Fox Terrier Hereditary Health And Genetic Diversity

The fox terrier breed can be found in either a smooth haired or a wire haired type, and while the two coat variants mean that they are classed as two separate breeds, other than this, the two variants are essentially the same. First bred in the 19th century from descendants of an earlier variety of British terrier, the fox terrier is a close relative of various other terrier breeds, and was also formative in the establishment of some other separate breeds, including the Jack Russell terrier.

Both the wire haired and smooth haired types are mainly white in colour, with coloured markings. The fox terrier stands up to 15.5” tall at the withers, and can weigh up to 19lb, making them a small breed of dog, but not one of the tiniest.

While the fox terrier breed as a whole is more common within America than within the UK these days, the wire haired variant is much more common in the UK than the smooth. The smooth variant is actually classed as one of the vulnerable native breeds by the UK Kennel Club, which means that less than 300 new puppies of the smooth haired variant are registered with The Kennel Club each year.

In terms of the health of the fox terrier, both variants tend to be affected by the same recurrent conditions, although there are some variations. If you are considering buying either a wirehaired or a smooth fox terrier, it is of course important to find out more about their general health and hereditary wellness before committing to a purchase. We will look at these factors in more detail in this article.

Fox terrier average longevity

The median lifespan of the fox terrier is 13.2 years, but the average lifespan can range as high as 15 years, indicating that the fox terrier is overall a robust and healthy breed. The leading cause of death across the breed as a whole is old age, with the second most common cause of death being various different types of cancers.

Genetic diversity

The coefficient of inbreeding statistic for the wirehaired fox terrier is 12.4%, and for the smooth haired variety, 7.2%. This indicates that the wirehaired variant particularly is subject to a reasonable amount of inbreeding in order to keep the breed viable, and breeders should seek to reduce the percentage where possible within their own breed lines. The ideal coefficient of inbreeding statistic for a pedigree dog is 6.25% or lower.

Hereditary health tests for the fox terrier

The fox terrier overall is considered to be a fit, healthy and hardy little dog, whose conformation does not make them prone to any particular health problems. However, one condition that has been identified as a particular problem for wirehaired fox terriers is degenerative myelopathy, a condition of the spinal cord that leads to paralysis or weakness in the hindquarters. DNA testing can identify a predisposition to this condition, and breeders are advised to get their dogs tested for this condition prior to breeding them.

Other health issues

Both the smooth and the wirehaired fox terrier are also known to have a slightly elevated propensity to developing a few other health conditions as well. Some of these have a hereditary factor to them, but they are not currently conditions for which pre-breeding screening is available or offered. Some of these conditions that affect both the wirehaired and smooth haired fox terrier equally include:

• Atopy, or a hypersensitivity to certain protein particles, including pollen. This allergy causes intense itching of the skin, and can lead to sore spots and the possibility of infection due to the dog’s obsessive scratching.


• Eye problems, including glaucoma and cataracts. However, both of these conditions are generally operable.


• Myasthenia gravis, which is a neurological disorder that causes generalised weakness of the body, lethargy and an unwillingness to move far.


• Wolman disease, which is a condition that affects the body’s lipid storage.


• Various cardiac problems, including pulmonic stenosis, a heart disease that causes narrowing of the pulmonary artery.

Conditions that are known to occur within the smooth haired fox terrier breed pool with a reasonable rate of occurrence, but which are not present in any great degree within wirehaired fox terriers are:

• Myelopathy and ataxia, a condition that leads to a gradual degeneration of the body’s muscles, and associated weakness.


• Patellar luxation, a condition in which the kneecaps of the legs are not properly secured by muscles and ligaments, which can lead to dislocations.

Conditions that are found within the wirehaired fox terrier breed pool but that do not present a common problem for smooth haired fox terriers include:

• Haemophilia B, a disorder of the platelets of the red blood cells, which leads to problems with clotting.


• Epilepsy, which can usually be managed with medication. However, epileptic dogs should not be used for breeding.


• Various different types of cancers, most specifically of the bladder and the adrenal gland.