DNA tests

Whilst DNA tests cover a range of conditions, once you know how to think about one result - you know how to think about them all.  

Before we get into the separate conditions, let's look at the possible results and what they mean... 

DNA test results

There are three possible results of DNA tests:  

  • Clear - The dog does not have that condition, and will not develop it.  Genetically, the dog has no trace of that condition.  A Clear dog will not pass on any genes for the condition concerned.
  • Affected - The dog has that condition, or will develop it.  The dog may not be showing clinical signs of the condition yet, but they will go on to develop it.  Genetically, they have it.  An Affected dog should never be bred from, because they will (statistically) produce a percentage of Affected puppies, regardless of what dog they are bred with.
  • Carrier - The dog does not have that condition, and will not develop it.  But, genetically, they are a 'carrier' of it.  If a Carrier is bred to another Carrier (or to an Affected dog), there will be (statistically) some Affected puppies in the litter.  If a dog is a Carrier for a condition, they should only be bred to a Clear dog.  Then there will be no Affected puppies in the litter.

Should we avoid Carriers too?  Should they be eliminated from the gene pool? 

No.  It would be a bad idea to stop breeding from Carriers, because it would limit the gene pool greatly.  

Pedigree dogs already have restricted gene pools and we should not restrict those further by ruling out so many dogs.  

Instead, it is important to DNA test, so that we know if dogs are Carriers.  Then we can choose to breed Carriers only to Clear dogs.  This will ensure a broad gene pool is maintained, but also that no Affected puppies will be produced.

How are DNA tests carried out?

Whilst DNA tests can be run on blood, they are equally reliable when a dog's cheek is swabbed for saliva.  This means they are simple and easy tests which owners can carry out at home, without any vet involvement and with zero stress for the dog.

The owner contacts a laboratory offering the DNA test and orders a test kit for that condition, which contains cotton-wool swabs.  (We use Laboklin for most tests.)

The owner rubs the swab gently on the inside of the dog's cheek, to pick up skin cells there.  And then posts the swabs back to the lab.  

This is how easy it is, to take a DNA sample for testing. There is no reason for every labrador breeder not to be doing this!

What do DNA test results look like?

Test results are emailed direct to the owner about a week later.  

Here's an example of a DNA test report - click to enlarge and read:

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In summary, what DNA results do I look for?

Of course, you can only know whether a dog is a Carrier or (in many cases) an Affected, if they have been tested for the condition.  So the obvious thing to say is:  You need to ensure the breeder has actually done the tests!  

You are looking for:

EITHER:  

  • Clear.  Or Hereditary Clear.  (The latter means both the parents of the dog were tested Clear, so there was no need to do the test on the dog:  We know the dog is genetically a Clear.)

OR:

  • Carrier.  But, if one parent is a Carrier, make sure the other parent is a Clear.  A Carrier should only be bred to a Clear.  Then no puppies will have the condition.

So:  Which conditions should you expect a Labrador breeder to be DNA-testing for?

    prcd-PRA (Progressive retinal Atrophy)

    Progressive Retinal Atrophy, covers a group of eye-diseases which all lead to the retina degenerating over time, leading to eventual blindness.

    Prcd stands for progressive rod-cone degeneration, which is a type of PRA known to occur in Labradors (as well as in some other breeds).  So - this DNA test is not covering ALL types of PRA, only prcd-PRA.  Which is why the annual BVA eye exam is still essential.

    With the DNA test, we can easily test any dog, at any age - even before they have developed the condition - and we will know if they will go on to develop it, in future.

    This is important because clinical signs of prcd-PRA are not seen in BVA eye-tests until the dog is sometimes many years old.  

    Without the prcd-PRA DNA test, dogs affected by prcd-PRA would be bred from and pass on their genes - before anyone even knew they had prcd-PRA.    

      Dr Rowan Blogg, a specialist veterinary ophthalmologist, talks with Dr Noam Pik of ASAP laboratory about Progressive Retinal Atrophy, a disease causing blindness in many breeds of dog. What can be done to avoid this condition, and how do we go about it?

      Exercise Induced Collapse (EIC)

      Dogs affected with EIC suffer muscle-weakness, incoordination and collapse after just 5-15 minutes of strenuous exercise.  

      They cannot participate in any dog sport or work as gundogs, but must lead a very low-energy and sedate life to avoid a collapse.

      It is very distressing to watch a dog suffering from EIC, as their rear end becomes suddenly wobbly and unstable until eventually they fall to the ground.

      There is no cure or surgery for this condition.

      “This is right after about 10 minutes of playing fetch. Her back legs just give out and is seems that she cant really catch her breath.”

      Skeletal Dysplasia 2 (dwarfism)

      SD2 stands for Skeletal Dysplasia 2, which is a type of dwarfism affecting Labradors.

      Dogs affected with SD2 have extremely short legs, often looking like Basset Hounds.  Yet they have a normal-sized head and body.

      Although dogs affected by SD2 can lead a relatively normal and content life as a pet, they would not be able to be shown and they could not work in the field or participate in active dog sports.

      A puppy with SD2 looks normal when collected from a breeder at 8wks.  It is only when the puppy reaches 5-6 months that SD2 becomes apparent.

      There is no cure or surgery for this condition.

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      CentroNuclear Myopathy (CNM)

      CNM is a disease causing muscle wastage, which is completely debilitating.  The closest condition in humans is probably muscular dystrophy.  

      Movement for these dogs is difficult and it is impossible for the dog to lead a normal life.

      Onset of symptoms is between 8-20wks old.  This means that unsuspecting puppy buyers don't realise their pup has it, when collecting from the breeder.

      “This is Chico, also known as Chief. Chico is a Labrador, and at first glance he looks like the picture-perfect example of the breed. But unfortunately Chico is affected by a genetic disorder in purebred Labs called centronuclear myopathy (CNM).”

      “Butters, a yellow Labrador with CNM, drags herself along in an effort to keep up with her stronger siblings. Typically lacking impulse control, she would take a rest, but not a long enough one, before continuing on.”

      Hereditary nasal parakeratosis (hnpk)

      HNPK is a condition which sees the dog's nose dry out, leading to flaky skin and inflammation on the nose; crusts and scales; and sometimes painful cracks, which can get infected.  

      The nose often depigments from dark to light in colour and requires attention and medical care throughout the lifetime of the dog.  It looks very unsightly. 

      Symptoms first develop between 6-12 months of age, so puppy buyers would be unaware their puppy is affected when collecting from the breeder.

       

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      But there are loads of other dna tests available for labradors:  should dogs have all of these?

      Popular breed
      Labradors are one of the most popular breeds of dog, which means that there is a huge incentive for laboratories to develop DNA tests for them - since these tests are going to be purchased more often than tests for obscure breeds(!). 

      As a result, we have tests that have been developed for uncommon conditions.  For example, you can now test your Labrador for narcolepsy (falling asleep); achromatopsia (day blindness); Alexander disease; retinal dysplasia - and many, many more conditions.

      Confusion
      It can be hard to sort through all these tests to determine which ones a responsible breeder should do, and which ones are unnecessary and exist mainly to make money for laboratories.

      To muddy the waters further, some Labrador breeders use the existence of all these tests as a justification for not doing enough of them.  This is the 'oh, they are always developing new tests for things and most of them are pointless, therefore we can ignore most of them' mindset.

      Given that each test costs in the region of £85, you can see why unscrupulous breeders would choose to avoid them.

      Owners of widely used stud dogs can also be reluctant to test for new conditions - they don't want others to discover their dog has been unwittingly breeding Affected dogs.  This is the 'better not going poking and stirring' mentality!

      So which ones to do?
      There will never be an absolute and firmly recommended list which is unchanging.  

      It is important not to get stuck in a 'this is what I've always tested for, so I'm not testing for more than this' way of thinking.  Instead, acknowledge that new tests will be required... 

      We carry out the DNA tests listed above on this page.  We base this on the following:

      • The Kennel Club Assured Breeder list of tests (importantly not just the 'mandatory' tests, but also the 'strongly recommended' and the 'should also be considered' list)
      • Information about any conditions known in our lines, diagnosed or not
      • Being aware, via contact with other breeders and social media, of conditions in the breed

      As an example, when Moye had her 2016 litter, HNPK did not appear in the Assured Breeder list of tests (any of the three lists!) and the results for HNPK were not recorded by the KC in Mate Select.

      In 2018, we were within a year of her next breeding.  HNPK had since appeared in the Assured Breeder 'should also be considered' list and results are recorded in KC Mate Select - and so we have tested her for it.