Health testing:  One of the most widely used, yet most misunderstood terms in all of dogdom.  Breeders know they are supposed to do it; buyers know they are supposed to ask breeders about it; and most owners believe that it doesn't pertain to their dogs.  However, many do not really understand the ins and outs, or the how and why of health testing.  I am looking forward to bringing you a series of articles that will answer the questions about health testing that many do not even know to ask.

It is a common misconception that "health testing" consists of a breeder simply performing a short series of predetermined tests on both the sire and the dam, and checking off the list as they receive normal results.  Those two dogs can then be bred together and the resulting puppy owners can be assured that their puppy will be healthy and happy for life.  Sounds easy enough, right?  Wrong.  Let me explain...

There are different types of health tests available for dogs.  The first type of test, which is gaining widespread recognition, is genetic testing, often referred to as DNA testing.  These tests are looking at the dog's genetic code to find mutations that may lead to disease.  Common examples in dogs would be degenerative myelopathy (DM), multi-drug resistance (MDR1) and progressive retinal atrophy (PRA).  These tests are, for the most part, definitive tests that will tell you whether the dog is clear of the mutation or carries one or two mutated copies of the allele.  The significance of these results is dependent on the mode of inheritance for each particular disease.

The second, and most widely recognized, type of tests are phenotypic evaluations.  These include x-rays for hip and elbow dysplasia, ophthalmologic exam of the eyes, auscultation of the heart, blood tests for autoimmune thyroiditis, along with many others.  These tests are looking for clinical evidence of disease in the dog.  Only dogs that are affected with these diseases will show up as abnormal on these tests.  Although phenotypic evaluations are important to help reduce the prevalence of disease in our breed, they are not able to tell you with certainty if the dog will produce these diseases in their offspring.  Most people think of these tests as "one and done".  Just get the test done and check it off the list.  Unfortunately, it isn't quite that straight forward.  Some of these tests need to be done every year and some health conditions do not present themselves until later in the dog's life.

There is yet another category of phenotypic evaluations that is often overlooked.  This includes conformation analysis, behavioral health assessment and allergies along with other skin conditions.  These are items that are not typically noted in health testing results, but are very much genetic in nature and should be equally of concern to breeders and buyers alike.  They can be among the most expensive and debilitating of health conditions.

There is also a large gap between the number of known disorders and the number of tests available.  Saying that a dog is "fully health tested" can be very misleading.  The notion that any dog can be tested clear of every possible disorder is unrealistic. 

DNA Tests

I would like to bring our focus back to genetic health testing.  It is important to note that DNA tests for health differ from the DNA profiling that is done by various kennel clubs for the purpose of determining parentage in offspring.  If an owner lists "DNA" on a dog's resume, do not assume that this means the dog has genetic health screenings done.  Be sure to ask for copies of any health test results.  There are over 220 available genetic health tests for dogs currently available.  The vast majority of these are breed specific and do not apply to the Dutch shepherd.  However, there are a few diseases that warrant the breed fancier's attention.  These include Degenerative Myelopathy, Spongy Degeneration with Cerebellar Ataxia 1 & 2 and Inflammatory Myopathy.

Degenerative Myelopathy (DM) is a neurologic disorder in dogs that is the equivalent of amyotrophic lateral sclerosis (Lou Gehrig's Disease) in humans.  The average age of onset for dogs affected by DM is nine years old.  The initial presentation of the disease is gradual muscle atrophy and loss of coordination that typically begins in the hind limbs due to nerve degeneration.  The condition is not painful but will continue to progress until the dog is no longer able to walk.  This will typically occur within 6 months to 2 years from onset of symptoms.  In late stages of the disease, fecal and urinary incontinence may occur, and the forelimbs may be affected.  The only way to definitively diagnose DM is through microscopic analysis of the spinal cord after death.  There is no cure and treatment is focused on keeping the dog comfortable.  Degenerative myelopathy is caused by mutations in the SOD1 gene.  The inheritance is recessive with incomplete penetrance.  This means that, while dogs with two copies of the mutation are at much greater risk of developing the disease compared to those with only one or zero copies of the mutation, not every dog that has inherited the genetic mutations will develop the disease.  It is believed that other genetic and/or environmental factors may modify the expression of DM.

Spongy Degeneration with Cerebellar Ataxia 1 & 2 (SDCA1, SDCA2) are neurodegenerative conditions that were first described in the Belgian malinois.  SDCA1 is caused by mutations in the KCNJ10 gene while mutations in the ATP1B2 gene are responsible for causing SDCA2.  Both diseases are inherited in an autosomal recessive manner.  This means that a dog must have two copies of the mutation in order to develop clinical signs.  The presentation of both SDCA1 and SDCA2 is the same.  Affected puppies display symptoms between 4.5 and 8.5 weeks of age.  They will have a wide-based ataxic gait which is more prominent in the hind limbs and accompanied with stumbling, staggering, tremors, bunny-hopping, loss of balance and falling.  Affected puppies may also develop seizures and are often euthanized due to the severity of symptoms.  Since puppies often show clinical signs before they would be old enough to go to new homes, SDCA1 & 2 are diseases that should be of most concern to breeders.  When breeding two carriers of the mutated genes together, each pup has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier and a 25% of being unaffected and not being a carrier.  There is no cure for either form of Spongy Degeneration with Cerebellar Ataxia.

Inflammatory Myopathy (IM) is a genetic disease that is currently specific to the Dutch shepherd.  The condition presents with muscle tremors, pelvic limb stiffness, progressive weakness and severe muscle atrophy  at 3-9 months of age.  All affected dogs have been euthanized prior to 2 years old due to the severity of symptoms.  There is no known treatment for the disease.  IM is caused by a mutation at the SLC25A12 gene and the mode of inheritance is autosomal recessive.  Therefore, affected dogs must have two copies of the mutation to show clinical signs.

Two other diseases, von Willebrands and Mucopolysaccharidosis VII, have also shown up in genetic testing of Dutch shepherds.  The prevalence in the breed is currently unknown, but it is worth breed fanciers taking note and being aware of future concerns in regards to these diseases.

Genetic health screenings are among the easiest and least expensive of all health tests.  Testing kits can be ordered through a variety of labs online and will be delivered to your home.  The kits contain buccal (cheek) swabs that you can use to take samples at home and then mail back to the lab.  Testing is available for each individual disease for as low as $40.  However, the best bang for your buck comes from ordering complete DNA test kits that include health and trait testing as well as Coefficient of Inbreeding (COI) to measure genetic diversity.  One such company that offers complete testing is Embark.  Embark's test kit includes all of the above mentioned diseases  as well as trait testing  that is applicable to our breed, such as dilute (blue), long coat and hind dewclaws, all for one price. 

I want to stress the importance of using genetic health screening as just a tool that is available in our toolbox to be used to breed healthier dogs.   It is easy to jump to the conclusion that all affected and carrier dogs must be removed from breeding.  Unfortunately, that solution will only open a Pandora's box of other problems.  DNA tests are only available for a fraction of known disorders.  We need to be careful to guard against reducing the number of dogs carrying or affected by a disorder we can test for only to increase the number affected by a currently more rare disorder.  It is a better strategy to be cautious of overusing popular sires, inbreeding and breeding for very specific traits.  This will help to increase genetic diversity and thereby reduce the chances that two unknown or rare defective genes will come together.  This is not to say that we should not be utilizing the available tests.  Rather, we must use them in combination with other appropriate breeding strategies. 

Phenotypic Evaluations

While genetic tests can offer direct information to owners and breeders about disease causing genes that a particular dog carries that can affect the dog itself as well as the dog's offspring, unfortunately, they are currently only available for a small number of known conditions.  The rest of the testing available to owners and breeders are known as phenotypic evaluations. 

Phenotype, with the root "pheno", which means "observe", refers to the observable characteristics of an organism.  Most health testing in the Dutch Shepherd is done by observing the dog's current physical status.  When attempting to reduce the incidence of disease presentation, testing for these conditions is far from straight forward.   Breeders and buyers alike must understand that many undesirable genes may not present as detectable disease during the peak breeding years of a dog's life, if ever.  Dogs that appear normal may, in fact, be carrying genes capable of causing disease.  Lending to this confusion may be conditions that have multiple gene involvement, any environmental influence on the condition and diseases that have a late age of onset.  When dealing with conditions that rely on a phenotypic evaluation for diagnosis, it is crucial to not only look at the dog before you, but to also look at the results of siblings, parents, parents' siblings, grandparents and the grandparents' siblings as well.  The more data you have, the more complete picture you will be able to obtain on what genetic predispositions your dog may have.  Even if you have no interest in breeding your own dog, their health testing results play an important part in the future of our breed by providing valuable information for breeders.

Canine Hip Dysplasia (CHD)

When addressing phenotypic evaluations, the obvious place to start is with a condition that is familiar to most - canine hip dysplasia (CHD).  CHD is commonly recognized as a deformity of the hip that occurs during growth due to a lack of depth of the ball and socket joint, laxity in the joint, or a combination of the two.  The cause of these anatomic abnormalities is multifactorial.  Genetics, diet, environment, exercise, growth rate, muscle mass and hormones can all play a part in the development of the disease.  It is often mistakenly proclaimed that testing is not necessary because a particular dog has never shown any signs of hip problems.  Severity of symptoms of CHD do not necessarily correlate to the severity of disease and many dogs with CHD do not display outward symptoms.  The only way to truly know the health status of the hips in a dog is through radiographic evaluation. In the USA, there are two main options for obtaining official evaluations for hips.

The most widely recognized hip evaluation is done through Orthopedic Foundation for Animals (OFA).  OFA requires one radiograph (x-ray) to be taken of the dog's hips in an extended position.  Dogs may be sedated for the procedure, but it is not required, and any veterinarian is able to submit radiographs to OFA.  When a hip radiograph is submitted to the OFA, board certified veterinary radiologists provide a subjective review of the radiograph based on nine different anatomic areas of the hip and they are given one of seven "grades".  These grades are Excellent, Good, Fair (all of which are considered within normal limits), Borderline, and Mild, Moderate, or Severe (the last three are considered dysplastic).  In order to obtain a final evaluation grade with OFA, dogs must be 24 months or older and the radiograph is evaluated by three radiologists.  Each radiologist gives an independent grade and the final grade is decided by a consensus of the three evaluations.  Normal results will be posted on a public database located on OFA's website, while abnormal results are only posted publicly if the owner initials the application allowing the OFA to release those results.  Preliminary results may be obtained between 4-23 months after evaluation by one radiologist, but results, whether normal or abnormal, will only be made public if the dog is over 12 months and the owner has initialed the box allowing results to be made public.  The reliability of preliminary evaluations increases as the age at the time of the evaluation increases.  Since there is no special certification required for a veterinarian to submit a radiograph, it is easy to locate a vet that will do the procedure.  However, this also means that the veterinarian may not be well versed in performing the procedure and the positioning of the dog and the quality of the radiograph may be compromised and affect the result of the grade obtained.  While the requirement for only one radiograph and sedation being optional makes OFA testing an economical choice, it also gives a limited amount of information and allows for more manipulation of the picture obtained in the radiograph.  Turnaround time for evaluations is approximately 2-3 weeks from the time the application and radiograph arrives at OFA. 

ANTECH Imaging Services (AIS) also offers official hip evaluation, through the PennHip method, that is gaining more recognition each year.  PennHip testing requires a series of three different radiographs (compression view, distraction view, and hip extended view) to be submitted.  It is required that: the dog be heavily sedated; the procedure is performed by a veterinarian that is specially trained and certified; and specific equipment be used.  The radiograph is submitted by the veterinarian and evaluated by a board certified veterinary radiologist for an objective, rather than subjective, evaluation of the distraction index (DI) for each hip joint.  The DI is a measure of hip laxity and is expressed as a number between zero and one.  A DI near zero indicates very tight hips with little joint laxity while a DI closer to 1.0 is indicative of very loose hips with a high degree of laxity.  Since joint laxity is a primary indicator for the future development of hip dysplasia, dogs with tighter hips are less likely to develop CHD than those with looser hips.  The hip extended view is also evaluated for the presence of arthritic changes that may confirm a current diagnosis of CHD.  PennHip evaluations are deemed to be accurate from 16 weeks old, allowing dogs with dysplastic hips to be identified earlier.  This opens the door for interventional procedures to be performed and breeders to make earlier decisions regarding their breeding stock.  It can be difficult to locate a local veterinarian that has the training and certification required to perform the PennHip procedure, although AIS has a veterinarian locator on their website to help with the search.  The requirement for sedation and multiple radiographic views increases the cost for the procedure, making it a less affordable option.  The veterinarian performing the procedure will be issued a written evaluation report and you can obtain a copy of the report from the veterinarian. There is currently no public database for dogs that have received evaluations through AIS.  OFA offers the option of submitting the PennHip evaluation report for posting on their public database for a fee.  However, breeders or sellers should be able to produce a copy of the evaluation report for viewing by interested parties. Turnaround time for evaluation results is typically 72 hours.

People will often ask which evaluation is "better".  As you can see, the evaluation procedures are quite different and each have their own pros and cons.  For those wanting the most complete picture of hip health, the choice may be made to have both evaluations performed.  Regardless of what choice you decide is right for you and your dog, sharing the results with others will help everyone to make better informed decisions for the future of CHD in the Dutch shepherd. 

Elbow Dysplasia

Widely recognized, but less commonly understood, phenotypic evaluations for elbow dysplasia (ED) are equally as important as CHD.  Elbow dysplasia is an umbrella term that covers a number of different conditions in the joint that are consequences of the abnormal development in how the humerus, radius and ulna bones fit together.   These conditions include:  Fragmented medial coronoid process (FCP); Osteochondritis dissecans (OCD);  and Ununited anconeal process (UAP).  Any one of these conditions will lead to a diagnosis of ED, but a dog may have more than one of these occur in the same joint simultaneously. Each of these etiologies has shown to have inherited polygenic (involving multiple genes) traits that may or may not be independent of one another.  Currently, the only official evaluation that can be done for elbows in the USA is through the OFA.  The OFA requires a single extreme flexed medial-lateral view of each elbow to be submitted by a veterinarian, with sedation being optional.  Just as with hips, the radiographs are reviewed by board certified veterinary radiologists and given a grade.  For elbows that show no evidence of disease, they are rated as Normal.  Abnormal elbows are graded with either Grade I, II or III elbow dysplasia.  Often, only "DJD" (degenerative joint disease) is marked on the results.  DJD is a result of ED, so when only DJD is marked on the report, it can be assumed that lesions associated with coronoid process disease are present.  It is important to note that no evidence of disease on the radiograph of a symptomatic dog is not conclusive of normal elbows.  While UAP can usually be confirmed via a single radiograph, the other conditions are not so easily distinguished.  In these cases, additional radiographic views and/or a CT scan should be performed to rule out dysplasia.  Requirements for elbows, regarding age and posting on the public database, follow the same policies as hips for both preliminary and final evaluations.  Some veterinarians will offer a reduced rate when having both hips and elbow radiographs done at the same time and OFA offers a reduced fee when they are submitted together.

Eye Testing (Ophthalmologic Exam)

Another important phenotypic evaluation for Dutch Shepherds is a comprehensive ophthalmologic examination performed by a board-certified veterinary ophthalmologist. This examination screens for inherited eye disorders that may not be visible to the general practitioner during a routine physical exam.

In the Dutch Shepherd, inherited eye disorders have been noted, in particular, immune-mediated ocular disease, especially Chronic Superficial Keratitis (Pannus). Other conditions such as progressive retinal atrophy (PRA), cataracts, and retinal dysplasia can occur. Although DNA tests exist for some forms of PRA, not all types have a known genetic marker, making physical examination still necessary.

Pannus is an immune-mediated inflammatory condition that primarily affects the cornea, the clear surface of the eye. It leads to a progressive clouding and pigmentation of the cornea, which can severely impair vision over time. Pannus is thought to be triggered by environmental factors, such as UV light exposure, but it also has a clear genetic predisposition. The condition typically presents between 2 and 5 years of age and worsens with age. It is manageable with lifelong treatment, primarily through the use of topical corticosteroids or immunosuppressive medications, but it is not currently known to be curable. Early detection is key to preserving vision.

The examination is quick and painless, involving dilation of the dog's pupils to allow for evaluation of the lens, retina, optic nerve, and surrounding structures. Results can be submitted to the OFA for certification under the Companion Animal Eye Registry (CAER) program. Ophthalmologic exams should ideally be performed yearly until at least middle age. Buyers are encouraged to ask to see the most recent eye exam results, and to be aware that eye health, like all health testing, is just one piece of a much larger puzzle.

It is important for breeders to not only test their breeding animals but also to encourage pet owners to participate in eye exams. This helps the breed as a whole by tracking emerging issues that may not be visible immediately or in young dogs. Clear eye exams can provide additional assurance to puppy buyers and fellow breeders about the quality of your breeding program.

While not the only areas of concern, hip, elbow and eye phenotype evaluations constitute a good place to start for the health of our breed.  The median DI of the Dutch shepherd as of the end of 2021, per PennHip, is sitting at .37.  The current breed statistics per the OFA are 8.2% and 5.5% abnormal results for hips and elbows respectively.  We need to keep in mind that these percentages are determined by the radiographs that are actually received by OFA.  There are a certain number of radiographs and eye exams that will be obviously normal/abnormal when reviewed by the veterinarian performing the procedure and the owner may choose to not submit them for official evaluation where they would be included in these statistics.  Through transparency, open communication and educated breeding decisions, breed fanciers can work together to continue working the Dutch shepherd for generations to come.

Ever wondered about the genetics behind the Dutch Shepherd’s brindle color?