L-2-HGA
(L-2-hydroxyglutaric aciduria) in Staffordshire Bull Terriers 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.

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.

HC
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.

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.

For more info on genetic testing or to arrange to have your stafford tested then go to the animal health trust site. http://www.aht.org.uk/

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PLEASE NOTE THAT THE AHT IS NOW ASKING FOR BLOOD SAMPLES FROM PHPV AFFECTED SBTs, THEIR SIBLINGS, PARENTS AND GRANDPARENTS TO ENABLE THEM TO PROGRESS THEIR RESEARCH

For many years now the breed has been aware of two hereditary eye conditions, HC (Hereditary Cataract) and PHPV (Persistent Hyperplastic Primary Vitroeus) You may already have seen elsewhere on the site reference to this. It is known that HC is inherited by an autosomal recessive path (i.e. that both parents must be carriers of the defective gene to produce affected offspring). HC is a progressive condition and this means that although the puppy is not born with cataracts they will start to develop at a juvenile stage (maybe from 8 months onwards) and will progress until the dog is totally blind. The condition is bi-lateral, meaning that it will affect both eyes equally.

The mode of inheritance for PHPV is not so clear, but it is known that it is a congenital condition (present at birth) and that it is not progressive. This means that if a puppy is born with PHPV it can be detected by ophthalmic screening from 6 weeks of age and if it is affected, whatever the condition of the problem at that stage it will not change throughout the dog’s life.

Either condition can be operated on but it is a serious operation, obviously quite traumatic and expensive. It is not always covered by pet insurance due to the hereditary nature. It is important that dogs are screened and either DNA tested for HC or certified ‘unaffected’ for PHPV before being bred from.

Mr S. J. Foster of the BVA eye panel has written the following on PHPV

"Two breeds are acknowledged to suffer from PHPV in the UK - the Dobermann and the Staffordshire Bull Terrier.

The appearance of the condition is somewhat different breed to breed but, in essence , is due to the same or similar pathology and same sequence of events.

The abnormality arises somewhere around the 4th to 5th week post conception, i.e. at the junction of the embryo developing into a foetus.

The fault is linked with a developmental anomaly of the blood vessel coat of the lens which is instrumental in the formation of the lens itself and the vitreous body. The vitreous body forms progressively with the passing of time as a result of this active blood supply, which must have done its job at birth. If the blood vessels are not properly disposed of the remnants are referred to as persistent primary vitreous or as hyaloid remnants. Hyaloid refers to the principal blood vessels that travel between the optic disk and the rear face of the lens. There is another web like vascular coat coming from the iris to feed and form the front part of the lens. This too may persist as a pupillary membrane which can appear as a few dots on the front capsule of the lens to more overt strands of tissue from the face of the iris to another part of the iris or even to the front capsule of the lens. This last set of changes is uncommon in the Dobermann but is still seen from time to time. There is no necessary link between this vascular remnants and PHPV.

The formation of PHPV in the Dobermann Breed is substantially variable.

It is usually bilateral (that is affecting both eyes) and can vary from a small aggregation of deposits on the rear face of the lens, specifically the lens capsule to whole sheets of residual tissue, sometimes containing blood vessels which are patent.

Although there has been a classification given for PHPV on a scale of one to six, with one being the least affected and six being the most affected, there seems little point in pursuing these graduations since there is no evidence that grade one is less heritable than grade six, although it may give a prognosis about sight and the future wellbeing of the eye.

There is some degree of argument as to whether the condition is substantially due to a primary metabolic disorder of lens fibres subsequently leading to the formation of an abnormal posterior lens capsule or whether it is the fault of the vascular coat giving rise secondarily to the lens changes.

Whatever the theory any deposit on the posterior capsule of the lens in the breed should be taken as being highly suspicious if not diagnostic of PHPV. There are minor remnants seen in all breeds from time to time related to a vestige of the hyaloid vessel system attached to the posterior lens capsule often referred to as Mittendorf's dart. This can be recognised, such that it is not confused with PHPV. It is rare to see any non-pathologic form of aggregation on the posterior capsule otherwise.

Clearly minor aggregations are unlikely to give rise to sight abnormalities, but since the majority of the more prominent remnants occupy the visual axis sight abnormalities may be slight to extreme with blindness either at the time or later, due to intraocular haemorrhage arising for those with the worst affliction.

The inheritance of PHPV in the Dobermann is by an autosomal irregular dominant with variable expression. This is the expected inheritance type due to observation of the disease pattern in affected animals in litters and their antecedents. A dominant genetic disorder is passed on to every member of an animal's progeny, but due to the irregularity and the variable expression factors some members of the litter may not show the fault whilst others are positive for it or whole litters can be free of the sign and yet carry the dominant gene.

Bearing in mind the condition is congenital there has to be a strong recommendation that all puppies in a litter, ideally with no exception, should be examined by ophthalmoscopic means prior to twelve weeks of age and best between six and eight weeks of age. This will entail the instillation of a pupil-dilating medicine into the eye in order that the whole of the lens can be visualised.

It should be possible by attention to detail in this fashion and not breeding from either affected animals or those in the same litter or by using the same mating again to reduce the fault quite rapidly. But it requires concerted action.

S.J. Foster