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Jack Russell Coat Types: 3 Hair Varieties and the Genetics

Jack Russells have one of three coat types, either smooth, rough, or broken:

  • Smooth-coated Jack Russells Terriers have short hair and a sleek appearance.
  • Rough-coated Jack Russell Terriers’ hair is 1 to 2 inches long. They look messy and are often mistaken for a separate breed.
  • Broken-coated Jack Russells are a combination of smooth and rough coat types. 

While Jack Russells have different coat types, they are not considered separate breeds. Their hair length is the only difference between the three types of Jack Russells. 

The three Jack Russell Terrier coat types do not influence the dogs’ personalities either. They always have a protective personality. 

Jack Russells also have dense undercoats that protect them from the cold during winter.

This article explores the three types of Jack Russell Coats, and how genetics influence the breed’s specific hair types.

The 3 Jack Russell Coat Types

The three types of Jack Russell Terrier coats are smooth, rough, and broken. Jackies with different coat types are not considered different breeds, even though they have different appearances. 

Jack Russells have the same characteristics, no matter their hair length or coat type. The only difference lies in the looks and genes that determine hair appearance.

The color of the coat is not influenced by the type of coat. All coat types come in various colors such as the following:

  • White
  • Tan
  • Black
  • Brown
  • Red
  • Yellow

Related: Jack Russell Colors: 7 Unique Colors and Coat Variations 

1.  Smooth-Coated Jack Russells

Smooth-Coated Jack Russells

The hair of Jack Russell Terriers with smooth coats is shorter than one inch. Their coat has the same length all over their body and is not soft, despite its name. This hair of this coat grows in one direction and provides a sleek appearance, from where it derives its name.

Smooth-coated Jack Russells are the most common type of Jakies in the United States. They are moderate to heavy shedders. Even if their hair is short, it is not soft. 

Smooth-coated Jack Russell Terriers with soft hair are not accepted in competitions. They need to have wired hair. Otherwise, they don’t meet the breed standards.

Competition Requirements

Smooth-coated Jack Russells must check the following list to fulfill breed standards:

  • The coat must be left as it is. No alterations are allowed.
  • The coat is dense, short, and flat.
  • The hair does not have a soft texture.
  • The coat should protect the dog from various weather conditions.
  • The hair does not have a wooly or silky texture.

Related: Long-haired Jack Russells

2. Rough-Coated Jack Russells

Rough-Coated Jack Russells

Rough-coated Jack Russells are also called wire-haired Jack Russells. Their hair grows in more than one direction and is coarse. They have medium-length hair growing on the legs, head, or body. Rough-coated Jack Russells often display facial furnishings such as mustaches, beards, or thick eyebrows.

Rough-coated Jack Russells look messy. Because of their wiry hair, they have elevated protection from environmental factors. This includes cold and hot weather, as well as UV rays. 

Jack Russells with rough coats are sometimes mistaken for other breeds. This happens because people think of all Jack Russells are smooth-coated.

Competition Requirements

Rough-coated Jack Russells must check the following list to fulfill breed standards:

  • The coat should be double-layered.
  • The undercoat is soft and dense.
  • The outer coat is wiry and dense.
  • The hair over the dog’s eyes takes the shape of eyebrows.
  • The hair around the muzzle forms a beard.
  • The hair is short enough not to hide the dog’s body shape.
  • The coat is not wooly or silky.

3. Broken-Coated Jack Russells

Broken-Coated Jack Russells
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Broken-coated Jack Russells have smooth hair with patches of rough hair. It is a combination of smooth and wired hair. Jack Russells with broken coats have rough hair on their heads, legs, faces, or bodies.

Jack Russell Terriers with patches of rough hair can take part in competitions. They are accepted as a variation of the breed.

Some broken-coated individuals have rough hair patches that are almost invisible, while others have large, visible patches. 

The patches are not symmetrical.

Competition Requirements

Broken-coated Jack Russells must check the following list to fulfill breed standards:

  • The is smooth and flat, with patches of wire hair.
  • Their hair is closer to the body compared to the hair of rough-coated Jackies.
  • The hair is longer than the one of smooth-coated Jack Russells.
  • Face furnishings are optional.
  • The coat is not silky or wooly. 

Do Jack Russells Have Undercoats?

Yes, Jack Russells have dense undercoats. The undercoat hairs are short and soft and serve as insulation. It protects Jack Russells from the cold in winter. In the summer, the undercoat and the outer coat keep them cool.

The two coat layers of Jack Russells have a protective role. 

The hairs of the outer coat are called guard hairs[1] and protect them from insect bites and offer UV protection. 

This allows Jack Russells to enjoy hot summers. The longer the outer layer, the more protected a Jack Russell is.

Do Jack Russells Have Undercoats

Is The Undercoat Separate from The Outer Coat?

No, the undercoat and the outer coat are not completely separated. They grow from the same hair follicles. A hair follicle produces one or two main hairs and many secondary hairs. The main hairs are guard hairs and form the overcoat. The secondary hairs form the undercoat.

Jack Russell puppies are born single-coated. As puppies, they have numerous hair follicles which produce a single silky and soft hair. 

When they reach three months, Jackies’ hair follicles begin the production of multiple hairs. 

By the age of one, Jack Russells’ coats are fully developed.

Do Jack Russells Shed Their Undercoat?

Yes, Jack Russells shed their undercoat. Shedding happens when the hair follicles end their growth cycle. Jack Russells lose their undercoat hairs because both the outer coat and the undercoat grow from the same hair follicles.

Dogs’ hair grows from hair follicles, which are small openings on the skin.

Hair grows through these openings in 3 phases:

  • The anagen phase
  • The catagen phase
  • The telogen phase

The anagen phase has a normal growth rate. 

It is followed by the catagen phase. During this phase, the hair growth slows down and becomes thinner. 

The telogen phase is when the hair completely stops growing and the hair follicles rest. 

The hair sheds when the telogen phase ends. At this point, the hair follicles restart their growth cycle.

Related: Do Jack Russells Shed?

Can You Shave a Jack Russell Terrier?

Yes, you can shave a Jack Russell Terrier, but you will do more than harm than good. If you shave a Jack Russell, the undercoat will grow first and the outer coat will grow slower. The soft undercoat will attract UV rays, keeping your dog warm.

Jack Russells’ new coats become sticky and attract grass and debris.

Groomers do not recommend shaving a double-coated dog[2]. Some owners believe it reduces shedding but this is a myth. 

Avoid this procedure, except in extreme situations such as medical interventions.

Can You Shave a Jack Russell Terrier

How Genes Influence Jack Russell Terriers’ Coat Types

Jack Russell Terriers’ coat type is influenced by length genes, wire genes, and curl genes. A study[3] determined there are three main genes that influence a dog’s hair. 

The hair genes are responsible for the appearance of dogs’ coats in 90% of the analyzed breeds.

The breeds whose hair is not influenced by these three genes are Silk Terrier, Yorkshire Terrier, and Afghan Hound.

The three genes that influence Jack Russell Terrier’s hair affect three elements:

  • Length
  • Curl
  • Arrangement[4]

This table describes the genes that influence Jack Russells’ hair type.

Gene Scientific NameDetermines Variants
L – lengthFGF2Short or long soft hair L – short coatl – long coat
R – curlKRT71Curly or straight R – curlyr – straight
W – wiredRSPO2Wiry hair with mustachesW – wiredw – non-wire

Jack Russells Phenotype

The phenotype of a Jack Russell refers to its physical characteristics. It is influenced by the combination of Jack Russells’ genes, called the genotype.

How genes influence appearance is not fully understood. But there are some mechanisms that have been explained by scientists.[5]

The table below illustrates what genes are present in various Jack Russell phenotypes.*[6]

PhenotypeL (long) – FGF5W (wired) – RSPO2R (curl) – KRT71
Short– – – 
Wire– – 
Broken – +– 

*( – ) =  the absence of genes, ( + ) the presence of genes 


Jack Russel Terriers can have three types of coats: smooth, rough, and broken. The type of hair a dog has is influenced by genes. Smooth-haired Jack Russells have short hair. Rough-coated Jack Russells display medium hair. Broken-coated Jack Russells are a combination of the two.

Jack Russells have undercoats that keep them warm during winter. They are moderate to heavy shedders and don’t need intensive grooming. They are cute and fun to be around,  regardless of their coat length. 

About Dennis Stapleton

Dennis Stapleton has a passion for animals, especially dogs, and their relatives. He’s intrigued by their social structure and loves to write and teach about the world's most popular pet animal.

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