puppies after having sired 30 puppies before. This happened all of a sudden although through the selected mating partners he actually should have sired Tricolor puppies before. This emphasizes the theory of inheritance. Mother Nature is always good for surprises when genes encounter each other and this is indicated here as well.
(foto: Jessica Velten)
|Pure Sable||50% Pure Sable + 50% Dark Sable|
|Dark Sable||25% Pure Sable + 50% Dark Sable + 25% Tricolor|
|Tricolor||50% Dark Sable + 50% Tricolor|
Regarding collies, the color white exists in the form of markings (like white collar, breast, belly, lower parts of the legs, paws, tip of the tail) as well as extensive white (piebald). The latter dogs are called White Collies or Color-Headed-White (CHW) because the head always has to be colored. Both variants of white are caused by different genes. These are summarized under the term MITF. As described above, the coloring of the fur is caused by the release of brown or black color through melanocytes (coloring cells). The color (contained in melanosomes) is provided to the hair follicles and the growing fur incorporates the pigments. MITF genes prevent the absorption of pigments. In this sense, white is not a color but rather the absence of color, or to phrase it more correctly the absence of pigments. MITF genes do not induce any other defects on the collies. This means it is completely irrelevant which MITF gene (Irish pattern or Piebald, see below) causes the apparently white areas. Or to phrase it the other way round, White Collies are just as healthy as colored collies that only possess white markings!
White / Tricolor:
(foto: Andrea Schneider)
White / Blue Merle
(Foto: Tomoko Ferraino)
White markings on collies are genetically fixated through two identical (homozygous) alleles called “Irish pattern”, like with many other herding dog breeds too. Through incomplete penetrance it can result in various characteristics as well (e.g. incomplete collar). But each collie possesses this gene by inheritance through the parents and passes on to the offspring accordingly.
That is also the reason why the sable-colored Collies in America are not simply called as "Sabel," but as "Sable & White". "White" just meants the white markings. By Tricolors there is not this supplement. For the sake of completeness, I like to mention that "Sable Merles" (described below) are included by the "Sable & White" in America. They are not explicitly mentioned in the breed standard. Therefore a dark brown eye color is preferred, even if brightness or blue colorations in Merles occur frequently. The same applies to the remaining brown patches in adulthood in rare cases by Sable Merles, it is also not desirable. Many judges consider such color variations (whether as eye color or skin color), as a disturbance of the harmonious overall appearance.
Sable & White
(foto: Yvonne Massafra)
|Parents:|| White Markings|
|White Markings||100% White Markings|
White Collies appear to the observer as white collies with a colored head and some colored “patches”. But scientifically looked at they are sable or tricolor collies (some specimens with reduced colors to Merle, see below) that display an extensive piebald white where usually brown (respectively Sable Merle, see below) or black (respectively Blue Merle, see below) is found. This means the white color reaches over the complete back part all the way down to the extremities. What happened? Similar to the Irish pattern gene that causes the white markings, the so-called Piebald gene prevents the absorption of pigments into the particular parts of the fur. Likewise incomplete penetrance can lead to diverse characteristics. The so-called “No Spots” only have a colored head and maybe a colored root of the tail, the rest of the dog is completely white. They are rather scarce and are considered as rarities by admirers. Nevertheless, collies with smaller areas on their backs that are excluded from piebald are actually considered desirable. These patches show pigmentation in the original color Sable or Tricolor (or their brightened colors like Sable Merle or Blue Merle see below). The correct notation of these collies is written with a slash right after the “White” and complemented with the original color, like White/Sable or White/Tricolor, etc. Some even speak of factored colors, for example a White/Tricolor is a White tricolor-factored Collie.
White / Sable:
(foto: Dr. Mirjam Kessler)
White / Dark Sable:
(foto: Beate Rosenbach)
White / Tricolor:
(foto: Kerstin Laslo)
White / Sable Merle:
(foto: Andrea Schneider)
White / Blue Merle:
(foto: Brenda Hoogstede)
Even so, the distinct white coloring depends on both Piebald alleles (this is also called white factor)to be identical, i.e. homozygous. One speaks of so-called white-factored collies if it exists only heterozygous, i.e. only one allele possesses the Piebald white but not the other. The color of these collies is normal with the exception of white areas enlarging the markings. Often not only the lower parts but also the upper parts of the extremities are white, especially at the inner thighs. The collar often appears to be bigger as well just like the white portion on belly and breast. But as an incomplete penetrance does exist likewise, the white-factor can only be presumed but not guaranteed for sure. The other way round, there are collies that no one would assume to possess a white-factor just from the looks (phenotype) but who possess it nevertheless. Hence, every once in a while it comes to surprises after the mating, because white-factored collies passes on the white-factor with a probability of 50%. If this encounters another white-factor, the puppy will be a White Collie. If it does not encounter another white-factor, the puppy will only be white-factored. White Collies however passes on the white-factor at a 100% with the same consequences as if encountered another white-factored. White is inherited completely independently of Sable and Tricolor (as well as Sable Merle and Blue Merle), similar to Merle (see below).
White / Tricolor:
(foto: Angelika Vossel)
Piebald is not genetically fixated in contrast to Irish pattern. It is highly undesired according to the British breeding standards and white collies – at least in Germany – do not get an approval for breeding. Breeders specifically have to take care not to mate white-factored dogs with one another. This even goes as far as to the fact that white-factored collies are even not desired. Matters are completely different in America where the White Collie is a quite normal and desired color variant, even though it is less common than Sable and Tricolor. In Europe, White Collies are still mistaken for the Double Merles that arise out of the mating of two Merles. Reason for this is ignorance, sometimes combined with deliberate misinformation. They too have extensive white parts, but for genetically complete different reasons and in a particularly distinct way so that even their heads are completely or partially white. This often is combined with hearing and vision disabilities right up to deafness and blindness. Further details see below. White Collies always have a colored head and they are completely healthy!
|Colored with white-factor||50% White + 50% Colored with white-factor|
|Colored (no white-factor)||100% Colored with white-factor|
|Parents:|| Colored with white-factor|
|White||50% White + 50% Colored with white-factor|
|Colored with white-factor||25% White + 50% Colored with white-factor + 25% Colored (no white-factor)|
|Colored (no white-factor)||50% Colored with white-factor + 50% Colored (no white-factor)|
|Parents:|| Colored no white-factor|
|White||100% Farbig with white-factor|
|Colored with white-factor||50% Colored with white-factor + 50% Colored (no white-factor)|
|Colored (no white-factor)||100% Farbig (no white-factor)|
The two colors Sable and Tricolor not only exist as the usual bold type, but also in a brightened style, sometimes with a pattern. Such color effects are caused by a brightening gene commonly known as “Merle”. Thus, Merle is not a distinct color, but rather a brightening. On the contrary, it even prevents an extensive bold pigmentation, i.e. coloring of the fur and causes at the same time a kind of pattern. Affected are only the colors that are determined by eumelanin. Thus, the black color of Tricolors except some small patches (bigger patches are undesired) brightens to a light silver blue color (dark steel gray is undesired) whereas the red brown tan markings (phaeomelanine) remain completely untouched by this. These collies are called “Blue Merles”. As for the Sable, the brown (eumelanine) brightens as well and these are called “Sable Merles”. The Merle gene is inherited incompletely dominant. This means that the particular dogs are not completely silver blue or light brown, but also have remaining patches of the original color. In the fur of the Blue Merle one can still see black patches that will remain for lifetime. This is different for Sable Merles where the patches can often be seen only on young puppies. Later on these patches vanish in most cases so it cannot easily be distinguished between a grown up Sable Merle and a Sable. Sable Merle offspring of Pure Sables very often resembles Gold Sables when grown up. Sable Merle offspring of Dark Sables can become very light, but they can also have a very bold - sometimes even red brown - color.
(Foto: Carina Leven)
Dr. Leigh Anne Clark (USA) discovered that the part of the genes responsible for the coloration (melanin incorporation) called “SILV” is supplemented with a further piece of DNA (called SINE) in Merles through mutation. This piece of DNA is able to reproduce and insert itself. During reproduction it sometimes comes to variances on the attached segment A (A-tail). The shorter this segment is the less brightening effect it has, up to no effect at all. If the Merle is without any brightening effect throughout the complete color range, it is called cryptic Merle (for more details see below). But usually only small areas are affected, more precisely single tufts of fur that regain their natural color (Tricolor or Sable) through another mutation. This displays in the black (Blue Merle) or brown patches (Sable Merle). The longer the segment A is the stronger is the brightening effect it has. Thus, every collie develops a very individual pattern.
All this not only affects the fur, but the color of the eyes also can be brightened. One cannot manipulate this through choice of mating partners; it is pure coincidence, like the pattern of the fur. There are collies with brown eyes (especially desired in combination with Sable Merle), some are brightened, but there are also collies with a blue spot or patch and some even with completely blue eyes. Some collies only have one brightened eye, other have variances on both eyes.
Above described variances refer to heterozygous Merles with only one affected allele. Homozygous Merles with two affected alleles have severe health damages (see below). They are called Double Merles or White Tiger and breeding is forbidden by animal protection law in Germany. They only can occur through mating of two Merles and this must never happen! Breeding with heterozygous Merles is permitted. These passes on Merle affected alleles and Merle free alleles, both with a probability of 50%. This always must be kept in mind! With every breeding with a Merle, the Merle factor is passed on and must never encounter another Merle factor from another dog to be able to exclude the danger of generating Double Merles at 100%. Therefore breeding of Merles fundamentally should only be done by competent and responsible breeders! Merle is inherited completely independent from Sable, Tricolor and White.
(Foto: Martina Becker)
(foto: Andrea Schneider)
(foto: Andrea Schneider)
Inheritance (forbidden combinations are listed only for better understanding; they never must be realized!):
|Parents:||Merle (heterozygous) (permitted)|
|Merle-free||50% Merle-free + 50% Merle (heterozygous) (permitted)|
|Merle (heterozygous) (permitted)|| 25% Merle-free + 50% Merles (heterozygous) + 25% Double Merle (forbidden!)*|
|Double Merle (forbidden!)*||50% Double Merle (forbidden!)* + 50% Merles (heterozygous)|
|Merle (heterozygous) (permitted)||50% Merle-free + 50% Merles (heterozygous) (permitted)|
|Double Merle (forbidden!)*||100% Merles (heterozygous)|
*Mating of Double Merles of course is forbidden because generating Double Merles is forbidden (at least in Germany) and therefore they are not permitted for breeding. For completeness sake this is listed here as breeding unfortunately is not forbidden in America and many other countries.
Collies possessing cryptic Merle are collies that look like completely normal Sable or Tricolor (phenotype). Some have small spots of Merle that are so minor that they can easily be overlooked. Others do not show any brightening at all. But genetically they are all carriers of the Merle gene. How can that be? To describe this we need to go back to the scientific part. Let us recall the inserted piece of DNA SINE and the possible variety in length of the segment A. Regarding cryptic Merle, the segment A (A-tail) everywhere is so short that it causes no brightening or to a very small extent. This is why these dogs look like normal colored Sables or Tricolors. This admittedly rare but consistently appearing phenomenon is also known among White Collies.
The inheritance is the same as with the well visible Merle (see above). If a cryptic Merle would be mated to another Merle (no matter whether cryptic or not) it would lead to Double Merles whose breeding is forbidden by animal protection laws (see below for details). This must be prevented by all means! This is why it is mandatory for the offspring of a Merle to be genetically tested (M-Lokus) if mating with another Merle is planned and it cannot be surely excluded that the first one may be a carrier for Merle!!! This is defined accordingly in our breeding regulations.
Inheritance: (see tables under Merle).
Normal Merles as well as cryptic Merles are just as healthy as Merle-free dogs. They are also called heterozygous carriers of a Merle allele as they possess an affected gene as well as an unaffected gene. Things are different if one breeds with two dogs that both carry the Merle factor. The risk of inexperienced mating is particularly high in the case when collies are cryptic Merles or genetically not annotated Sable Merles because it is not obvious that they are carrier of the Merle gene. Mating two Merles has a 25% probability for generating so-called Double Merles, or White Tigers. They are homozygous carriers of the Merle gene, both from mother and father. They usually have extensive white parts also in the area of the head. This is in contrary to the White Collie that is also called Color Headed White (CHW) and always possesses a colored head. Many of the Double Merles show hearing and vision disabilities, many are blind and/or deaf. The latter moreover causes problems with the sense of balance, also e.g. when swimming. Because of these quite often massive health disabilities this mating is forbidden in many countries, e.g. in Germany, although these dogs can be considered completely healthy in other respects. In America they are “not recommended”, but are currently not entirely forbidden.
What is it that leads to these problems? Pigment producing cells (melanocytes) not only occur as part of the creation of the fur that is visible from outside, but also in other tissues, e.g. in the choroid, the iris of the eye and in the inner ear. Originally all of them were developed in the neural crest of the embryo, which also explains the variety of occurring problems. Regarding the Double Merle, the pigment-less precursor cell (melanoblasts) in many areas are not developed into fully functional pigment-producing cells (melanocytes) with above mentioned damages as a consequence.
This is why it is essential to prevent mating of two Merles in any case. Fortunately a genetic test is available today to discover cryptic Merles. This test should absolutely be used to securely prevent such risks (see our breeding standards). Reputable breeding associations register the color Sable Merle in the pedigree to prevent the risk of mating them with other Merles. Should it be unclear in the case of a Sable with a Merle parent that it indeed could be a Sable Merle, genetic testing should be conducted in any case to be on the safe side before mating the dog with a Merle.
Double Merle (most of them show severe hearing and vision disabilities - therefor they are forbidden in Germany and some other countries!):
Inheritance: (see tables under Merle).
At first sight Harlequins resemble Blue Merles; however, big areas of the silver blue part of the fur are even brighter, often being large white areas. The otherwise common black spots are frequently missing within these bright areas. Instead comparably large black patches are developed. The head usually is colored and the tan markings often are developed normally. This is according to later knowledge of Dr. Clark (USA) another Merle variant too, or to be more precise another pattern variant. The dogs are only carrier of one Merle allele (heterozygous Merles) in contrary to Double Merles and additionally show another mutation, either on or very near to the Merle gene. Unfortunately the exact part of the genes has not been discovered yet. But it is known that it is not identical to the one of the Great Danes. Besides, in Finland collies show a further variant that is not identical to the “common” Harlequins in America and the rest of Europe. If Sable Merles show this color pattern variant among Great Danes they are called Fawnlequins. Some people assign this expression also to collies if they originally are Sable Merles. Dr. Clark assures that the Harlequin gene does not cause any defect and thus does not lead to health disabilities!
Harlequins are rather scarce. But the Harlequin gene presumably is rather widespread because single cases occur at different breeders, some of them well noted. Harlequin becomes externally visible only if it encounters a Merle gene. On the contrary Sable and Tricolors only appear to be possible carriers. That way it could spread further unnoticed, virtually as a “stowaway”. But among the littermates “normal” Merles can be found that are genetically free of the Harlequin gene (Non-Harlequins).
(foto: Catherine Brisedou)
The colors of this Collies appear diluted. The pheomelanin-colored areas appear grayish and the eumelanin-colored areas (red brown tan markings) appear creamy. with this color-variant have a grey fur. All parts of coat, which are colored by pheomelanin are diluted by a further mutation at the Merle-gene, so that they coat appears grey. The eumelanin-colored areas (red brown tan markings) are not affected, as well as The White Markings (collar, etc.) appear normally. Affected dogs carry all, according to recent findings by Dr. Clark (USA), a single Merle allele is heterozygous (Merle), which has got a further mutation. Genetically seems to be again the A-segment (A-tail) affected (see above Merle and Cryptic Merle). Dr. Clark is planning detailed research on this.
Not affected Blue Merle littermates do not have a higher risk to pass on Maltese Grey to their offspring. Maltese Grey collies do not have health disability because of this extraordinary color development, Dr. Clark assures! However, they can just have Maltese Grey as offspring and not "normal" Blue Merles, if they are mated to a Tricolor. A few years ago, Dr. Clark has examined a bitch, an obvious regular Blue Merle, after she has born a Maltese Grey puppies born. She found in her coat just one very small piece, where the fur was diluted. So it seems that here also the inheritance is also of incomplete penetrance.
Maltese Grey is very scarce. It is assumed that many newborn puppies with a distinct grey fur were euthanized in the past because the people were afraid that the dogs might be sick. The Maltese Grey gene also becomes externally visible only if it encounters a Merle gene. One can even detect it genetically by the "D-locus". The causative gene is called Dilution gene (color dilution gene). It must not to be confused with the brightening-gene by Merles (M-locus). It is, as well as the tri-gene, a recessive gene. This means both parents have had to passes it on (homozygous), because otherwise the affected allele would be overlaid by an unaffected. This explains also why this color is hardly seen anywhere, because the likelihood that these rare alleles meet each other is extremely low.
Maltese Grey (also called Maltese Blue):
Maltese Grey must not be confused with collies that are affected by Grey Collie Syndrome (GCS), also called cyclic neutropenia as every approximately 11 days a dramatic decline of leucocytes occurs. Our breeding standards prohibit the birth of these dogs, but I nevertheless want to comment on this for better understanding. These dogs have a greyish fur, but the nose is even more brighter and the tan markings are completely missing. The dogs are mostly in a very bad overall condition and very susceptible for infections. This is the reason why they usually are backward in development compared to their healthy littermates. Many do not live to adulthood as they die of ordinary infections.
Grey Collies Syndrom / Cyclic Neutropenia (severe diseases!):
Some collies possess some spots or jots that conform to their basic color (brown or black, in occurrence of Merle gene in some circumstances brightened). These spots predominantly occur on the forelegs and paws, but in rare cases they are dispatched over the complete body. Is the Collie colored, one can not see them spot because they are hidden in the normal body color (for example on the back). It is assumed that the inheritance is incompletely dominant. Because of the incomplete penetration often only individual some very very few spots are visible in the best case. The rest remains hidden.
Text sources (following the links you can find many interesting photos besides the original text):
Dr. Leigh Anne Clark (USA), Jacquelyn Evans & Dr. Allison Starr-Moss, written by Kathy V. Moll with the permission from the Collie Club of America Bulletin, Newsletter Collie Healthfoundation Summer 2014, page 12
Dr. Leigh Anne Clark (USA), Dr. Mike Vaughan, written by Kathy V. Moll, Deep River Collies, CCA Breed Education Guest Writer, page 1-8
Dr. Leigh Anne Clark, Dr. Phil Sponenberg, & Dr. Mike Vaughan, written by Kathy V. Moll, Deep River Collies, www.colliesonline.com
nm-collie rescue, at the bottom „Hershey“
collie-online, by Patrick Martin and a quote of Dr. Leigh Anne Clark: