Border Collie Colours
© Sue Ader
The MBCC extends grateful thanks to Sue for allowing us to publish this article.
Please click on the thumbnails to see full sized versions of the photos.
I have been asked to write a piece about how the different colours are produced.
Firstly please let me say that health, temperament and soundness should always be given priority over colour when choosing breeding stock. Having interesting colours is just the icing on the cake.
I am sure if you already have a good understanding of genetics, you will already understand the basic principles of colour inheritance, but for those of you who find all the technical jargon a bit mind blowing, I will try to explain it simply, in layman's terms, just to give you some idea, and if you want to get a deeper understanding there are plenty of sites around that can explain it all a bit more in depth. There are new colour combinations popping up all the time, some of which are not even written about in detail in genetic sites and books, but I will try to explain a little about the ones that are most often seen.
First things first.
Every feature of your dog, from the length and colour of its hair, to the size of its ears, and the length of its tail is dependant on its genes. Genes always exist in pairs, and at the time of conception, the pup inherits one of each gene pair from each of its parents (otherwise the total number would keep doubling up).
Each colour, or coat pattern has its own gene pair, that is responsible for its colour, and it is possible for a dog to have the genes for a whole variety of colours. Although you may not be able to see some of the colours, they can still be carried and pop up in future generations.
Which of the gene pair it inherits from each parent in each case is random, which is why parents can produce pups of different colours in the same litter.
Genes can be dominant or recessive. A recessive gene is a mutation of a dominant gene. The colour you see will depend on whether the pup has inherited the dominant or the recessive gene from each parent. Dominant genes are normally shown in capital letters, while recessive genes are shown in small letters. It is possible for a dominant colour to produce a recessive colour, but it is not possible for a recessive colour to produce a dominant colour.
Coats can come in a whole range of colours, some are more common than others, some are more attractive than others, and they can also come in a variety of different shades, depending on the modifying genes that can also be present. These modifying genes are responsible for the size and density of the pigment granules, which is why you can get a range of, for example, brown coloured dogs, that can range from a very dark liver colour to a foxy red. They all have the same brown gene, but the density of colour is controlled by a modifying gene that gives the coat a different appearance.
Black is a dominant colour, it is normally shown as BB. Black can come in a variety of shades (remember the modifying genes?). A dog that is BB will not carry or produce any other colour.
Sometimes called liver, or chocolate or red, this is a recessive colour. It is a recessive form of black, and is normally shown as bb. (Different shades are produced by the action of the modifying genes).
Both parents have to carry the brown gene in order to produce a brown pup.
A black dog that has one copy of the brown gene (that it can pass on) would be Bb.
A brown dog, has two copies of the recessive brown gene, so can only pass on a brown gene, would be bb.
Brown dogs have inherited a copy of the recessive b gene from each parent, giving them two copies bb.
In order to produce brown, both parents have to have at least one copy of the b brown gene, and pass that copy on to the pup. Each parent has to be Bb – black carrying brown – or bb brown, it is not possible for two brown dogs to produce black pups, as brown is recessive to black.
Sometimes called slate, is produced by the effect of a gene that dilutes the base colour. If the base colour is black, the result of this gene is to produce a blue colour; if the base colour is brown, the result is a diluted brown – milky-tea colour, sometimes called lilac.
It is normally shown as dd for dilute. A dog that does not carry the gene for dilute would be shown as DD (non dilute) It is possible for any colour to be affected by the dilute gene.
As with the brown gene, both parents have to carry the dilute gene, and pass it on to the puppy, in order to produce a dilute colour. If one parent carries the colour and the other does not you will not be able to produce a diluted colour, but a proportion of the pups will carry the gene and be able to pass it on to future generations.
It is not possible to produce a non dilute (black for example) from two dilute (blue) parents.
It is possible to produce a dilute (blue) from two black parents who both carry the dilute gene, or from one black and one blue so long as the black parent has one copy of the dilute gene, but if one parent does not carry the dilute gene, you will not produce dilute pups.
Sable is a little different, it is normally shown as ay, and in its pure form it has the affect of producing a yellow coat, this is sometimes called clear sable. It is more common to see this colour in conjunction with the tri pattern (more on the tri pattern later), the tri is normally shown as at, and when you get the two together ay at.
You see the more normal – shaded sable - this is a yellow coat, where the tips of the hairs are black. There is often a dorsal stripe of more darkly shaded hair and a mask of darker shading though this can vary in individuals considerably. Some sables can be so heavily shaded that they can almost appear to be
tris, it is possible to get brown sables, where the tips of the hair and nose lip and eye pigment are brown and a dilute sable or blue sable where the hair tips and nose lip and eye pigment are blue/grey. You can also get sable merles, but because of the paleness of the coat these can be very hard to detect from normal sables.
Sable is recessive to most other colours with the exception of tris; it is dominant to tri.
So in order to produce sable, both parents have to either be carrying sable, and/or tri.
Almost any colour can produce sable, if both parents carry the sable gene, or if one parent carries, or is, sable and the other parent carries, or is tri.
It is not possible to produce sable pups from two tri parents.
ee Red sometimes called red – yellow – gold.
This is the same gene that is found in yellow Labradors and Golden Retrievers, along with a number of other breeds. It looks the same as a clear sable, and can vary from gold to pale cream. There should be no other coloured hairs in the coat, this gene has the effect of stripping the colour pigment out of the coat, a bit like if you washed your hair with peroxide most of the colour would be stripped out. It is a recessive gene and needs to be present in and passed on from both parents in order to show itself in the pup. If the original base colour is black the dog should have black nose/eye/lip pigment, and if the base colour is brown the nose/eye/lip pigment will be brown. I would imagine if the base colour is a dilute then the body colour would be very pale with pigment to match.
Colour To Colour Matings
People often ask if it is 'safe' to mate two coloured dogs together. There is no hard evidence to suspect that such a mating is going to produce any more problems than mating two black and whites together. Look at other breeds, Rough Collies, Shelties, Corgis, GSDs regularly breed sable to sable. Retrievers and Labradors breed ee dogs together, Weimaraner are all dilutes and Sussex Spaniels are all brown, to name just a few. There is no reason to suggest that the repeated mating of coloured dogs together is likely to produce problems or weaken the colour.
Coat patterns can be seen in any colour.
Merle is a coat pattern, not a colour. The gene that produces the merle pattern reduces the pigment in random areas of the coat. So a 'blue merle' is really a black and white dog that has had the pigment reduced in parts of its coat giving it the appearance of a blue/grey dog with black patches. If these random patches happen to be over the eye area you get blue or marbled eyes, or if on the nose, lips or eye rim, you get pink skin.
As merle is a pattern, not a colour, it is possible to produce it in any colour. You do however need to have one merle and one non-merle parent to produce the merle pattern. It is not possible to produce merle pups from two non merle parents.
As the pigment reduction is random, and it can also have a tremendous amount of variation in the amount of pigment reduction you see. It is possible to sometimes get phantom merles, these are genetically merle dogs that have just a tiny patch of merle hair, maybe only a few hairs, often in a place where it hardly notices, but as these individuals are genetically merle, they can still produce merle pups, with normal distribution of the merle pattern giving rise to the belief that merles have been produced from two non merle parents.
One important thing to remember with the merle gene is that it should NEVER be doubled up on. The merle gene is semi lethal - if you mate merle to merle, the gene can also affect the development of eyes, causing very small or non existent eye balls, and predominantly white pups that can be deaf and sterile. A merle should ALWAYS be mated to a solid colour, it does not matter what colour you mate it to, so long as it is not another merle, also it does not matter if the solid parent has merle dogs in its pedigree, the problems will not be carried down so long as you only have one merle parent.
Tri is also a coat pattern, and as with merle it can be produced in any colour.
In the case of tri, the gene responsible is a recessive gene. This simply means that in order for the tri pattern to show itself, it has to have two copies of the tri gene, and to have received a copy of the recessive tri gene from each of its parents.
If the pup receives two copies of the tri gene, you have a tri pup. If it receives one copy of the tri gene, and one copy of the non tri gene, you get a non tri pup that carries a single copy of the tri gene, and can pass the tri gene on to future generations.
If it receives two copies of the non tri gene then you have a non tri pup that does not carry tri and therefore can not pass it on to future generations.
White Markings - Irish Pattern
The white markings we see on our collies are also controlled by a coat pattern gene, and is called Irish pattern. It is a little complicated to explain, but is inherited in much the same way as the tri pattern, so if you breed from two parents with little or no white, you can expect less white on your pups, some dogs are described as 'white factored' meaning they carry an excessive amount of white, and so are more likely to produce pups with more than the desired mount of white on them. These dogs can normally be identified by the white on the back legs extending right up over the stifle joint, and often up over the loin, and are far more likely to produce pups that have excessive white on the body, so if you want to breed from such a dog, and do not want too much white on your pups, it is wise to choose a mate who does not appear to be white factored. Merles are often (though not always) white factored.
I hope this gives you a little insight into how the different colours are produced, and if you find the subject as interesting as I do I hope it will encourage you to delve deeper into the more extensive articles that can be found on colour genetics to obtain an even better understanding of the subject.