Labrador Health
Anyone interested in owning or breeding a Labrador Retriever should become familiar with the various medical conditions, and appropriate health clearances, before deciding to obtain a Labrador. The following are some of the more common health issues in the Labrador Retriever breed:
Hip and Elbow Dysplasia
Almost certainly you would have heard of hip dysplasia in large breed dogs, and unfortunately the labrador is no exception. Whilst the labrador is generally healthy and well-constructed, with strong well-proportioned bodies, hip and elbow dysplasia can occur. Two known factors determine whether hip dysplasia will occur and if so, how bad it will be. These are hereditary (genetic) and environmental influences. It is important you have knowledge about dysplasia, so that you are fully informed, can interpret your puppy’s parent’s hip and elbow scores, and understand disposition to dysplasia.
Dysplasia presents in dogs as instability of the hip joint (or elbow joint). In a normal hip, the femur is connected to the hip joint with the head of the femur (ball) sitting in the acetabulum (socket). In dogs who develop dysplasia, the ‘ball’ doesn’t fit as well in the socket as it should, resulting in joint laxity (looseness). Because the ligaments become overstretched by the looseness (causing the ball and socket to grind against one another rather than sliding smoothly), the joint attempts to re-establish stability by laying down new bone, creating spurs and scar tissue. This, coupled with the degeneration of cartilage (wear from rubbing), is what eventually causes lameness and painful osteoarthritis of the joint.
Eye Exams
Eye certification is one of the phenotypical evaluations that are registrable with the Orthopedic Foundation for Animals (OFA) through its Companion Animal Eye Registry (CAER). Most eye diseases are presumed hereditary. Many of them occur later in a dog’s life. This test can be performed at the vet’s office, during an eye clinic, or at health clinics hosted by kennel clubs around the country. The American College of Veterinary Ophthalmologists (AVCO) can also help you find a board-certified ophthalmologist in your area to conduct the test. It’s important to note that this exam is not a comprehensive ocular health examination. It is an eye screening exam. OFA recommends annual screening for breeding animals. OFA CAER Certification is for a 12-month period.
Tricuspid Valve Dysplasia (TVD)
The tricuspid valve pumps blood on the right side of the heart from the atrium into the ventricle. Labrador Retrievers with tricuspid valve dysplasia (TVD) have a valve that does not function properly and allows blood to leak backward into the right atrium. Over time, the right atrium and right ventricle become enlarged.
Labrador Retrievers with TVD may or may not have a heart murmur that can be heard during a routine physical exam. They can be asymptomatic or show signs of right-sided heart failure, which include: coughing, fluid in abdomen, difficulty breathing, rapid heart rate.
To reduce the occurrence of TVD in future progeny, dogs being used for breeding who come from lines with higher risk for TVD should be screened by echocardiogram to be free of TVD prior to breeding.
Diagnose TVD. Echocardiogram (ultrasound) is the preferred method for diagnosing TVD. By this method, adhesion of the tricuspid valve to the ventricular wall is easily visualized and allows a definitive diagnosis. Electrocardiography (EKG) and radiography (X-Rays) are other methods for diagnosing TVD. Labrador retrievers with TVD frequently have atrial arrythmias, abnormalities of the heart beat, associated with the enlargement of the atrium which can be detected by EKG. Additionally, x-rays usually clearly demonstrate right-sided enlargement of the heart.
Understanding The Basic Science of Genetics Testing
When we talk about genetic diseases in Labs, it’s also important to understand a top-line view of the science behind genetics.
Genetic traits, including those that cause disease, are found to be either dominant or recessive.
Dominant Genes: If any diseases are found on dominant genes, they will only need one gene to show up in the puppies for the problem to develop.
Recessive Genes: Diseases from recessive genes need both parents to carry the genes and pass them to their offspring before the issues develop.
Dogs with only recessive genes from one parent are carriers, but they don’t demonstrate the illness. However, carriers will pass on their recessive genes 50% of the time, so two carriers bred together would result in a possible 25% of pups affected with the illness or disorder.
Genetic Tests recommended for Labradors include EIC, HNPK, PRA-prcd, CM, DM, Stargardt Disease, Copper Toxicosis, and MCD.
Exercise Induced Collapse (EIC)
EIC has been being tested for a while in labradors.
EIC is an autosomal recessive genetic disorder causing affected dogs to experience a collapse during or after extreme exercise. Typically an affected dog starts to manifest the disorder around five months to three years of age. Not all types of exercise can induce an attack: the dog generally would be actively running or excited for an extended period of time.
Because EIC is a recessive disorder, a dog must have two copies of the muted gene in order for the disease to manifest. This means a dog can have one copy of the mutation and not experience EIC, but would be considered a carrier. Dogs with EIC can still lead full lives. However, its important to be familiar with what types of activities trigger an episode.
Hereditary Nasal Parakeratosis / Dry Nose (HNPK)
HNPK is an inherited skin disorder that affects labradors. It is characterized by the development of dry skin and crusting on the nose, that can lead to cracked skin, fissures, and chronic inflammation of the skin on the nose. Generally parakeratosis is a benign skin condition. It is not physically contagious.
Progressive Rod Cone Disease (PRA-prcd)
PRA-prcd is a group of degenerative eye disorders causing blindness in both eyes over time. As its name implies, this blindness is caused by the gradual deterioration and loss of function in the retina and its photoreceptors: rods and cones. The membranous retina lines the back of the eyes and absorbs, reflects, and perceives light. A dog affected by PRA-prcd therefore loses his ability to see clearly as the membrane deteriorates.PRA-prcd is a late onset, inherited eye disease affecting Labrador Retrievers. It occurs as a result of degeneration of both rod and cone type Photoreceptor Cells of the Retina, which are important for vision in dim and bright light, respectively. Evidence of retinal disease in affected Labrador Retrievers can first be seen on an Electroretinogram around 1.5 years of age, but most affected dogs will not show signs of vision loss until 4 to 6 years of age or later. The rod type cells are affected first and affected dogs will initially have vision deficits in dim light (night blindness) and loss of peripheral vision. Over time affected dogs continue to lose night vision and begin to show visual deficits in bright light. Other signs of progressive retinal atrophy involve changes in reflectivity and appearance of a structure behind the retina called the Tapetum that can be observed on a veterinary eye exam. Although there is individual and breed variation in the age of onset and the rate of disease progression, the disease eventually progresses to complete blindness in most dogs.
Centronuclear Myopathy
Centronuclear myopathy (CNM) is a rare congenital disease that affects the skeletal muscle. With this condition, reflexes in the hind limbs become impaired.
Clinical signs include an abnormal gait and the inability to perform physical exercise, like go on a walk or run. The muscles become weak, especially in colder climates. Usually, symptoms first arise in Labradors at 2-5 months of age. By age 1, the dog’s head, neck, and leg muscles generally become atrophied, which causes weakness and continued gait issues. The condition tends to become stable after 1 year of age.
A muscle biopsy is needed to diagnose this condition. Genetic therapy is the treatment of choice. DNA testing is available to determine if a Labrador Retriever carries the genetic mutation for CNM. Reputable breeders will have their dogs tested and will not breed those that have the genetic mutation.
Degenerative Myelopathy (DM)
Degenerative Myelopathy is an inherited neurologic disorder caused by a Mutation of the SOD1 gene known to be carried by Labrador Retrievers. This mutation is found in many breeds of dog, though it is not clear for Labrador retrievers whether all dogs carrying two copies of the mutation will develop the disease. The variable presentation between breeds suggests that there are environmental or other genetic factors responsible for modifying disease expression. The average age of onset for dogs with degenerative myelopathy is approximately nine years of age. The disease affects the White Matter tissue of the spinal cord and is considered the canine equivalent to amyotrophic lateral sclerosis (Lou Gehrig’s disease) found in humans. Affected dogs usually present in adulthood with gradual muscle Atrophy and loss of coordination typically beginning in the hind limbs due to degeneration of the nerves. The condition is not typically painful for the dog, but will progress until the dog is no longer able to walk. The gait of dogs affected with degenerative myelopathy can be difficult to distinguish from the gait of dogs with hip dysplasia, arthritis of other joints of the hind limbs, or intervertebral disc disease. Late in the progression of disease, dogs may lose fecal and urinary continence and the forelimbs may be affected. Affected dogs may fully lose the ability to walk 6 months to 2 years after the onset of symptoms. Affected medium to large breed dogs, such as the Labrador retriever, can be difficult to manage and owners often elect euthanasia when their dog can no longer support weight in the hind limbs.
Stargardt Disease
Stargardt disease is an inherited eye disease affecting dogs. Stargardt disease is caused by the degeneration of both Rod and cone type Photoreceptor Cells of the Retina. These are important for vision in dim and bright light, respectively. Affected dogs present prior to 10 years of age with signs of vision loss including dilated pupils and decreased response to light. On a veterinary eye exam, affected dogs will have changes in reflectivity and appearance of a structure behind the retina called the Tapetum and, may show thinning of the retinal blood vessels. Dogs may not completely lose their vision during their lifetime, but will develop significant loss of vision, especially in well-lit environments.
Copper Toxicosis
Copper toxicosis (Labrador Retriever type) is an inherited metabolic disease affecting dogs, resulting in chronic liver failure. Dogs with copper toxicosis have a decreased ability to excrete dietary copper from the body resulting in excessive copper storage in tissues and organs, including the liver, which can result in liver damage and subsequent cirrhosis. Though the age of onset and speed of disease progression are variable, most affected dogs will present in middle age with non-specific signs of liver dysfunction including weight loss, lethargy, weakness, vomiting, diarrhea, and abdominal pain. In late stages of disease, affected dogs may develop signs of liver failure including abdominal swelling, jaundice, and neurological dysfunction. Dogs found to have one or two copies of the mutation may benefit from certain therapies.
Macular Corneal Dystrophy (MCD)
Macular corneal dystrophy is an inherited, progressive eye disease affecting dogs. Affected dogs frequently present around 4 to 6 years of age with clouding of their corneas accompanied by pinpoint white to gray spots made up of an accumulation of a carbohydrate known as glycosaminoglycan. Some affected dogs will also display growth of new blood vessels across the surface of their corneas. The disease will typically progress to compromise vision.