Health Testing

"What's the deal with health testing anyway?" - "Is it really that important?" - "Why should I bother testing if I know my dog is healthy?" - "I don't plan on breeding my dog, why should I care if his parents are tested?" All of these questions are valid, especially for the general pet owner who has never heard of the importance of health testing and what it is accomplishing throughout the dog world. 

According to The Kennel Club of the UK, "Testing all potential breeding stock, where relevant, allows breeders to determine the chance a dog may pass a disease causing gene on to its offspring, giving them the information required to avoid producing clinically affected puppies.1"

Many of the inherited diseases that affect dogs are a result of a mutation on a single gene, thus making it incredibly easy to predict their inheritance. Every puppy gets 50% of their DNA from each of their parents - so if both the dam and sire are clear of known inheritable diseases, it can be predicted with relative certainty that their offspring will be clear too. 

It gets a little more complicated when you start to consider the fact that some dogs are non-affected carriers of these diseases. This means that they inherited a bad copy of the gene from one of their parents and a good copy from the other. They aren't affected by the disease, but they are still able to pass on a copy of the bad gene to their progeny. This scenario is where DNA testing becomes the most important! If you didn't know that your dogs were carriers of the same disease and bred them together, there would be a 25% chance that they will produce puppies that are affected by the disease, and an additional 50% that they will pass along one bad copy of that gene, creating more carriers. By utilizing DNA testing, breeders are able to identify any disease carriers in their program, and can use that information to avoid producing affected puppies. 

graphic credit: Paw Print Genetics
This very basic lesson on genetics proves how vital it is for all breeders to be performing appropriate health testing on their dogs. With all of the advancements that have been made in modern medical technology, it is easier now than ever to get the testing done - there is no excuse for avoiding it. A single cheek swab can test a dog for a multitude of diseases, conditions, hidden coat colors, and so much more!

As a puppy buyer, it can be daunting to even know what health tests you should be asking your breeder about. Thankfully the OFA has developed a public database of recommended breed-specific testing which is a great place to start. 

OFA-CHIC Labrador Specific Testing Recommendations

  • Hip Dysplasia
  • Elbow Dysplasia
  • CAER Eye Exam
  • EIC (Exercise Induced Collapse) DNA Test
  • D Locus (Dilute) DNA Test (this is a color only test, it has no indication into the overall health of the dog)
  • CNM (Centronuclear Myopathy) DNA Test
  • Cardiac Evaluation
  • prcd-PRA (Progressive Retinal Atrophy) DNA Test

Breed-Specific or Full DNA Panel Tests

Many laboratories are now offering full DNA panels, or breed-specific DNA panels that test for multiple diseases at once. This has been a game changer for dog breeders, as not only can they test for the CHIC recommended diseases, they can also test for as many as 190+ genetic mutations

Other tests that are relevant for Labrador Retrievers include but are not limited to:
  • Congenital Macrothrombocytopenia
  • Degenerative Myelopathy (DM)
  • Hereditary Nasal Parakeratosis (HNPK)
  • Hyperuricosuria and Hyperuricemia or Urolithiasis (HUU)
  • Macular Corneal Dystrophy (MCD)
  • Narcolepsy
  • Retinal Dysplasia/Oculoskeletal Dysplasia 1 (RD/OSD1)
  • Pyruvate Kinase Deficiency (PKD)
  • Skeletal Dysplasia 2 (SD2)
  • Achromatopsia
  • Alexander Disease
  • Canine Elliptocytosis
  • Congenital Myasthenic Syndrome (CMS)
  • Golden Retriever Progressive Retinal Atrophy 2 (GR-PRA2)
  • Myotubular Myopathy 1, X-linked Myotubular Myopathy (XL-MTM)
  • Progressive Retinal Atrophy - crd4/cord1
  • Copper Toxicosis
  • Stargardt Disease

Hip Dysplasia

Hip dysplasia (HD) has been a topic of debate in the dog world for decades. In some of the earliest texts written about dogs, and more specifically Labrador Retrievers, HD is mentioned as a condition that should best be avoided by breeders. It was first believed to be a simple hereditary condition, and so by breeding only unaffected dogs, early breeders believed that they could control the incident of HD occurring in their puppies. However, HD is still a prevalent problem in many dog breeds, and so cannot be explained by something as simple as a recessive gene. 

Modern research has shown that puppies are all born with perfectly normal hips, as the cartilage making up their joints doesn't fully harden to bone until they have finished growing and their growth plates have closed. This means that if a puppy is going to develop HD, the process begins shortly after birth, before they even learn to walk! Research has also shown us just how much we don't yet know about the genes behind HD. Studies have been done and isolated some associated genes in various breeds, but they vary from breed to breed and are not truly the "cause" for the occurrence of HD. 

It is now commonly believed that over 50% of the cause of HD can be attributed to environmental factors such as joint laxity, weight, and exercise. Joint laxity occurs when the head of the femur does not sit snugly in the hip socket, thus creating a "loose" feel in the hip joint. This can lead to damage to the rim of the hip socket when weight is placed on the joint. This is why maintaining a healthy and appropriate weight on your puppy is such a critical factor to consider when trying to prevent the occurrence of HD. If left to become overweight, especially while developing, the weight that is placed on the puppy's hip joint is much greater than normal, causing a higher likelihood that damage could occur. Feeding their puppy a high quality food that provides all the nutrients they need, while keeping them from getting obese, is the number one thing a puppy owner can do to lessen the risk of HD in their puppy. The number two thing an owner can do to lessen the change of their puppy developing HD is to provide the correct amount and kind of age appropriate exercise that will not injure their joints. Puppies grow very quickly in their first year or so, which means their bones are soft and their growth plates haven't closed yet. This usually happens around the time a dog is fully grown (approximately 12-18 months, depending on the breed). Injuries to growth plates or joints in a puppy's early days can create a ripple effect that could potentially lead to more severe injuries, like HD, down the road.