Health Tests For Labradors

The main purpose of the British Veterinary Association/Kennel Club (BVA/KC) Elbow Dysplasia Scheme is the examination of radiographs of the elbows of dogs for elbow dysplasia and the issue of a certificate in respect of that examination.

Elbow Dysplasia (ED) describes the abnormal development of the elbow. The term includes a number of specific abnormalities, which affect different sites in the joint. They cause problems by affecting the growth of the cartilage which forms the surface of the joint, or the structures around it. These abnormalities, called primary lesions, then start a secondary osteoarthritic process.

A grade for each elbow is calculated from the presence of the primary lesions and the size and extent of the secondary lesions. The overall grade for an animal is simply the higher of the two individual grades. The grades for each elbow are not added together as they are for the two hips in the hip dysplasia scheme.

The grading system is as follows:

0 – Normal
1 – Mild ED
2 – Moderate ED or a primary lesion
3 – Severe ED

The BVA advise breeders to select dogs with grades of 0 or 1 in order to reduce the risk of ED in their offspring.

The ANKC hip scoring scheme uses a similar scoring system to the BVA/KC scheme in the UK.

The lower the score the less the degree of hip dysplasia present. The minimum (best) score for each hip is zero and the maximum (worst) is 53 giving a possible range of 0-106.

The ANKC publishes a list of the Breed Median Scores

The ANKC elbow scoring scheme uses a similar scoring system to the BVA/KC scheme in the UK.

The grading system is as follows:

0 – Normal
1 – Mild ED
2 – Moderate ED or a primary lesion
3 – Severe ED

For over 30 years BVA (British Veterinary Association) has operated a hereditary eye disease screening program in conjunction with the Kennel Club (KC) and the International Sheep Dog Society (ISDS). The main purpose of the scheme is to ensure that there is no evidence of hereditary eye disease in dogs used for breeding. The scheme now covers 11 hereditary eye conditions in over 50 breeds of dogs.

There are two categories of inherited eye disease:

Congenital (present from birth)
Non-congenital (acquired later in life)
The scheme tests for the following congenital conditions:

Glaucoma
Persistent hyperplastic primary vitreous (PHPV)
Retinal dysplasia
Collie eye anomaly (CEA)
Congenital hereditary cataract
And the following non-congenital conditions:

Hereditary cataract
Primary lens luxation
Generalized progressive retinal atrophy (GPRA)
Retinal pigment epithelial dystrophy
Breeders are advised to submit dogs for annual eye tests since some diseases have late onset of clinical signs.

It is also possible for litters to be tested for congenital hereditary conditions such as Collie eye anomaly and Multifocal retinal dysplasia when they are between six and twelve weeks of age.

The prcd-PRA test is a DNA-based test that helps you avoid one form of Progressive Retinal Atrophy (PRA). PRA refers to a group of diseases that cause the retina of the eye to degenerate slowly over time. The result is declining vision and eventual blindness. “prcd” stands for “progressive rod-cone degeneration” which is the type of PRA known in several breeds.

The genetic disorder, prcd-PRA , causes cells in the retina at the back of the eye to degenerate and die, even though the cells seem to develop normally early in life. The “rod” cells operate in low light levels and are the first to lose normal function. Night blindness results. Then the “cone” cells gradually lose their normal function in full light situations. Most affected dogs will eventually be blind.

The DNA prcd test is done on a small sample of blood from the dog. The test analyzes the specific DNA mutation causing prcd-PRA. The DNA test detects the mutant, the abnormal gene copy and the normal gene copy. The result of the test is a genotype and allows the separation of dogs into three groups: Normal/Clear (homozygous normal), Carrier (heterozygous), and Affected (homozygous mutant).

Possible results using the DNA prcd test

Normal – Can be bred to any dog, extremely low risk of producing affected
Carrier – Should be bred only to Normal to remove the risk of producing affected
Affected – Should be bred only to Normal to remove the risk of producing affected

Hereditary nasal parakeratosis (HNPK) is a condition where Affected dogs develop crusts and fissuring of the nose pad at a young age but are otherwise healthy. In severe cases, painful fissures will appear. Also known as Hyperkeratosis it is inherited as a monogenic autosomal recessive skin disease. HNPK currently cannot be cured, but the symptoms can be alleviated with symptomatic therapy. Normal: The dog carries two copies of the normal gene and will not pass over the HNPK mutation to its offspring. Carrier: The dog carries one mutant and one normal copy of the HNPK gene. The dog will pass over one copy of the mutated gene to approximately 50% of its offspring. Affected: The dog carries two mutant copies of the gene and suffers from hereditary nasal parakeratosis.

Exercise Induced Collapse is an inherited condition that affects Labrador Retriever and related breeds. Affected dogs can endure mild to moderate exercise but after 5 to 20 minutes of heavy exercise with extreme excitement, the dog shows weakness and then collapse. Severely affected dogs may collapse whenever they are exercised to this extent – other dogs only exhibit collapse episodes sporadically. Signs of EIC are not typically seen until the dog begins intense training. First symptoms are usually noted between 5 months and 3 years of age. However, it is confirmed that some affected dogs did not have collapse episodes until as late as age 10.

Skeletal dysplasia 2 is a genetic disease in Labrador Retrievers that causes an early halt in the growth of long bones. In contrast to other forms of dwarfism (pituitary dwarfism), the result is ‘disproportioned’ dogs with shortened front limbs and a raising dorsal line. Torso length and depth are not altered. Based on the latest knowledge, affected dogs do not exhibit further symptoms like malformed genitals or neuronal diseases as in pituitary dwarfism.

Centronuclear myopathy (CNM) in Labrador Retrievers is a hereditary myopathy characterized by skeletal muscle problems such as muscle weakness and exercise intolerance. It is also known as hereditary myopathy of the Labrador Retriever (HMLR).

Stargardt disease (STGD) is an inherited retinal degenerative disease that leads to visual impairment and blindness. It is caused by the degeneration of both rod and cone-type photoreceptor cells of the retina. These cells are important for vision in dim and/or bright light. Dogs affected with the condition start to show signs of the disease before they reach 10 years of age. Dilated pupils and decreased response to light are common signs.

Macular corneal dystrophy (MCD) is a hereditary disease that can affect middle-aged Labrador Retrievers. Affected dogs will develop cloudy eyes, due to an abnormal accumulation of glycosaminoglycans (carbohydrates) in their corneas (the equivalent to the windscreen of the eye). The disease is progressive, and although not painful, can cause marked visual impairment in affected dogs. The only treatment for the disease in people is surgical (corneal transplant), however, this has not yet been performed successfully in the dog for the treatment of canine MCD.

The MLPH gene codes for a protein called melanophilin, which is responsible for transporting and fixing melanin-containing cells. A mutation in this gene leads to improper distribution of these cells, causing a dilute coat colour. This mutation is recessive so two copies of the mutated gene (or “d” allele) are needed to produce the dilute coat colour.

This mutation affects both eumelanin and phaeomelanin pigments, so black, brown, and yellow dogs are all affected by the dilution. However, this effect is more pronounced in black dogs. A dilute black (BB or Bb) dog is generally known as blue, though names do vary for different breeds, such as charcoal or grey. A diluted chocolate (bb) dog is often referred to as lilac and a diluted yellow (ee) is known as champagne.

Because the mutation responsible for the dilution phenotype is recessive, a dog can be a carrier of the dilution gene and still appear to have a normal coat colour. These dogs can pass on either the full-coloured or dilute allele to any offspring. This means that two dogs that appear full-coloured can have dilute puppies. This makes DNA testing for the D-Locus an important breeding tool, whether breeding for a dilute coat or avoiding it.

Degenerative myelopathy is a progressive disease of the spinal cord in older dogs.

The disease has an insidious onset typically between 8 and 14 years of age. It begins with a loss of coordination (ataxia) in the hind limbs. The affected dog will wobble when walking, knuckle over or drag the feet. This can first occur in one hind limb and then affect the other. As the disease progresses, the limbs become weak and the dog begins to buckle and has difficulty standing. The weakness gets progressively worse until the dog is unable to walk.