DNA TESTING

DNA Tests are only available for the following issues in Staffordshire Bull Terriers -

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Degenerative Myelopathy

Nervous system / Neurologic - Associated with the brain, spinal cord and nerves

Signs are due to the immune-mediated destruction of a part of the nerves in the spinal cord, leading to loss of these nerve fibres. The first sign is knuckling of the hind feet, and hind limb ataxia. Following this initial stage, hind limb reflexes are affected, then weakness in the hind limbs develops, progressing to total paralysis. Once a dog shows these signs it will almost always respond poorly to therapy. Eventually destruction progresses from the middle of the spinal cord to the upper cord and brain stem, leading to forelimb weakness and eventually interference with the muscles of breathing, causing death. 

 

Hereditary Cataract

Ophthalmologic - Associated with the eyes and associated structures

Most cases of cataract in dogs are of an inherited form. This disease causes cloudiness in the lens of the eye. This cloudiness may be located in the centre of the lens, or towards the front or the back of the lens. Inherited cataract is almost always bilateral (that is, in both eyes). Cataract may also progress (get worse) at varying rates, resulting in initial blurred vision which may often progress to complete blindness

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L2- Hydroxyglutaric Aciduria

Nervous system / Neurologic - Associated with the brain, spinal cord and nerves

L-2 Hydroxyglutaric Aciduria is an inherited neurometabolic disorder. Affected dogs have increased levels of L-2-hydroxyglutaric acid in urine, blood and cerebrospinal fluid and progressive damage to the brain. L-2-HGA is an autosomal recessive metabolic disease that causes an increase in levels of the substance L-2-hydroxyglutaric acid in the blood, urine and CSF (the fluid around the brain and spinal cord). This substance is toxic to cells of the central nervous system, and causes muscle stiffness, tremors and seizures, a wobbly gait and altered behaviour. Signs usually appear at around 6 – 12 months of age, although it can occur later. A DNA test is available for Staffordshire Bull Terriers, but in other breeds diagnosis is through blood or urine tests to show elevated levels of L-2-HGA. There is no treatment available for this disease.

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DNA RESULTS

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• CLEAR: the dog has 2 copies of the normal gene and will neither develop the disease/issue nor pass a copy of the disease 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 the disease. It will not develop the issue but will pass on the gene to 50% (on average) of its offspring.

• AFFECTED: the dog has two copies of the disease mutation and is affected with the disease. It will develop the disease/issue 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 affected 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.

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OTHER EYE ISSUES

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There are several issues that effect Staffords eyes. Currently there are no DNA Markers for these which means they can only be affected or unaffected and it is unknown if they can pass on the condition. These eye conditions can only be tested for by a qualified Vet Ophthalmologist under the ACES Eye Scheme tested animals will be issued with an Eye Certificate and any departures from normal are noted.

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Distichiasis (‘extra eyelashes’)

Distichiasis is a condition in which extra hairs grow out of the eyelash area. It happens when there are two or more hairs growing out of a Meibomian gland opening. (Meibomian glands are located along the margin of the eyelid.) These hairs are not supposed to be there. In some cases, these extra hairs can be long and stiff and irritate the eye, resulting in a corneal ulcer. In many dogs the extra eyelashes do not cause a problem, but in some cases they can rub the surface of the eye and cause irritation. The most common signs that you will notice are increased blinking/squinting of the eye, increased watering, and redness of the ‘white’ of the eye.

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PHPV (Persistent Hyperplastic Primary Vitreous)

This is a congenital condition (present from birth) in which there is a developmental defect in the normal regression of some of the intraocular structures of the eye. PHPV can range from being very mild to severe abnormalities which may lead to blindness. Due to PHPV seldom resulting in secondary cataracts in the Stafford, those that are mildly afflicted will seldom show any form of visual impairment during the course of their lives. Even those that are more severely afflicted, may be capable of adapting by using peripheral to compensate.

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OTHER HEALTH ISSUES

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Hip Dysplasia

Research has shown that the cause of hip dysplasia is related to a combination of genetic and environmental factors. The disease is known to be an inherited condition and the genetics of hip dysplasia are extremely complicated. In addition, environmental factors such as overfeeding and excessive exercise can predispose a dog (especially growing puppies) to developing hip dysplasia.

The Australian Veterinary Association runs a scheme (AVA / ANKC Canine Hip & Elbow Dysplasia Scheme (CHEDS) under which your dog's x-rays will receive a score from an expert. Since in some HD prone breeds it is virtually impossible to find an animal that is hip dysplasia free, the object is to ensure that you breed from a dog whose score is better (lower) than the breed average score. In this way the chances of reducing the incidence of the disease are greatly increased.

Avoid excessive exercise in a growing puppy. Any abnormality in the structure of the hip joint is magnified if excessive running and jumping occur. It is not necessary to treat your puppy as if it were disabled, but long sessions of running or repetitively chasing thrown objects, running on the beach, up/down stairs or alongside a bike can be detrimental to joints.

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