Genetic Disease Testing
Genetic Disease Testing has been done on the Sire & Dam (Parents). There are approx. 30 current genetic tests that relate to Labradors, with 19 of them have some form of affect on the quality of your dogs life and the balance either have no medical affect or are associated with colour and coat genetics. Whilst most of the 19 diseases are very rare it is still something to take into consideration when deciding on a breeder.
Ask to see a copy of both the Sire and Dams Genetic results and ensure that they are a Certified Result (Swab has been taken by an Approved Collection Agent or Vet) if they aren’t already on the breeders website. It is not compulsory to do Genetic DNA testing in some states but most reputable ANKC Breeders do test.
Understanding Genetic terminology doesn’t need to be scary and you don’t need a medical degree. Many of the diseases that present in Labradors are auto recessive which means that for the disease to be present it requires two copies of the affected gene, one from the sire (father) and one from the dam (mother). Dogs can be:
Negative / Clear: Not Affected / No Variant Detected.
Carrier: Not Affected / One Copy of the Variant Detected
Affected: Affected
Expected Outcomes based on Mendelian Genetics (these may vary due to the probability of inheritance not being equal).
Clear to Clear: Litter 100% Not Affected. All puppies clear of any genetic issues.
Clear to Carrier: Litter 100% Not Affected but 50% may be Carriers
Carrier to Carrier: Litter 75% Not Affected & 25% Affected. 50% of the Not Affected being Carriers.
Affected to Affected: Litter 100% Affected
All Chava Labs dogs who are candidates for the breeding program undergo genetic testing to ensure soundness and health, both of the parents and any resulting puppies.
We've put together a glossary of some of the genetic conditions that can be prevalent amongst Labrador Retrievers for you.
Genetic Conditions Glossary
Musculoskeletal.
Centronuclear Myopathy in Labradors is an inherited congenital disorder characterised by an excessive number of internalised nuclei. This causes insufficient muscle function and characterised by generalised muscle weakness caused by a defect in the mechanism by which muscle fibres are formed. At first a puppy will seem normal, but with puppy’s aging, CNM starts to show. Within 2 – 5 months clinical features in pups will include hypotonia (decreased muscle tone), generalised muscle weakness, abnormal postures, stiff hopping gait, exercise intolerance and increased collapse when exposed to cold and usually progresses in severity until approximately 1 year of age when the condition stabilises, however, some dogs may experience problems swallowing and are at risk of sudden death through choking or respiratory infection.
No cure for CNM has been developed and affected dogs will never develop properly functioning muscle tissue and may be unable to walk and exercise normally. Dogs can live normally but limited and affected by symptoms of CNM. Moderate severity which can cause significant signs of discomfort and/or dysfunction in affected animals and may involve relatively high treatment/management costs and can sometimes reduce life expectancy.
An inherited muscle disease known to affect Labrador Retrievers. Affected puppies are typically normal at birth, but between 7 and 19 weeks of age they present with muscle weakness especially in the hind limbs, decreased muscle mass, a hoarse bark and difficulty eating. Puppies are smaller than littermates, walk with a short, choppy gait and often fall over. The disease rapidly progresses from generalized muscle weakness and frequent episodes of collapse to a complete inability to stand or even raise their heads within 4 weeks of initial presentation. Dogs that are able to stand have an arched back and neck. While the disease is not painful, affected dogs are often euthanized between 3 and 6 months of age due to the rapid and severe progression of the disease.
Dogs inheriting SD2 develop legs that are shorter than the recognized breed standard despite a normal sized body. Most commonly, front limbs are more severely affected than hind legs with this disorder. The ulna and radius bones of the front limbs may also be slightly more bent in comparison to normal dogs.
Opthalmolgic (Eyes).
Opthalmolgic (Associated with the eyes and associated structures). Moderate severity which can cause significant signs of discomfort and/or dysfunction in affected animals. It may involve relatively high treatment/management costs and can sometimes reduce life expectancy.
Is a relatively rare disease which is inherited as an autosomal recessive
train, meaning that both parents must be at least carriers of the disease to product an affected offspring. The disease is characterised by a diffuse cloudiness of the cornea as well as an abnormally thin cornea in affected animals. Affected dogs will develop cloudy eyes, due to an abnormal accumulation of glycosaminoglycans in their corneas. Low-Moderate severity which can cause some discomfort and/or dysfunction in the affected animals and does not generally affect life expectancy.
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. Low-Moderate severity which can cause some discomfort and/or dysfunction in the affected animal and does not generally affect life expectancy.
Is a progressive disease and symptoms include blurred
vision and a difficuly trying to adapt from bright light to dark (dim) light and also referred to a Juvenile Macular Degeneration. Low-Moderate severity which can cause some discomfort and/or dysfunction in the affected animal and does not generally affect life expectancy.
Haemolymphatic (blood & lymph).
A condition characterised by oversized platelets and a low platelet count. Platelets in affected dogs’ function normally and affected dogs do not show any health problems or prolonged bleeding time. Low-Moderate severity and can cause some discomfort and/or dysfunction in the affected animal but does not generally affect life expectancy.
Canine Elliptocytosis is a rare inherited blood disorder. Normal red blood cells are round in shape but red blood cells in affected dogs appear oval-shaped and can have serrated edges. An affected dog may present with mild Anemia and may be smaller than its littermates. Severe health complications have not been reported in affected dogs. Low-Moderate severity which can cause some discomfort and/or dysfunction in the affected animal and generally does not affect life expectancy.
Nervous System/Neurologic.
Belongs in a group of conditions, known as Congenital myasthenic syndromes (CMS). It is an inherited neuromuscular transmission disorder which results in structural or functional defects of the neuromuscular junction, the place where nerve and muscle cells meet. Affected dogs can run normally for 5 – 30 minutes after which they take shorter and shorter strides and eventually fall down with flexed fore and hindlegs. After some minutes rest, they can walk and run again for variable periods of time before the signs reappear. Moderate severity which can cause significant signs of discomfort and/or dysfunction in affected animals and may involve relatively high treatment/management costs and can sometimes reduce life expectancy.
This disease is normally seen around middle age, and in general diagnosis can only be confirmed at a post mortem examination. 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. Once the spinal cord damage progresses past this initial stage, the effectiveness (if any) of treatment is much diminished. Hence early diagnosis is vital.
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.
Most dogs are euthanised for humane reasons before this happens. Treatment is with specific supplements and drugs aimed at interfering with the immune destruction in the spinal cord. To slow further nerve damage. The effectiveness of this treatment is variable but is only of benefit if started as early as possible. Once nerves are lost, they will not be replaced. Moderate severity and can cause significant signs of discomfort and/or dysfunction in affected animals and may involve relatively high treatment/management costs and can sometimes reduce life expectancy.
Signs are usually first seen in young adults, between 6 months and 3 years of age. With vigorous exercise lasting 5 – 20 minutes, a loss of control becomes apparent in the hind limbs. Starting as a wobbly gait, the loss of control progresses to collapse, and sometimes dogs may seem confused. Occasional deaths have been reported, so it is important that exercise is stopped as soon as signs first appear. Excitement and high temperatures and/or humidity may exacerbate signs. Low-Moderate severity and can cause some discomfort and/or dysfunction in the affected animal and does not generally affect life expectancy.
Typically present between 1 – 6 months of age with an inability to stay awake for extended periods of time and episodes of collapse and sleep following positive stimulation such as play or food. Affected dogs fall asleep faster than normal dogs an appear sleepy more frequently. During episodes of collapse dogs have a sudden loss of muscle tone and appear uncontrollably sleepy but may or may not completely fall asleep.. Symptoms do not progress after one year of age and affected dogs do not have other associated health problems. Low-Moderate severity which can cause some discomfort and/or dysfunction in the affected animals and does not generally affect life expectancy.
Urologic (kidneys, bladder, ureters & urethra)
A genetic defect in the kidney tubules. Normal kidneys filter the amino acid cystine and do not allow it to go into the urine. In dogs with cystinuria, this filtering action fails, and cystine passes into the urine, where it can form crystals and/or stones (uroliths). If stones form, they can block the urethra and obstruct urinary flow, especially in males.
This trait predisposes dogs to have elevated levels of uric acid in the urine which can form crystals and/or stones in the urinary tract. Dogs most commonly present with symptoms of recurrent urinary tract inflammation, which include frequent urination, blood in the uring, and straining to urinate. They may also have loss of appetite, lethargy, weakness, vomiting and pain. Urinary stones in the bladder can cause urinary tract infections or more seriously, blockage of the Urethra. Both male and female dogs can be affected, but obstruction of urine flow is more common in males due to differences in anatomy. Low-Moderate severity which can cause some discomfort and/or dysfunction in the affected animal and does not generally affect life expectancy.
Dermatologic (skin).
Is a group of connective tissue disorders that are characterised by fragile, stretchy and loose skin, cause by a genetic defect in the production of collagen. Low-Moderate severity which can cause some discomfort and/or dysfunction in the affected animal. It does not generally affect life expectancy.
Affected dogs begin showing clinical signs around six to twelve months of age. They develop dry, rough crusts on the tip of the nose. In extreme cases, the dog’s nose will crack causing severe discomfort. Lesions can occur on the area around the nose. The noses of these affected dogs are prone to bacterial infections and can lose pigment over time. This disorder may be treated with veterinary consultation and topical therapy. Low severity and generally causes mild signs of disease or can be quite easily treated/managed.
Metabolic.
Malignant hyperthermia is a grim condition in dogs that can lead to muscular diseases. It is an inherited mutation of the dominant genes that results in serious physical reactions due to certain triggers. These can range from a reaction to different medications, gaseous anaesthetics, caffeine, hops, and any activity level that is too demanding, or when the dog is stressed out; because of this last reason it is also nicknamed “canine stress syndrome”. Depending on the seriousness of Malignant Hyperthermia affecting your dog, the outlook ranges from fair to guarded, though with proper care and treatment, can be expected to return to a level of living that is comparable to before being affected. It can have a very sudden onset and can escalate quickly and proving fatal if not caught and treated promptly.
Symptoms of Malignant Hyperthermia in Dogs can develop quickly and these include: a sudden and dramatic increase of carbon dioxide, fever that elevates quickly and stays elevated up to 113F (45C), rapid heartbeat (tachycardia), rapid breathing (tachypnoea), cyanosis (the discoloration of skin due to low oxygen levels), rigid muscles, possible seizures, changes in blood pressure, fluid in the lungs, difficulty to form blood clots, Kidney failure, death.
Pyruvate Kinase (PK) is an enzyme that plays an important role in energy generation and its deficiency impairs the red blood cells’ (RBCs) ability to metabolize, which in turn may cause anaemia and other blood-related issues and is typically associated with a genetic defect acquired at birth. Symptoms usually begin to show around 4 months to 1 year if age and can include weakness, lack of energy, rapid heart rate, heart murmurs, pale gums, and stunted growth. As the disease progresses, bones and the liver can be affected, and the disease is ultimately fatal. It generally decreases the quality of life and may also decrease the life expectancy. Moderate severity that can cause significant signs of discomfort and/or dysfunction in affected animals and may involve relatively high treatment/management costs and can sometimes reduce life expectancy.
Dogs inheriting SD2 develop legs that are shorter than the recognized breed standard despite a normal sized body. Most commonly, front limbs are more severely affected than hind legs with this disorder. The ulna and radius bones of the front limbs may also be slightly more bent in comparison to normal dogs.
Penetrance meaning that not all dogs inheriting two copies (one from each parent) will display obvious physical characteristics of dwarfism.