The Border Collie a dog of many colours - Genetics

Border collies are frequently thought of as just being black and white, however this is actually far from the truth. Border Collies come in a multitude of different colours and whilst black and white represents the most commonly seen colour combination, a black and white border collie can carry the genetic ingredients for a variety of colours. So just because you may have a black and white Border collie, this does not mean that they will produce just black and white puppies.

It’s worth noting that for the serious Border collie breeder the colour of the breed is of little importance. They are more concerned with breeding to obtain the correct temperament, right character and good health than they are the colour of the animal.

Any living animal and even humans for that matter inherit many characteristics from their parents. These inherited characteristics are controlled by genes.

Offspring inherit genes from both their father and their mother in equal measure. For each genetically controlled characteristic a dog will carry two genes, one passed down from their father and one passed down from their mother. Likewise the father and mother will each carry two genes for each genetic characteristic inherited from their own parents. Although dogs carry two genes for each inherited characteristic, only one gene for each characteristic is passed on from their father and only one gene is passed on from their mother, this is how we get diversity.

Each gene has a dominant and recessive form, so for example a dog may inherit the gene for solid black coat colour from his father and the gene for solid red coat colour from his mother. Because the gene for solid black is dominant and the gene for solid red is recessive the solid black gene will mask out the solid red gene and the dog will be black and white in colour. When the dog produces offspring he will pass one gene only onto each of his puppies, some may inherit the gene for solid black coat colour whilst others the hidden recessive gene for solid red coat colour.

Genes control many characteristics such as coat colour, ear carriage, length of coat, eye colour etc... Yet a litter of four pups may vary from one another in these characteristics, one may have pricked ears, while another has low ears, one a long coat while one a smooth coat. One of the most interesting aspects of inheritance in the Border Collie breed is coat colour. One litter may contain for example; a black and white, a red merle, a red, and a blue and tan (blue tri) puppy.

The Border Collies hair follicles are made up of cells containing two colour pigments, eumelanin (black) and phaeomelanin (true red); so basically eumelanin is the pigment that produces the darker black and brown shades, phaeomelanin produces the true red. There are a vast number of genes that control the creation of these pigments within the cells and therefore control coat colour, each with a dominant and a recessive form.

The table below shows the four main genes involved in determining coat colour in the Border Collie breed and defines the dominant and recessive form of each gene.
 
Genes         Dominant              Recessive

Gene 1           Solid Black          Solid Red
Gene 2           No Tri (no tan)      Tri (tan)
Gene 3           No Dilute              Dilute
Gene 4           Merle                   No Merle

Below are some examples of how this works.

Black and white

The colour most often encountered in a Border Collie and to many people the true border collie colour. The Border Collie is in fact a white dog with patches of solid colour sometimes broken by the merle or diluted gene. The solid colour is referred to genetically as "spotting" the classic Border Collie markings are referred to as "Irish Spotting".

Black is the dominant gene for solid coat colour so a black and white dog may be masking a recessive gene, it is not possible to tell by looking at a dog what recessive genes they are carrying, if they are carrying a dominant gene that would mask the recessive genes.

Tricolour (black white and tan) Border Collies

The tricolour markings show typically as tan spots above each eye, and around the face, the top of the front legs and the lower coloured part of the back legs. Dogs showing tricolour characteristics must carry two recessive tri (tri switched on) genes.

This dog has one dominant black gene for solid coat colour (another gene for solid coat colour unknown, either black or red) and two recessive genes for tricolour switched on, hence the tricolour markings. Tri colour varies in its intensity from dog to dog.

Red (brown or liver) Border Collies

The red gene for solid coat colour is recessive to the black gene for solid coat colour, so in order for a dog to appear red the dog must carry two recessive forms of the gene for solid coat colour (i.e. red). This means that both the dog’s father and the dog’s mother must each carry at least one copy of the red recessive gene for solid coat colour.

The colour referred to as red in Border Collies is the same colour genetically as that referred to as brown or liver in some other breeds. Red is prone to bleaching in the sun and red dogs tend to have light coloured eyes and liver coloured noses.

Blue (slate) Border Collies

The blue colour is the result of the dilute gene. The two forms of the gene are no dilute (dominant) and dilute (recessive). Dilute is not a colour but acts to reduce the strength of a solid colour (either black or red) evenly across the dog’s coat. This is not the same as a blue merle - the merle gene is quite different.

In order to show a blue coat colour a dog must carry two recessive dilute genes - one from each of their parents so, either their parents must have been solid black or solid red and carried the dilute gene or been blue or lilac (dilute red) themselves.

Blue Tricolour Border Collies

Because the coat colour of the Border Collie is determined by a number of genes all independent of each other several colours may manifest themselves in one dog. Here the dog is basically a black and white who also carry’s two recessive genes for dilute and two recessive genes for tri colour (black and tan). The dog might carry one gene for solid red but we cannot tell.

In the case of this dog we know it has two recessive dilute genes or it could not show dilute blue or lilac and two dilute genes for tri or it would not show tan , we also know that it does not carry merle as merle is a dominant gene and it would show.

Red Tricolour Border Collies

Here the Border Collie is both red and white so it must carry two recessive genes for solid coat colour, black is dominant, red is recessive, and two recessive genes for tri colour, black and tan. As with the blue tricolour, the black and white and the red and white, we know that this dog does not carry merle. If merle is present it will show because it is dominant.

What we cannot tell by looking at this dog is whether or not it carry’s the dilute gene. The dog does not carry two dilute genes or it would be a lilac tri and because the dog has a solid red coat colour. But it could carry one dilute gene and one no dilute gene, the no dilute being dominant.

Blue Merle Border Collies

Merle is an interesting gene found in many breeds of dog including shelties and rough collies but often referred to by different names like dappled in Dachshunds, Harlequin in Great Danes or tweed in Australian Shepherds and so on. The merle gene is dominant so that if a dog carry’s just one merle gene he will display merle characteristics.

Merle acts to break up the solid colour of the dog's coat whether it is black or red. It does so with a patchwork of white and irregular spots or patches of black or red, depending upon whether the dog carries the dominant black or recessive red gene for solid coat colour.

Red Merle Border Collies

Because merle is dominant it might be expected that it would be very common, but this is actually not the case. Merle is what is known as a semi-lethal gene and a merle dog should never be mated to another merle. If this is the case those puppies which receive two merle genes, one from each parent are likely to suffer severe health problems.

Puppies which carry two merle genes are likely to have a completely white coat, be blind or have abnormally small or possibly no eyes at all. They may well also be partially or completely deaf. So merles must always be mated to a solid colour (whether dilute or not).

Blue Merle and Tri Border Collies

Merle is one of the few dominant genes where it is possible to determine that the dog also carries a recessive gene for no merle because of the absence of the health problems described above. Merles sometimes produce blue eyes.

The most usual form of merle is Blue merle. Here the dog carry’s the dominant black gene for solid coat colour which is turned to a marbled blue by the dominant merle gene. If the dog also carries two recessive genes for tri he will show the tri colour as well as the blue merle.

Red Merle and Tri Border Collies

As might be expected the red merle colour is less common because red is a recessive gene. Here the dog carry’s two recessive genes for the solid red coat colour and two recessive genes for the tri markings. In addition the dog carry’s one dominant gene for merle, hence the coat is marbled with white and one recessive gene for no merle. This will not cause any health problems.

Dilute blue or lilac merles are very uncommon due to the recessive nature of the dilute gene and the relative rarity of the merle gene. Most breeders would avoid such colour combinations concentrating on temperament, type and quality rather than novelty value.

Lilac Border Collies

An uncommon coat colour, seldom seen in the canine species. Lilac is the result of the recessive red gene for solid coat colour and the recessive dilute gene for diluted coat colour acting together to create a pale red silver-grey. This colour is commonly seen only in the Weimaraner breed although it can occur in Border Collies.

White Border Collies

Not a colour, but an absence of colour. So called white Border Collies simply lack the "spotting" or colour from most areas of their coat. Few Border Collies are completely white but have limited areas of colour usually on their head, particularly around the eyes. A "white" Border Collie may carry any of the colours described above but white will predominate.

White Border Collies have always been unpopular in the herding world and show ring, the standard states that white should not predominate. Although no proof exists that white Border Collies are less healthy or poorer workers than well coloured specimens, it is probably unwise to mate predominately white Border Collies to other predominately white Border Collies.

In addition to the colours mentioned above other colours appear in border collies from time to time. Sable and shaded sable are less frequently encountered colours but certainly do exist in the pure bred Border Collie. Other colours such as brindle are most certainly the result of cross breeding and some other colours such as yellow are sometimes seen abroad. These colours are probably inherited from other local breeds. The standard for the breed states that a variety of colours are permissible but that white should never predominate.