Health Tests for Labrador Retrievers & Cocker Spaniels 

All Labrador Retrievers being used in a breeding program should have their hips and elbows tested for dysplasia and their eyes checked against genetic defect by a canine opthamologist.  However, there are other conditions that are found in Labs that should also be considered even though they may occur less frequently. 

Two Types of Tests

There are two basic types of health testing available to Labrador breeders. Both are important and the differences are explained below.

These are:

  1. Genetic Tests
  2. Phenotypic Tests

Genetic Testing

In order to understand genetic testing, it is helpful to have a little bit of a background in how genes are inherited. Here is a very brief explanation that you can use to help you more readily absorb the information about testing that will follow.

Every dog’s genetic material is made up of hundreds of thousands of genes. A gene is a sequence on a chromosome that codes for a specific trait, in whole or in part. A gene is made up of two parts  called ‘alleles’, which are special sequences of DNA.  For each gene, a dog gets one allele from each parent. For each trait, there may be several possible alleles, and because the dog gets one from each parent, he is potentially carrying two types of genetic material for each trait. In most cases one allele is ‘dominant’ over others. Alleles that are not expressed in the presence of a dominant allele are called ‘recessive’. Recessive alleles are only expressed if both are matching at that specific gene. If a dog inherits one dominant allele from parent A and a recessive allele from parent B, the dog will show the trait from parent A but is said to be a ‘carrier’ of the other allele. That is because they will pass that allele on to 50% of his own offspring. A dog who has two matching recessive alleles will express that trait and in the context of disease, is said to be ‘affected’.

In Labradors, there are several diseases that have been identified as the result of a specific mutation to a certain gene. These are usually inherited recessively- meaning that the ‘normal’ healthy allele is dominant to the mutant allele. So, a dog who has one normal copy and one mutated copy of the gene will appear normal, but could pass the mutated allele to offspring. If a puppy receives a mutated allele from BOTH parents, they will be affected and will show symptoms of the disease.

Genetic testing is important because for these conditions where a genetic mutation has been identified, it is possible to run a DNA test to determine if the dog is clear, carrier or affected. This allows breeders to plan matings so that NO puppies affected for that condition are born. That means that with appropriate testing and planning, there are several diseases that formerly were very common in Labs that can now be 100% prevented. A breeder doing proper testing can definitely guarantee that their puppies will not be affected by those diseases. For recessive diseases, it is not even that hard to plan ‘safe’ breedings- as long as one parent has been tested ‘clear’ for the disease in question, there is no possible way for the puppies to end up with that disease. So – as a puppy buyer- that means that you should ensure that any breeder you are considering has PROOF (test results) of at least one parent’s ‘clear’ status for genetic recessive diseases. It is NOT enough to see that both parents appear healthy because they could potentially each have a mutated allele that could be passed on to the puppies- testing is the only way to know for sure.

In Labradors, genetic tests are available for the following diseases:

  • prcd-PRA  , "Progressive Retinal Atrophy" is an inherited retinal atrophy that leads to blindness. Thanks to genetic testing, prcd-PRA is now very rare 
  • EIC,  "Excercise Induced Collapse" is a shortening of the dog's rear end that occurs as a result of heavy exertion and an accelerated state. The dog returns to normal after rest, but the attack may recur. There are quite a lot of "carriers" and "sick" dogs in the breed, but only some of the sick dogs get seizures.
  • RD/OSD,   "Oculoskeletal dysplasia" is a syndrome involving underdevelopment of the retina and skeletal development disorders.
  • CNM,  "Centronuclear Myopathy" is a severe muscle wasting disease that occurs in young dogs. So far, this disease has only been found in hunting dogs. 
  • HNPK,  "Hereditare Nasal Parakeratosis" is nasal parakeratosis, or more commonly known as dry keratoses. A sick dog's rind is dry and cracked. So far, HNPK has not been found in hunting dogs. 
  • MFD/SD2,  "Mild Form of Dwarfism" is a mild form of dwarfism found in hunting dogs. MFD dogs are small and short-limbed, especially the front legs may be shorter than normal. It is a structural characteristic rather than a disease, but testing dogs is considered desirable, so that "clubfootedness" and small size do not become common in the breed. So far, this disease has only been found in hunting dogs. 
  • STGD  , "Stargardt" is a new form of PRA (retinal degeneration) found in Labrador retrievers, which according to current information appears in older dogs, first as photophobia and later leads to blindness in the dog.

Phenotypic Testing

The other type of testing that is done is called ‘phenotypic’ testing. Phenotypic testing checks for outward signs of the disease.  and occurs for conditions that are believed or known to be heritable, but where the genes responsible have not yet been identified. Since DNA testing can’t be done, the next best thing is to thoroughly examine the parent dogs and avoid breeding dogs that have the signs/symptoms of the disease in question.  Breeders also use testing information to avoid breeding healthy dogs who have many relatives who show symptoms of the disease.

It has been proven that breeding dogs who are free of clinical OR subclinical signs of the following diseases helps reduce the odds of disease in the puppies, but cannot eliminate the chance completely. In some cases of these disease, it is known that environmental factors (nutrition, exercise, injury, etc) can cause the disease to appear so while this testing is important, it’s not a guarantee that the puppy will be healthy and each puppy owner needs to do their best to make sure they do not inadvertently cause symptoms to appear through poor management.

For all of these conditions, BOTH parents need to be tested free of disease-

 

  • Hip Dysplasia – Hips are x-rayed and films sent to specialists for evaluation and grading.

Hip joint growth disorder, or hip dysplasia, is the most well-known joint defect in dogs. It is a mutual incompatibility between the articular fossa and the articular pin due to a developmental disorder. The changes are examined with an X-ray, and the defect is classified on the FCI scale A - E, where A means a normal joint, B a borderline case, C mild, D moderate and E a severe growth disorder.

Because these films look at the actual bones of the dog, it is important for the dog to be done growing to get an accurate evaluation. 

 

  • Elbow Dysplasia .

Elbow dysplasia (ED) is the most common cause of front leg joint pain and lameness in large and giant dogs. Different forms of elbow joint growth disorder include fragmentation of the inner part of the coronoid (processus coronoideus), osteochondrosis of the inner part of the humeral condyle (condylus humeralis) and unattached elbow process (processus anconaeus). Incongruence of the elbow joint (incongruity of the joint surfaces) is considered an important cause of all the growth disorders mentioned above and is also counted as a growth disorder of the elbow joint.

The mechanisms of inheritance of elbow joint growth disorder are unclear. Inheritance is quantitative, i.e. it is affected by several different genes. One of these genes may be the so-called large effect gene. The type of growth disorder varies in different breeds, which suggests that the causes are different genes. Dysplasia of the elbow joint is more common in males, probably due to the greater weight of males and possibly also due to hormonal factors. According to the current understanding, hereditary factors play the biggest role in the development of elbow joint growth disorder, but environmental factors play a role in its manifestation. In other words, with optimal nutrition, it is possible to prevent the development of a growth disorder in an individual with a hereditary tendency to it.

In Labs, only dogs with normal- rated elbows are recommended for breeding.

 

  • Eye diseases – 

Dogs who are intended for breeding should have their eyes examined annually, or at minimum, within 12 months prior to breeding. Eyes are examined by a canine opthamologist and checked for cataracts, lens and retina irregularities, and any other sign of disease. Several types of eye diseases are believed to be heritable in Labs/Cockers but few have genetic tests available so having eyes examined helps identify issues as soon as they arise to eliminate affected dogs from breeding. 

 

MORE info on other health Issues are HERE Labradors    & Cockers Spaniels