The Rat Terrier can be considered a very colourful breed; with few colours being faulted or disallowed.

Eliminating faults/disqualifying colours are merle dogs, dogs with brindle colouration and solid dogs without significant (greater than 1 inch) white markings.

On the a locus, Rat Terriers are found in

  • fawn (known as tan sable)

5728584177_cec5a0abd0_z Jiggs – tan sable near/broken blanket back

  • black and tan

14791963457_6c5172dc0a_kKara – black and tan irish marked with calico


k locus – dominant black (meaning to get a black dog; one of the dog’s parents must be black)14791932030_3520c17147_kMisty – black and white irish marked (probably a seal; you can see that Misty’s black is not as deep and true as Kara’s)

all 3 of these colours can be diluted on the d locus to

  • blue fawn/blue sable
  • blue and tan
  • blue

on the b locus; you find Rat Terrier coat colours being described as;

  • chocolate sable/chocolate fawn
  • chocolate and tan
  • chocolate

Rat Terriers also express the e locus, exhibiting clear red (e/e), being named

  • lemon (blue or chocolate nose)
  • apricot (black nose)
  • Lemon or apricot pups are generally born white, then mature into a pale yellow to deep yellow colouration.

Pearl or isabella are the terms used for chocolate (bb) dogs diluted on the d locus (bb/dd).
Some black Rat Terriers do not appear deep black; more of an off-black colour; this is known as seal; and is fairly common in the breed.

Since the Rat Terrier is always considered a bi-colour breed; it would be repetitive to label a dog as _(colour)__ & white; however that is very common terminology.

Tri-colour is a black and tan dog (or blue and tan/chocolate and tan) with white markings.

White markings are generally distributed in three variations.

  • Irish markings (also referred to as tuxedo) – white socks, white underbelly, white flash on the chest and under the neck, generally with a white collar.
  • Piebald – large irregular broken white patches (to differentiate a dog’s description; sometimes the terms “saddle back” (solid colour in a saddle shape on the back) “broken saddle back” (near saddle shape of colour broken with a white marking) “blanket back” (solid colour from the withers to the tail) “broken blanket back” (solid colour from the withers to the tail broken with a white marking) will be used
  • High-piebald, near white – a dog whose predominate colour is white, with coloured markings (genetically an extreme piebald, but described in reverse).

Other terminology you might hear; includes the term calico, which is a form of creeping tan markings that occur on black and tan/blue and tan/chocolate and tan dogs.