Health & Testing

L-2-HGA (L-2-hydroxyglutaric aciduria)

In Staffordshire Bull Terriersthis is a neurometabolic disorder characterised by elevated levels of L-2-hydroxyglutaric acid in urine, plasma and cerebrospinal fluid.

L-2-HGA affects the central nervous system, with clinical signs usually apparent between 6 months and one year (although they can appear later). Symptoms include epileptic seizures, "wobbly" gait, tremors, muscle stiffness as a result of exercise or excitement and altered behaviour.

The mutation, or change to the structure of the gene, probably occurred spontaneously in a single dog but once in the population has been inherited from generation to generation like any other gene. The disorder shows an autosomal recessive mode of inheritance: two copies of the defective gene (one inherited from each parent) have to be present for a dog to be affected by the disease. Individuals with one copy of the defective gene and one copy of the normal gene - called carriers - show no symptoms but can pass the defective gene onto their offspring. When two apparently healthy carriers are crossed, 25% (on average) of the offspring will be affected by the disease, 25% will be clear and the remaining 50% will themselves be carriers

The mutation responsible for the disease has recently been identified at the Animal Health Trust. Using the information from this research, we have developed a DNA test for the disease. This test not only diagnoses dogs affected with this disease but can also detect those dogs which are carriers, displaying no symptoms of the disease but able to produce affected pups. Carriers could not be detected by the tests previously available which involved either a blood or urine test detecting elevated levels of L-2-hydroxyglutarate or magnetic resonance imaging. Under most circumstances, there will be a much greater number of carriers than affected animals in a population. It is important to eliminate such carriers from a breeding population since they represent a hidden reservoir of the disease that can produce affected dogs at any time.

The test is available now and information on submitting samples is given below.

Breeders will be sent results identifying their dog as belonging to one of three categories:

CLEAR: the dog has 2 copies of the normal gene and will neither develop L-2-HGA, nor pass a copy of the L-2-HGA gene to any of its offspring.

CARRIER: the dog has one copy of the normal gene and one copy of the mutant gene that causes L-2-HGA. It will not develop L-2-HGA but will pass on the L-2-HGA gene to 50% (on average) of its offspring.

AFFECTED: the dog has two copies of the L-2-HGA mutation and is affected with L-2-HGA. It will develop L-2-HGA at some stage during its lifetime, assuming it lives to an appropriate age.

Carriers can still be bred to clear dogs. On average, 50% of such a litter will be clear and 50% carriers; there can be no affecteds produced from such a mating. Pups which will be used for breeding can themselves be DNA tested to determine whether they are clear or carrier.

Samples for testing (3mls blood in an EDTA tube), should be sent together with a completed DNA Testing form and a cheque for £60-00 (inc VAT) for each sample to Genetic Services, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU.

Yoy can download the appropriate form from the AHT website at http://www.aht.org.uk/

The cost for the whole service will be £60 per dog.

Information about the testing can be found at http://www.aht.org.uk

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Hereditary Cataract

In Staffordshire Bull Terriers has been recognised as an inherited condition since the late 1970's. Affected dogs develop cataracts in both eyes at an early age. The condition is not congenital, so the lenses are normal at birth but cataracts appear at a few weeks to months in age, progressing to total cataract (and resulting blindness) by 2 to 3 years of age. 

The mutation, or change to the structure of the gene, probably occurred spontaneously in a single dog but once in the population has been inherited from generation to generation like any other gene. The disorder shows an autosomal recessive mode of inheritance: two copies of the defective gene (one inherited from each parent) have to be present for a dog to be affected by the disease. Individuals with one copy of the defective gene and one copy of the normal gene - called carriers - show no symptoms but can pass the defective gene onto their offspring. When two apparently healthy carriers are crossed, 25% (on average) of the offspring will be affected by the disease, 25% will be clear and the remaining 50% will themselves be carriers

The mutation responsible for the disease has recently been identified at the Animal Health Trust. Using the information from this research, we have developed a DNA test for the disease. This test not only diagnoses dogs affected with the disease but can also detect those dogs which are carriers, displaying no symptoms of the disease but able to produce affected pups. Under most circumstances, there will be a much greater number of carriers than affected animals in a population. It is important to eliminate such carriers from a breeding population since they represent a hidden reservoir of the disease that can produce affected dogs at any time.

The test is available now and information on submitting samples is given below.

Breeders will be sent results identifying their dog as belonging to one of three categories:

CLEAR: the dog has 2 copies of the normal gene and will neither develop Hereditary Cataract, nor pass a copy of the Hereditary Cataract gene to any of its offspring.
CARRIER: the dog has one copy of the normal gene and one copy of the mutant gene that causes Hereditary Cataract. It will not develop Hereditary Cataract but will pass on the Hereditary Cataract gene to 50% (on average) of its offspring.
AFFECTED: the dog has two copies of the Hereditary Cataract mutation and is affected with Hereditary Cataract. It will develop Hereditary Cataract at some stage during its lifetime, assuming it lives to an appropriate age.

Carriers can still be bred to clear dogs. On average, 50% of such a litter will be clear and 50% carriers; there can be no affecteds produced from such a mating. Pups which will be used for breeding can themselves be DNA tested to determine whether they are clear or carrier.

Samples for Hereditary Cataract testing only can be cheek swabs (swabs will be provided free by AHT), samples for Hereditary Cataract and L-2-HGA DNA testing together must be 2mls of blood in an EDTA tube. Samples should be sent with a completed DNA Testing Form and a chequeper sample for Hereditary Cataract testing alone, per sample for Hereditary Cataract and L-2-HGA DNA testing together, to Genetic Services, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU. DNA testing forms can be downloaded from our web site ( http://www.aht.org.uk ). Blood samples which have already been tested for L-2-HGA can also be tested for Hereditary Cataracts - please provide a completed DNA Testing Form quoting the Sample Number from the L-2-HGA certificate, with a cheque inc VAT. DNA testing forms can also be obtained by contacting 08700 509144

PHPV & Testing

There are 2 forms of eye disease that Staffordshire Bull Terriers are known to suffer from these being Hereditary Cataracts (HC) & Persistent Hyper Plastic Vitreous (PHPV)

Persistent hyperplastic tunica vasculosa lentis and persistent hyperplastic primary vitreous are congenital ocular anomalies that can lead to cataract formation. A line of insertional mutant mice, TgN3261Rpw, generated at the Oak Ridge National Laboratory in a large-scale insertional mutagenesis program was found to have a low incidence (8/243; 3.29%) of multiple developmental ocular abnormalities. The ocular abnormalities include persistent hyperplastic primary vitreous, persistent hyperplastic tunica vasculosa lentis, failure of cleavage of the anterior segment, retrolental fibrovascular membrane, posterior polar cataract, and detached retina. This transgenic mouse line provides an ontogenetic model because of the high degree of similarity of this entity in humans, dogs, and mice.

Persistent hyperplastic tunica vasculosa lentis and persistent hyperplastic primary vitreous (PHTVL/PHPV) are congenital ocular anomalies that occur in dogs, humans, and a line of transgenic mice.Sequelae resulting from this anomaly include posterior subcapsular cataract, retrolental fibrovascular membrane causing leukocoria, and secondary retinal detachment.This entity has been shown to have a hereditary basis in two breeds of dogs, the Doberman Pinscher and the Staffordshire Bull Terrier, but a specific genetic basis has not been found. The morphogenesis of PHTVL/PHPV has been described previously in dogs with the use of transmission and scanning electron microscopy.

Further details can be found on The Breed Councils Pages