Health Testing in Dogs Explained. A Guide for Puppy Buyers
Health testing in dogs can seem very confusing, especially for new puppy buyers. Adverts for puppies often included phrases such as 'health tested' when this is not the case, making things even more complicated.
To appreciate what health testing really means, it has to be understood why it is done and why a simple vet visit is not enough to consider a dog health tested.
At its most basic, health tests are designed to reduce or completely eliminate the chances of puppies developing life limiting or fatal health conditions. Before you buy a puppy, whether it is full pedigree or a cross, you should know all about the health problems within the breed and what health tests can be done to avoid them.
What is Health Testing in Dogs?
Health testing indicates that a puppy’s parents have been tested for conditions that are known to be an issue within the breed. For instance, hip dysplasia (HD) is prominent in Labrador retrievers (along with other breeds) and when choosing a Labrador puppy it is advisable to pick a breeder who has had their breeding dogs tested for hip dysplasia.
Some health tests are as simple as a DNA test where a swab of saliva is taken from a dog, sent to a laboratory and the result returned. Other tests require a physical examination by a specialist vet. Certain eye tests are done by certified veterinary ophthalmologists and need to be redone yearly. Others require x-rays - hip dysplasia (HD) and elbow dysplasia (ED) are tested for in this way - with the x-rays being sent to experts to assess them.
While some tests are universal across all breeds (all breeds should be checked for ED, HD and luxating patella) other tests are specific to a certain breed or breeds. You can find a full list of the DNA tests your chosen breed requires here. Breed clubs will usually list the relevant tests expected for their breed and will give you information on the health issues that are prevalent in that breed.
Health tests are there to determine if a dog has a genetic condition that could be inherited by a puppy and potentially shorten or reduce the quality of their life. Take for example the condition of Progressive Retinal Atrophy (PRA). PRA causes a dog to go blind, there is no cure. The condition can only be passed to a puppy if both parents carry the gene for PRA. If the parents have been tested for PRA and are clear of the gene, their puppies can never have PRA. While PRA is serious enough, other genetic conditions, such as Acral Mutilation Syndrome (AMS), can be devastating and result in a young dog having to be put to sleep.
The main bodies for recording and promoting health testing vary by country. In the UK the Kennel Club keeps records of health testing for dogs registered with them, while the British Veterinary Association (BVA) runs screening for hips, elbows and eyes. Other tests are performed through independent laboratories and the results registered with the Kennel Club.
In the US the Orthopedic Foundation for Animals (OFA) runs health screening and records the results of health test through their Canine Health Information Centre.
What Health Testing is Not
Health testing is not a routine examination by a vet before a puppy is taken on by a buyer. This might be considered a ‘health check’ to determine the puppy is healthy at that current moment in time, but a vet conducting a physical examination cannot determine if there is an underlying genetic condition that could impair your puppy’s quality of life in the future.
Each genuine health test a dog has will result in a certificate being issued by a recognised laboratory or specialist. These should be available for a prospective puppy buyer to view. If a breeder cannot present these certificates despite claiming dogs are health tested, then a buyer should be concerned whether these tests have ever been done.
Many DNA tests have the results automatically sent to the Kennel Club (UK) and you can check to see if a dog's tests are genuine using their Health Tests Results Finder. Results for eye tests and hips or elbow scoring may also be found using this search.
In the US, the OFA offers a similar service through their Canine Health Information Center
Do Crossbreeds Need to be Health Tested
There is a myth that crossbreeds are healthier than pedigree dogs. This is inaccurate. Many health conditions you find in pedigree dogs are found in crossbreeds too. One example is luxating patella (slipping kneecap), which is found in all dog breeds, but is particularly common in smaller breeds. Two breeds that often suffer from luxating patella are cocker spaniels and poodles. These are the same breeds that are bred together to produce cockapoos, a crossbreed that is increasing in popularity. As a result, Cockapoos are prone to luxating patella, inheriting it from their parent breeds.
Occasionally, some genetic conditions are exclusive to a particular breed and cannot be shared to any offspring that are a result of cross breeding. Take, for example, PRA. PRA is found in a number of breeds, but the gene that causes it is different for different breeds. Therefore a border collie affected by PRA could be bred to a poodle affected by PRA and the puppies would not be affected. They could carry the gene, but would not suffer the condition.
However, in poodles, spaniels and Labradors, the gene that causes PRA is the same. This means the gene originated back before these breeds were developed and they must have all shared a common ancestor at some point. If you breed a PRA affected poodle with a PRA affected Labrador, you will have puppies with PRA.
Confusing? It certainly is. But the simplest solution when buying a crossbreed, is to look for a breeder who health tests their parent dogs for the conditions prevalent in their respective breeds. Forget about ‘hybrid vigour’, crossbreeds can suffer from genetic illnesses too and health testing is just as important for them as a pedigree.
At a minimum, crossbreed parents should have been tested for hip dysplasia, elbow dysplasia and ideally luxating patella.
How is Health Testing Done?
There are two main types of health testing for dogs. There are physical tests where a dog is examined by an expert in a particular field (such as an ophthalmologist for eyes). Some of these tests require the dog to be sedated and x-rays taken, while others are conducted while the dog is conscious.
Then there are DNA tests, which are usually performed by the breeder. A breeder will collect a swab of saliva from a dog and this will be sent off to a specialist laboratory where the dogs DNA is tested to see if it carries any genes known to cause health issues. Understanding these different forms of testing is important to appreciate what you are being told by a breeder.
Below we examine these different forms of testing in detail.
Tests Using X-Rays - Hip and Elbow Dysplasia
X-rays for hip dysplasia and elbow dysplasia are normally taken by your own vet and then sent away to a specialist examination board (British Veterinary Association (BVA)) in the UK. Orthopedic Foundation for Animals (OFA) in the US. The dog's hips and elbows are assessed for deformities and the results given either a number or a grade to indicate the quality of the dog's joints.
Hip Scoring/Grades Explained
UK - A number between 0 and 53 is given to the dog’s hip joint. 0 indicates the hip has no abnormalities and is perfect. 53 indicates the dog has severe hip dysplasia. These numbers can be recorded individually for each hip (ie 0 - 5 would indicate that one hip was perfect and one hip had slight imperfections) or the two numbers combined to give a total score (ie. a dog with 13 - 20 hips could be scored as a total of 33). The lower the number the better. Most breeds in the UK have been given an average hip score and breeders aim to only breed from dogs with hip scores lower than the average. For instance, the breed average for Labrador retrievers (as of 2018) was 9, so only parents with hip scores lower than 9 should be bred from. While in the Otterhound, the breed average is 31, and dogs should only be bred if they have a hip score lower than this.
US - Hips are graded out of 7 categories (Excellent, Good, Fair, Borderline, Mild, Moderate, Severe). Only dogs with Fair, Good and Excellent graded hips should be used for breeding. Dogs in the Mild, Moderate and Severe categories, all show signs of hip dysplasia.
Other countries - there are numerous variations in the way hips are graded or scored in other countries. In parts of Europe the Federation Cynologique Internationale (FCI) is responsible for hip scoring and they use a letter system with hips graded A-E. A-1, A-2 and B-1 are equivalent to the US Excellent, Good, and Fair. B-2, C, D and E graded hips fall into the category of showing signs of dysplasia, with E being severe dysplasia.
Elbow dysplasia is scored differently. In the UK the elbow joint is given a score between 0 and 3, 0 being ideal. The US also uses a numerical evaluation for elbows, but calls them grades. A dog with normal elbows does not receive a grade, as these are only for dogs with ED. Grade I describes an elbow that shows on minimal changes, while Grade III is an elbow with significant changes.
Hip and elbow x-rays are usually only done once during the dog’s lifetime.
Physical Examinations - Luxating Patella
Luxating patella is the only test that is conducted purely through the manipulation of the dog to determine the condition of the knee. Dogs being tested are assessed by a vet with specialist knowledge usually with the dog non-sedated. Since dogs with luxating patella should not be bred from, a simple yes or no is all that is required concerning the dog’s knees.
Luxating patella can also be graded from 0-4. Grades 3 & 4 are usually so severe the dog is unable to walk normally. Grading is not as important for health tests however, as only dogs with a ‘clear’ result to their examination (no luxation of the patella) should be used for breeding. There is no official Kennel Club (UK) testing scheme for luxating patella, so screening is organised through breed clubs. In the US, screening is available through the OFA.
Specialist eye examinations are necessary in breeding dogs to determine the quality of their vision and to pick up early signs of eye problems they could pass on to puppies. These are conducted at eye screening clinics by veterinary ophthalmologists. They need to be done every year and the dog owner receives a certificate to confirm the dog’s eyes have been deemed normal.
In the UK, eye tests are conducted through the BVA (British Veterinary Association) Eye Schemeand in the US they are run by the OFA under the Companion Animal Eye Registry (CAER).
The BVA eye scheme looks for the following conditions that are hereditary (can be passed from parent to puppy) and are present from birth -
(CEA) Collie Eye Anomaly
(MRD) Multifocal Retinal Dysplasia
(TRD) Total Retinal Dysplasia
(CHC) Congenital Hereditary Cataract
(PHPV) Persistent Hyperplastic Primary Vitreous
(PLA) Pectinate Ligament Abnormality
They also look for other hereditary defects in the eye that do not develop until later in life, these are -
(HC) Hereditary Cataract
(PLL) Primary Lens Luxation
(POAG) Primary open angle Glaucoma
(PRA) Progressive Retinal Atrophy
(REPD) Retinal Pigment Epithelial Dystrophy
It should be noted that some of these conditions can also be tested for via a DNA test to ensure the dog does not carry the gene for it (see below), however, the BVA recommends doing this in conjunction with their scheme for the fullest picture of a dog’s health.
The Brainstem Auditory Evoke Response test (BAER) is a simple test used to determine a dog’s range of hearing. The electrical activity of the brain is monitored in response to various clicks to see how the dog responds. This non-invasive test can easily show if a dog is deaf and how severe the deafness may be. Certain breeds are at a greater risk of congenital deafness (for instance dalmatians) and breeders like to have their puppies' hearing tested before they are sent to their new homes, as deafness can impact on a dog’s training and lifestyle.
It is not so common for dogs to be tested before being breed. However, the Animal Health Trust advises having parent dogs BAER tested to reduce the risk of their puppies being partially or fully deaf.
DNA testing for genetic diseases in dogs has emerged in the last decade mainly due to the pioneering work of the Animal Health Trust who were the first to map the canine genome. Their ongoing work has enabled numerous tests to become available to breeders to enable them to ensure their breeding dogs are not going to pass deadly diseases to their offspring.
DNA tests are carried out by taking a swab from a dog’s mouth. This is sent off to a laboratory to be processed. The results of the test will inform the breeder if their dog is clear (does not carry the gene for a disease), a carrier (carries one copy of a bad gene) or is affected by a certain genetic disorder.
Inherited conditions are passed to a puppy when both parents carry the gene for the condition. Puppies inherit a copy of a gene from each parent, these genes can be good or bad. Fortunately, bad genes only cause a problem when a puppy inherits two copies, one from its father and one from its mother. Take, for example, the MRD1 gene, which causes affected dogs to react badly to routine vaccinations, certain anaesthetics, drugs and flea treatments. This can lead to fatal consequences. For a puppy to be affected by MRD1, it must have two copies of the gene, one from each parent. If only one of its parents carried the gene, it could not be affected by MRD1.
Let’s break that down further. A dog that does not have a copy of the MRD1 gene in its DNA is considered ‘clear’. It neither carries the disease nor is affected by it. It therefore cannot pass the gene to its puppies.
A dog that has one copy of the MRD1 gene is called a ‘carrier’. It is not affected by the condition, but it could pass a single copy of the gene to its puppies.
A dog with two copies of the MRD1 gene will be affected by the condition and will always pass the gene to its puppies.
Breeding two ‘clear’ dogs together will result in puppies that are also clear for MDR1 (this is sometimes called hereditary clear when breeders list health testing for a dog, meaning both its parents were clear of the condition)
Breeding a clear dog to a carrier, will result in some pups being clear and some pups being carriers for the condition, but none of the puppies will be affected by MDR1.
Breeding two carrier dogs together will result in some puppies being clear, some being carriers and some being affected by the condition.
Breeding two affected dogs together will result in all the puppies being affected by MDR1.
That might still sound confusing, but what a puppy buyer really needs to know is this - puppies should never be bred from two affected dogs or from an affected dog and a carrier. An ideal pairing is a clear dog to a clear dog, but this is not always possible as in some breeds there are not enough clear dogs, therefore good breeders will aim to produce puppies from a clear dog and a carrier. This will produce some pups that are clear and some pups that are carriers. Over time, detrimental genes can be removed from a breed by careful, selective breeding this way.
It would be a very unusual situation for an affected dog to be bred from. This would only apply in breeds that have a very small population number, in most popular breeds there is simply no reason to breed from an affected dog.
How Do I Know Which Tests my Pup's Parents Should Have?
While there are some health tests all breeding dogs should have (hip scoring and elbow scoring, tests for luxating patella, eye examinations), other tests are breed specific. Breed clubs will usually list the tests specific to that breed, so if, for instance, you looked up the breed club for Australian Shepherds, you should find a page that details health conditions found in the breed that need to be tested for.
You can also look up the health tests available for a breed on DNA testing sites such as Pet Genetics Lab, which lists the DNA health tests relevant for various breeds. Or on the Kennel Club Health Test webpage (link above).
If you are looking at getting a crossbreed, you should look up the tests relevant to the parent breeds. In many instances, the health conditions for the two breeds will be completely different and thus are not of concern, (unless you plan to breed your puppy eventually, in which case you should know if the parents are carriers for any conditions). Occasionally there will be conditions that are found in both breeds and should be tested for to ensure the puppies are not affected.
How Do I Know if a Dog's Health Tests are Genuine?
The hardest part for buyers is knowing if the breeder of their puppy is being honest about the health testing of their dogs. Each health test results in a certificate being generated that details what the dog was tested for and the result. Copies of these certificates should be available for a buyer to view, though of course they can be forged.
Results of health testing are submitted to the Kennel Club (UK) and puppy buyers can look up these results on the Health Tests Result Finder (links above). The OFA in the US runs a similar scheme called the Canine Health Information Centre (CHIC) Certification Program.
As a general guide, if the breeder is willing to show you certificates and the paperwork appears in order, there is a good probability the results are genuine. Puppy farmers and unscrupulous breeders will make excuses why you cannot see a certificate (they may say the same about pedigree papers), they may even inform you that their dogs are healthy and don’t need testing. If you hear this, do not purchase from that breeder!
As confusing as health testing might sound, becoming familiar with it and picking a puppy from health tested parents is the best way to ensure you have many happy, healthy years with your new canine buddy.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2020 Sophie Jackson