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L2HGA – L 2 Hydroxyglutaric Acidurea

L-2-HGA is a metabolic condition of Staffordshire Bull Terriers in which affected dogs lack an enzyme to properly break down a metabolic by-product, an organic acid, L-2-hydroxyglutaric acid. This compound then builds up in the cerebrospinal fluid and plasma of the affected dogs, causing the symptoms of this illness. Central nervous system symptoms include lack of coordination, tremors, personality disorders, poor learning abilities, and seizures. These affected dogs usually excrete high levels of the compound in their urine, hence the term “aciduria”. Unfortunately, treatment is entirely symptomatic; there is no cure. Affected dogs often must be euthanized at an early age, and even the more mildly affected will never behave like a “normal dog.”

L-2-HGA is now known to be transmitted by means of an autosomal recessive mode of inheritance. A simple DNA test, using a small sample of the dog’s blood, is now available which will identify carriers, clears, and affected for this condition in the Staffordshire Bull Terrier. A dog who is a carrier has one copy of the mutated gene, but does not itself show signs of the disease. The affected dog has both mutated copies of the gene and develops L-2-HGA, while the clear dog has two normal genes. A carrier, if bred to another carrier, will produce on average one affected puppy, two carriers, and one clear puppy for every four puppies produced. However, by using the new DNA test, breeders can test their breeding stock, and, based upon this test, breed appropriately to prevent affected puppies from being produced.

It is critical that all breeders use this new DNA test to screen their breeding stock for this mutation, since it is estimated (late 2006) that upwards of 15% of Staffords in some countries are carriers.

 

More information can be found via the following resources:

facebook.com/L2HGACanine

aht.org.uk/cms-display/genetics_l2hga

Hereditary (Juvenile) Cataracts

Hereditary Cataract is a hereditary condition that causes an opacity or cloudiness to develop in the lens of a dog’s eyes at a relatively early age. Although the eyes are normal at birth, bilateral cataracts form usually by several months of age. This condition often progresses rapidly, leading to total blindness by three years of age. Surgery (canine lens extraction using phacoemulsification) can be used to restore sight to the affected dog; however, it has only a 75% long term success rate in restoring useful vision.  Hereditary cataract is now known to be transmitted by means of an autosomal recessive mode of inheritance. A simple DNA test, using a small sample of the dog’s blood, is now available which will identify carriers, clears, and affecteds for this condition in the Staffordshire Bull Terrier.  A dog who is a carrier has one copy of the mutated gene, but does not itself show signs of the disease. The affected dog has both mutated copies of the gene and develops cataracts, while the clear dog has two normal genes. A carrier, if bred to another carrier, will produce on average one affected puppy, two carriers, and one clear puppy for every four puppies produced. By using the new DNA test, breeders can test their breeding stock, and, based upon this test, breed appropriately to prevent affected puppies from being produced. With limited testing in the U.S. approximately 8% of all U.S. Staffords tested for Hereditary Cataract have been shown to be carriers when this test was first widely introduced in 2007.

 

Hip Dysplasia

Hip Dysplasia is a crippling condition in which laxness in the hip joint causes premature breakdown of the cartilage lining, leading to arthritis. The tendency to hip dysplasia can be passed on from one generation to the next; researchers believe that it is a polygenic-based disorder, having more than one causative gene. Symptoms may include difficulty jumping or using stairs; unusual stiffness after exercise; and a peculiar “bunny-hopping” gait.  While there is a strong hereditary component to this affliction, many believe environmental factors, such as overfeeding leading to too-rapid growth in puppies, can cause the condition to progress much more rapidly if a genetic tendency is already present. Often, the effects of mild hip dysplasia are not seen until the dog is middle-age or older, and can be managed by weight control and anti-inflammatory medications. Occasionally, however, puppies and young dogs can show symptoms of hip dysplasia which are rapidly progressive and crippling; special surgical techniques have been developed for these dogs to help them lead a more normal and pain-free life. According to the latest OFA statistics (2012), with 577 Staffords having been evaluated using hip x-rays, 17.2% are rated abnormal (dysplastic), and 80.4% have both hips graded normal. Since this is at least partially a hereditary condition, careful breeding will reduce its incidence in a breed over time. If both parents have normal hips, there is a lessened possibility for one or more puppies in a litter to be later rated dysplastic. Tests can be performed via OFA Evaluation or PennHIP Evaluation

 

Eye Diseases – CERF / CAER

There are a few eye diseases in staffords.  This is not an exhaustive list of every possible disease however these are the most common in our breed.

 

Hereditary (Juvenile) Cataracts

Hereditary Cataract is a hereditary condition that causes an opacity or cloudiness to develop in the lens of a dog’s eyes at a relatively early age. Although the eyes are normal at birth, bilateral cataracts form usually by several months of age. This condition often progresses rapidly, leading to total blindness by three years of age. Surgery (canine lens extraction using phacoemulsification) can be used to restore sight to the affected dog; however, it has only a 75% long term success rate in restoring useful vision.  Hereditary cataract is now known to be transmitted by means of an autosomal recessive mode of inheritance. A simple DNA test, using a small sample of the dog’s blood, is now available which will identify carriers, clears, and affecteds for this condition in the Staffordshire Bull Terrier.  A dog who is a carrier has one copy of the mutated gene, but does not itself show signs of the disease. The affected dog has both mutated copies of the gene and develops cataracts, while the clear dog has two normal genes. A carrier, if bred to another carrier, will produce on average one affected puppy, two carriers, and one clear puppy for every four puppies produced. By using the new DNA test, breeders can test their breeding stock, and, based upon this test, breed appropriately to prevent affected puppies from being produced. With limited testing in the U.S. approximately 8% of all U.S. Staffords tested for Hereditary Cataract have been shown to be carriers when this test was first widely introduced in 2007.

 

Persistent Hyperplastic Primary Vitreous (PHPV)

Persistent Hyperplastic Primary Vitreous (PHPV) is an inherited eye condition found in Staffords as well as other breeds. In PHPV, embryonic blood vessels in the eye persist abnormally after birth, usually on the posterior lens capsule, interfering with the dog’s vision. A posterior cortical cataract may sometimes form, as well. PHPB is congenital, and not acquired nor progressive. Therefore, it can be detected on any eye exam performed at any age starting at six weeks or later, and it will not worsen from that point. While many cases are relatively mild, some can be quite severe and interfere materially with the dog’s vision. Mode of inheritance is unknown at this time, although some believe that it is autosomal dominant with incomplete penetrance. Surgery is available but it is not always entirely successful and can be very expensive. It is advised to limit the breeding of adult Staffords with this condition, so that it does not become a serious problem in the breed. However, if it is found to have incomplete penetrance genetically, it would still be possible for a dog to transmit the PHPV mutation without itself showing symptoms. The Animal Health Trust in England is currently working to develop a genetic test for this condition.

 

Posterior Polar Subcapsular Cataracts (PPSC)

Posterior Polar Subcapsular Cataracts (PPSC) involves the formation of a generally small cataract which does not typically produce total blindness in the dog. It occurs in Staffords, as well as a number of other breeds. Onset may be juvenile, or in adulthood. PPSC is thought to be hereditary, although the mode of transmission is still unknown. It is not related to Hereditary Cataracts. While PPSC can be readily detected on a standard eye exam, unfortunately the eye exam cannot determine whether or not the “clear” dog will develop this condition. Here also, surgery is a possibility but is not always successful, and can be very expensive. It is advisable to limit breeding of dogs known to have PPSC to ensure that this condition will not become a problem in the breed. Unfortunately, if onset is not until adulthood, it is possible that a breeder may still use such a dog in their program before the cataract develops and is observed. For this reason, eye exams are recommended annually for every Stafford in a breeding program. There is no genetic testing available for this condition at this time.

 

 

Patellar Luxation (Optional) via OFA Evaluation

is a condition in which the patella, or kneecap, of the dog’s stifle joint frequently luxates or “pops” out of place. Depending upon the severity, symptoms can be intermittent and mild throughout the dog’s life, with the only evidence of the condition an occasional funny “kick” of the dog’s hind leg, or it may eventually lead to severe, permanent degenerative changes in the joint including arthritis. Infrequently, onset may appear to be sudden, leaving the dog unable to stand on the affected hindleg(s). Patellar luxation is believed to be hereditary, as well, although the exact mode of transmission is uncertain. According to the latest OFA statistics (2012), with 72 Staffords having been evaluated radiographically (using x-rays), 100% were evaluated as “normal.” However, these statistics are considered misleading, not only because of the small sample size evaluated, but also because patellar luxation is known for certain to occasionally be found in this breed.

 

Elbow Dysplasia (Optional) via OFA Evaluation

The term elbow dysplasia is used to describe a degenerative disorder of the elbow joint caused by improper development of a portion of a particular bone in this joint (anconeal process of the ulna). Young dogs that have this condition often exhibit pain when jumping or turning quickly, or may show variable foreleg lameness. It is thought to be hereditary in nature, and tends to run in canine families. However, exogenous causes, such as over-feeing a puppy into too-rapid growth, may be partially to blame as well, especially if a genetic tendency is present. Injury to the joint might also be a cause. Depending upon the age of the dog, the actual cause, and the severity of the symptoms, treatment can include modalities ranging from anti-inflammatories medications up to surgery. According to the latest OFA statistics (2012), with 217 Staffords having been evaluated using elbow x-rays, 16.6% of these Staffords have elbow dysplasia, while 82.9% are rated as having normal elbows. Cardiac Evaluation (Optional) via Congenital Cardiac Exam OR Advanced Cardiac Exam

Congenital heart diseases in dogs are malformations of the heart or great vessels. The lesions characterizing congenital heart defects are present at birth and may develop more fully during perinatal and growth periods. Many congenital heart defects are thought to be genetically transmitted from parents to offspring; however, the exact modes of inheritance have not been precisely determined for all cardiovascular malformations.