Colors

Coat Colour in Bull Terriers 

There are a limited number of coat colours in Bull Terriers. All Bull Terriers fall into one of two groups:

There is the iconic White Bull Terrier which is either all white or may have small patches of colour, and the Coloured Bull Terrier which, while it may have some white markings, is predominantly coloured - either Brindle, Red, Black & Tan or Black Brindle.

In order to understand coat colour in Bull Terriers it is only necessary to know that there are three sets of genes causing these colour varieties. In a simplified way, they are:

1. Base Coat Colour gene (known as the Agouti- or A-Locus Series) This gene causes two options:
Red Base Coat –

This is a plain red base coat (seen in a Red dog or found under the brindle pattern of a Brindle dog). The plain red base coat can vary from light tan through to a deep red brown.

Black on Red Base Coat –

This is a black overcoat on the red base coat (seen in a Black & Tan/Tricolour dog or under the brindle pattern of a Black Brindle dog). The black overcoat on the red base coat will be referred to here as Black on Red and is essentially a black covering on the red base coat. This black covering does not fully extend over the red and the red colour can be seen on the face forming eyebrows and cheek patches, on the chest, lower legs and under the tail. The extent of red showing around the edges of the black varies in individual dogs.

2. Brindle Patterning gene (known as the K-Locus Series) This gene causes two options:
No Brindle Pattern –

This is seen in Red dogs and Black & Tan/Tricolour dogs.

Brindle Pattern –

Brindle is a pattern of black stripes on the background colour of the base coat.

The brindle pattern on the Red base coat shows as a Brindle dog and the brindle pattern on a Black on Red base coat shows as a Black Brindle dog. Variation in the shade of colour of the base coat and the width of the black stripes can result in unique brindle patterns.

3. White Masking gene (known as the S-Locus Series)
This gene controls the amount of white pattern masking the colour of the dog.

A complete white mask results in a White Bull Terrier.

It is important to realise that a White Bull Terrier has got colour (a Red or Black on Red base coat and a Brindle pattern or not) like any Coloured Bull Terrier. The white mask is simply covering it and preventing it from being visible.

A Bull Terrier with no white markings or very limited white patches without any extension over the back at all is a Solid Coloured Bull Terrier.

In Bull Terriers, a less important fourth gene (MC1R gene) is responsible for the dark facial mask known as smut marking. Up until 2007, it was believed that only Red Bull Terriers could have smut markings and that Brindle, Black Brindle and Black & Tan/Tricolour Bull Terriers did not have this at all. We now know that all Coloured Bull Terriers can have smut markings. It is only is Red Bull Terriers that the mask is easily visible. In the other Coloured and White Bull Terriers the mask is either camouflaged by dark brindle patterning, hidden by the Black on Red base coat or covered by the white mask.

The different genetic combinations produce the following coat colour options in Bull Terriers:

1) White –
These appear all white but they may have patches of colour, most likely on the head near the ears and eyes. They are, however, not really white as all White Bull Terriers carry colour and pass on colour to their offspring even though that colour may not be visible. The White expression is a ‘mask’ hiding the true genetic colour of the dog. A careful look at the hairs around the ears of an all-White Bull Terrier can help figure out what colour it is carrying.

4) Black and Tan/Tricolour –

This pattern is black with tan (red) markings on the eyebrows, cheeks, chest, lower legs and bottom. If minimal white is present, it is called a Black & Tan Solid (also known as Tricolour Solid) but if there is black and tan colouring with white markings on the face, collar, chest, underbelly, feet and tail, then it is called Black & Tan & White or, more commonly, is it simply called Tricolour (it is not a Solid).

5) Black Brindle –

This pattern is black with brindled markings on the eyebrows, cheeks, chest, lower legs and bottom. The brindle colour can be very variable. If minimal white is present, it is called a Black Brindle Solid but if there is black and brindle colouring with white markings on the face, collar, chest, underbelly, feet and tail, then it is called Black Brindle & White.

General Rules of Colour Expression in Bull Terriers:

• There are only three different genes causing colour variation in Bull Terriers.

  
  

• These genes affect:

  o the extent of white;

  o the basecoat colour and 

  o the brindling pattern.

   

• This results in nine colour variations in Bull Terriers: 

  o White

  o Brindle Solid  

  o Brindle & White

  o Red Solid

  o Red & White

  o Black & TanSolid (also known as TricolourSolid)  

  oTricolour (also known as Black&Tan & White)

  o BlackBrindleSolid

  o BlackBrindle&White

What coat colours are producing in different matings? Let us look at each gene separately first.

Inheritance of the White Mask

Any Bull Terrier will be one of three genetic options as far as the White Mask is concerned:

• White – that is the body is all white with or without coloured head markings

• Coloured & White – predominantly coloured (not white) with strong white collar crossing the back, white chest, under-body, muzzle, blaze and feet

• Solid Coloured – all Coloured with or without limited white markings on the muzzle, chest and/or feet