The Importance of Genetic testing
All breeds of dogs have there share of genetic health problems. Labrador Retrievers are no exeption. While searching for your next Lab puppy be sure the breeder provides the following genetic testing. The following are the MINIMUM that breeders of Labrador Retrievers should be performing.
Hip Dysplasia: Hip Dysplasia is a terrible genetic disease because of the various degrees of arthritis (also called degenerative joint disease, arthrosis, osteoarthrosis) it can eventually produce, leading to pain and debilitation.
The very first step in the development of arthritis is articular cartilage (the type of cartilage lining the joint) damage due to the inherited bad biomechanics of an abnormally developed hip joint. Traumatic articular fracture through the joint surface is another way cartilage is damaged. With cartilage damage, lots of degradative enzymes are released into the joint. These enzymes degrade and decrease the synthesis of important constituent molecules that form hyaline cartilage called proteoglycans. This causes the cartilage to lose its thickness and elasticity, which are important in absorbing mechanical loads placed across the joint during movement. Eventually, more debris and enzymes spill into the joint fluid and destroy molecules called glycosaminoglycan and hyaluronate which are important precursors that form the cartilage proteoglycans. The joint's lubrication and ability to block inflammatory cells are lost and the debris-tainted joint fluid loses its ability to properly nourish the cartilage through impairment of nutrient-waste exchange across the joint cartilage cells. The damage then spreads to the synovial membrane lining the joint capsule and more degradative enzymes and inflammatory cells stream into the joint. Full thickness loss of cartilage allows the synovial fluid to contact nerve endings in the subchondral bone, resulting in pain. In an attempt to stabilize the joint to decrease the pain, the animal's body produces new bone at the edges of the joint surface, joint capsule, ligament and muscle attachments (bone spurs). The joint capsule also eventually thickens and the joint's range of motion decreases.
No one can predict when or even if a dysplastic dog will start showing clinical signs of lameness due to pain. There are multiple environmental factors such as caloric intake, level of exercise, and weather that can affect the severity of clinical signs and phenotypic expression (radiographic changes). There is no rhyme or reason to the severity of radiographic changes correlated with the clinical findings. There are a number of dysplastic dogs with severe arthritis that run, jump, and play as if nothing is wrong and some dogs with barely any arthritic radiographic changes that are severely lame.
The usual treatments are pain killers and/or surgury. The Labrador Retriever ranks 82nd among pure bred dog breeds likely to have hip dysplasia. OFA hip evaluations fall into one of seven catagories: NORMAL (excellent, good, fair), BORDERLINE, & DYSPLASTIC (mild, moderate, severe). From January 1974 to December 2009 there have been 208931 Labrador Retriever hip x-rays submitted to the Orthopedic Foundation for Animals for hip dysplasia evaluation. Of that number 17.6 % were graded excellent and 12 % were considered dysplastic.
Hip Dysplasia screening by the OFA, PennHip, or OVC is recommended for all Labrador Retrievers used for breeding. Expense for this is around $200.00 to $300.00 plus fees.
Elbow Dysplasia: Elbow dysplasia is a general term used to identify an inherited polygenic disease in the elbow of dogs. Three specific etiologies make up this disease and they can occur independently or in conjunction with one another. These etiologies include:
1.Pathology involving the medial coronoid of the ulna (FCP)
2.Osteochondritis of the medial humeral condyle in the elbow joint (OCD)
3.Ununited anconeal process (UAP)
Studies have shown the inherited polygenic traits causing these etiologies are independent of one another. Clinical signs involve lameness which may remain subtle for long periods of time. No one can predict at what age lameness will occur in a dog due to a large number of genetic and environmental factors such as degree of severity of changes, rate of weight gain, amount of exercise, etc. Subtle changes in gait may be characterized by excessive inward deviation of the paw which raises the outside of the paw so that it receives less weight and distributes more mechanical weight on the outside (lateral) aspect of the elbow joint away from the lesions located on the inside of the joint. Range of motion in the elbow is also decreased. The statisics for ED in Labradors is shown below:
1990 thru 1993 3,492 Labradors evaluated, 11.5% ED
1994 thru 1997 8,915 Labradors evaluated, 12.3% ED
1998 thru 2001 10,703 Labradors evaluated, 10.1% ED
Elbow Dysplasia screening by the OFA or OVC is recommended for all Labrador Retrievers used for breeding. The expense for this is $50.00 to $100.00 in addition to the hip radiographs.
Progressive Retinal Atrophy: is a group of genetic diseases seen in certain breeds of dogs. It is characterized by the bilateral degeneration of the retina, causing progressive vision loss culminating in blindness. The condition in nearly all breeds is inherited as an autosomal recessive trait. There is no treatment.
All Labrador Retrievers between the ages of 1 to 9 used for breeding should have an annual eye exam by a Veterinary Opthalmologist certified by the American College of Veterinary Opthalmologists. Expense for this test is around $25.00 plus $7.00 for the CERF registration.
Centronuclear Myopathy: CNM is an enherited health condition found in field bred Labradors that weakens the muscles making walking difficult. The disease starts in puppies and reaches a climax at about 1 year old. Affected dogs show signs similar to humans with muscular dystrohy. To be affected a dog must have two abnormal genes. One from each parent. A dog with one abnormal gene will not shpw symptoms but will pass the condition on to it's offspring if bred with another carrier. There is no cure for CNM but a DNA based test is used to determine if a dog is clear of the abnormal gene.
All Labrador Retrievers used for breeding should be tested for CNM before being bred. The test costs about $70.00.
Exercise Enduced Collapse: EICAffected dogs can tolerate mild to moderate exercise, but 5 to 20 minutes of strenuous exercise with extreme excitement induces weakness and then collapse. Severely affected dogs may collapse whenever they are exercised to this extent - other dogs only exhibit collapse sporadically. The first thing noted is usually a rocking or forced gait. The rear limbs then become weak and unable to support weight. Many affected dogs will continue to run while dragging their back legs. Some of the dogs appear to be incoordinated, especially in the rear limbs, with a wide-based, long, loose stride rather than the short, stiff strides typically associated with muscle weakness. In some dogs the rear limb collapse progresses to forelimb weakness and occasionally to a total inability to move. Some dogs appear to have a loss of balance and may fall over, particularly as they recover from complete collapse. Most collapsed dogs are totally conscious and alert, still trying to run and retrieve but as many as 25% of affected dogs will appear stunned or disoriented during the episode. A dog must have two abnormal genes to be affected with EIC. One form each parent. Dogs with only one abnormal gene are carriers but will not be affected.
All Labrador Retrievers used for breeding should be tested for EIC before being bred. the cost is around $65.00.
Make sure the prospective breeders have done these tests on BOTH SIRE AND DAM before buying a puppy from the litter. Ask to see proof of these clearances. The OFA wesite has a searchable database for dogs that shows what clearances they have. If you buy a puppy without these clearances but at your own risk. Having these clearances greatly reduces the chances of genetic problems down the road.
Hip Dysplasia: Hip Dysplasia is a terrible genetic disease because of the various degrees of arthritis (also called degenerative joint disease, arthrosis, osteoarthrosis) it can eventually produce, leading to pain and debilitation.
The very first step in the development of arthritis is articular cartilage (the type of cartilage lining the joint) damage due to the inherited bad biomechanics of an abnormally developed hip joint. Traumatic articular fracture through the joint surface is another way cartilage is damaged. With cartilage damage, lots of degradative enzymes are released into the joint. These enzymes degrade and decrease the synthesis of important constituent molecules that form hyaline cartilage called proteoglycans. This causes the cartilage to lose its thickness and elasticity, which are important in absorbing mechanical loads placed across the joint during movement. Eventually, more debris and enzymes spill into the joint fluid and destroy molecules called glycosaminoglycan and hyaluronate which are important precursors that form the cartilage proteoglycans. The joint's lubrication and ability to block inflammatory cells are lost and the debris-tainted joint fluid loses its ability to properly nourish the cartilage through impairment of nutrient-waste exchange across the joint cartilage cells. The damage then spreads to the synovial membrane lining the joint capsule and more degradative enzymes and inflammatory cells stream into the joint. Full thickness loss of cartilage allows the synovial fluid to contact nerve endings in the subchondral bone, resulting in pain. In an attempt to stabilize the joint to decrease the pain, the animal's body produces new bone at the edges of the joint surface, joint capsule, ligament and muscle attachments (bone spurs). The joint capsule also eventually thickens and the joint's range of motion decreases.
No one can predict when or even if a dysplastic dog will start showing clinical signs of lameness due to pain. There are multiple environmental factors such as caloric intake, level of exercise, and weather that can affect the severity of clinical signs and phenotypic expression (radiographic changes). There is no rhyme or reason to the severity of radiographic changes correlated with the clinical findings. There are a number of dysplastic dogs with severe arthritis that run, jump, and play as if nothing is wrong and some dogs with barely any arthritic radiographic changes that are severely lame.
The usual treatments are pain killers and/or surgury. The Labrador Retriever ranks 82nd among pure bred dog breeds likely to have hip dysplasia. OFA hip evaluations fall into one of seven catagories: NORMAL (excellent, good, fair), BORDERLINE, & DYSPLASTIC (mild, moderate, severe). From January 1974 to December 2009 there have been 208931 Labrador Retriever hip x-rays submitted to the Orthopedic Foundation for Animals for hip dysplasia evaluation. Of that number 17.6 % were graded excellent and 12 % were considered dysplastic.
Hip Dysplasia screening by the OFA, PennHip, or OVC is recommended for all Labrador Retrievers used for breeding. Expense for this is around $200.00 to $300.00 plus fees.
Elbow Dysplasia: Elbow dysplasia is a general term used to identify an inherited polygenic disease in the elbow of dogs. Three specific etiologies make up this disease and they can occur independently or in conjunction with one another. These etiologies include:
1.Pathology involving the medial coronoid of the ulna (FCP)
2.Osteochondritis of the medial humeral condyle in the elbow joint (OCD)
3.Ununited anconeal process (UAP)
Studies have shown the inherited polygenic traits causing these etiologies are independent of one another. Clinical signs involve lameness which may remain subtle for long periods of time. No one can predict at what age lameness will occur in a dog due to a large number of genetic and environmental factors such as degree of severity of changes, rate of weight gain, amount of exercise, etc. Subtle changes in gait may be characterized by excessive inward deviation of the paw which raises the outside of the paw so that it receives less weight and distributes more mechanical weight on the outside (lateral) aspect of the elbow joint away from the lesions located on the inside of the joint. Range of motion in the elbow is also decreased. The statisics for ED in Labradors is shown below:
1990 thru 1993 3,492 Labradors evaluated, 11.5% ED
1994 thru 1997 8,915 Labradors evaluated, 12.3% ED
1998 thru 2001 10,703 Labradors evaluated, 10.1% ED
Elbow Dysplasia screening by the OFA or OVC is recommended for all Labrador Retrievers used for breeding. The expense for this is $50.00 to $100.00 in addition to the hip radiographs.
Progressive Retinal Atrophy: is a group of genetic diseases seen in certain breeds of dogs. It is characterized by the bilateral degeneration of the retina, causing progressive vision loss culminating in blindness. The condition in nearly all breeds is inherited as an autosomal recessive trait. There is no treatment.
All Labrador Retrievers between the ages of 1 to 9 used for breeding should have an annual eye exam by a Veterinary Opthalmologist certified by the American College of Veterinary Opthalmologists. Expense for this test is around $25.00 plus $7.00 for the CERF registration.
Centronuclear Myopathy: CNM is an enherited health condition found in field bred Labradors that weakens the muscles making walking difficult. The disease starts in puppies and reaches a climax at about 1 year old. Affected dogs show signs similar to humans with muscular dystrohy. To be affected a dog must have two abnormal genes. One from each parent. A dog with one abnormal gene will not shpw symptoms but will pass the condition on to it's offspring if bred with another carrier. There is no cure for CNM but a DNA based test is used to determine if a dog is clear of the abnormal gene.
All Labrador Retrievers used for breeding should be tested for CNM before being bred. The test costs about $70.00.
Exercise Enduced Collapse: EICAffected dogs can tolerate mild to moderate exercise, but 5 to 20 minutes of strenuous exercise with extreme excitement induces weakness and then collapse. Severely affected dogs may collapse whenever they are exercised to this extent - other dogs only exhibit collapse sporadically. The first thing noted is usually a rocking or forced gait. The rear limbs then become weak and unable to support weight. Many affected dogs will continue to run while dragging their back legs. Some of the dogs appear to be incoordinated, especially in the rear limbs, with a wide-based, long, loose stride rather than the short, stiff strides typically associated with muscle weakness. In some dogs the rear limb collapse progresses to forelimb weakness and occasionally to a total inability to move. Some dogs appear to have a loss of balance and may fall over, particularly as they recover from complete collapse. Most collapsed dogs are totally conscious and alert, still trying to run and retrieve but as many as 25% of affected dogs will appear stunned or disoriented during the episode. A dog must have two abnormal genes to be affected with EIC. One form each parent. Dogs with only one abnormal gene are carriers but will not be affected.
All Labrador Retrievers used for breeding should be tested for EIC before being bred. the cost is around $65.00.
Make sure the prospective breeders have done these tests on BOTH SIRE AND DAM before buying a puppy from the litter. Ask to see proof of these clearances. The OFA wesite has a searchable database for dogs that shows what clearances they have. If you buy a puppy without these clearances but at your own risk. Having these clearances greatly reduces the chances of genetic problems down the road.