Tag archives: genetic testing for dogs

Canine coat color and traits are determined by the interaction of multiple genes, each responsible for a specific inherited trait or characteristic. The development of genetic testing for these traits has resulted in a significant paradigm shift from historical breeding practices for the dog breeding community. With a few exceptions for colors or patterns that cannot yet be tested for, genetic coat color testing has eliminated the need to perform test breedings or to make assumptions when it comes to determining what coat colors and traits might be produced by a specific breeding pair.

Genetic Coat Color Testing Basics

Despite its power, the use of genetic testing does not eliminate the artistry of dog breeding or the advantages that come from experience. Instead, genetic testing assists in eliminating some of the challenges that biology presents. Regardless of a breeder’s experience level, colors or traits that are inherited in a recessive fashion can present significant challenges when it comes to predicting potential coat color breeding outcomes. Recessive traits are those that require a dog to inherit two copies of the associated genetic variant (one from each parent) in order to display that trait. The challenge with recessive traits is that dogs ...

Over the past two decades, usage of genetic testing technologies has revolutionized the world of dog breeding. Once limited to selective breeding practices based upon the characteristics or disease states that could be physically observed in a dog, genetic testing has allowed dog breeders to uncover the inherited genetic variants (mutations) that are not being expressed in an individual but may be expressed in their offspring. By comparing the disease-associated mutations inherited by a dog to those of a prospective mate, informed breeding decisions can be made to avoid producing puppies with these diseases. However, despite the immense value of genetic disease testing in the production of healthy puppies, incorrect assumptions about the parentage of a litter can have disastrous consequences for the health of a kennel, even when parental genetic disease testing results are 100% accurate.

Clear by Parentage/Hereditary Clear

In ideal situations, potential dams and sires are tested for breed-specific, disease-associated genetic mutations prior to being bred. If both parents are found to be free of these mutations (often referred to as being “clear”), it can be assumed for practical purposes that the offspring are also clear of the same mutations. With this understanding, it is common ...

Every veterinarian leaves veterinary school with a mental laundry list of animal diseases and their textbook presentations. While this knowledge serves the young graduate well in most circumstances, with clinical experience and mentorship comes the ability for veterinarians to expand their mental notes about the various ways some diseases can present in the real world. For some inherited canine diseases, genetic testing has allowed the practitioner to correlate a broader set of clinical signs for dogs affected by identical underlying genetic mutations. This variability in disease phenotype, known as variable expressivity, is a result of the combined effect of all genetic and environmental factors influencing each individual and can add significant challenge to some diagnoses. However, supplementing a disease workup with genetic test results can prove invaluable in diagnosing inherited diseases that have the frustrating attribute of rarely presenting the same way twice.

Collie Eye Anomaly

Now known to occur in well over a dozen breeds, the recessively inherited collie eye anomaly or CEA (also known as choroidal hypoplasia) is a relatively common eye disease of dogs and a good example of a disorder which can have diagnostic challenges due to its phenotypic variability. CEA is caused by a deletion ...

The discovery of various disease-associated genetic mutations has greatly changed the way some inherited canine diseases are categorized and perceived by the veterinary community. Through the use of genetic testing developed to identify these discovered mutations, various diseases which were once assumed to have a single underlying molecular cause (due to similarity between disease states) have been found in some cases to actually be caused by many different mutations, often in different genes. This phenomenon, known as genetic heterogeneity, elucidates the way genes work together in pathways and how a disruption in different genes of a pathway may result in similar or nearly identical disease states despite seemingly disparate underlying molecular etiologies. Understanding that there may be one of many different genetic mutations responsible for a dog’s clinical signs can help plot a better course for veterinarians to obtain an accurate, definitive diagnosis and in some cases, may alter treatment strategies.

Pet Owner vs Breeder

The accuracy and specificity of an inherited disease diagnosis are particularly important in the world of dog breeding where every potential health issue must be considered prior to breeding. Unlike general pet owners who may not need to know the specific underlying molecular mechanisms of ...

While advancements in science, medicine, and agriculture have played a role in decreasing the relative importance of the dog in human survival, their importance as pets, companions, and surrogate family members may be greater than ever. Once more commonly selected for their athletic prowess and behavioral traits, the rise of dog fancying over the past 250 years has elevated the importance of canine aesthetics to previously unprecedented heights. As a result, dog breeders have historically gone to great lengths to produce dogs with unique phenotypic characteristics desirable to potential pet buyers. While most of these characteristics are simple, mendelian genetic traits without health concerns, some desirable and interesting traits such as the merle coat color pattern are unique to domestic animals and bring with them a complexity and potential health concerns that veterinarians should be aware of in their goal of facilitating canine health and wellbeing. 

An Interesting Mutation for an Interesting Haircoat

In 2006, Dr. Leigh Anne Clark and others identified a semi-dominant genetic mutation responsible for the merle coat color pattern commonly seen in numerous dog breeds including the Australian shepherd, collie, border collie, and dachshund. Merle coat color is marked by areas of normal, eumelanistic pigmentation ...

Genetics play an enormous role in the health of dogs walking through the doors of any veterinary hospital. However, the treatment of an animal with an inherited disease rather than proactive testing of the genetic mutations responsible for disease has been the traditional role of the veterinarian. With an increase in the availability of canine genetic disease testing and great improvements in the ease and convenience of ordering genetic testing through Paw Print Genetics, more and more dog breeders and their clients are having genetic testing performed preemptively and learning the benefits of these powerful technologies. As a veterinarian, understanding the basics of genetic testing and how genetic test results can be used to prevent and diagnose disease will keep you current and prepared for your clients as these technologies inevitably become a more significant part of clinical veterinary practice.

One of the more challenging but important aspects of canine genetic testing is deciding what recommendations to make when a dog or one of its relatives are found to be at risk for (or affected with) an inherited disease. Appropriate testing recommendations for the relatives of affected dogs may be crucial for prevention of additional affected puppies and identification of ...

Discovery of disease-associated, canine genetic mutations has greatly increased over the past two decades. As a result, identification of these mutations through genetic testing has quickly become a useful tool for dog kennels and veterinary practices by allowing for the identification of asymptomatic disease carriers, diagnosis of affected dogs, and prevention of inherited diseases through informed breeding practices. However, because mutation discovery is often funded by specific breed clubs with interest in a breed-related disease concern, study investigators may not perform extensive, species-wide population studies for a newly discovered mutation. Therefore, in many cases, additional breeds inheriting the same mutation (and developing the same disease) may remain unknown for quite some time after the initial discovery.

As any modern veterinarian can attest, for better or worse, animal lovers have more veterinary medical information at their fingertips than ever before. Occasionally, at Paw Print Genetics, we are contacted by breeders or owners whose veterinarian had opted not to pursue a diagnosis that the client suspected because of the veterinarian’s historical understanding of a disease’s breed-specific distribution rather than the current knowledge. For veterinarians building a differential diagnosis list, keeping the mind open to a particular inherited disease manifesting in an unexpected ...

The breeding of dogs identified as genetic carriers of recessive disease is a hotly debated topic in the canine breeding world with many breeders firmly entrenched in their own personal approach to the issue. With increasing regularity, dog breeders and their clients are bringing genetic questions (including those about breeding carriers) to their veterinarians under the assumption that most veterinarians would be up to speed on the current information and genetic testing available. Unfortunately, at Paw Print Genetics we occasionally speak to breeders whose veterinarians have given them advice about breeding carriers that may not be in the best interest of the kennel or the breed. Given the large number of variables and differences between the way kennels are operated and the recessive disease risks of individual breeds, there is not necessarily a breeding approach that would be appropriate in 100% of cases. However, understanding some guiding principles and the potential ramifications of doing so, can help a veterinarian advise their dog breeding clients in a way that will help them meet their goals without increasing the incidence of recessive diseases in a kennel or in the breed.

What is a “Carrier” of a Recessive disease?

As a quick refresher ...

Some of the most emotionally challenging canine cases seen in the veterinary hospital are those involving serious illnesses of newborns or young puppies. Owners’ joyous expectations of a long, healthy relationship with their new puppy makes a disease which decreases that puppy’s quality of life or results in early euthanasia, all the more heartbreaking. Though infectious diseases like parvovirus are often of particular concern in young pups, some puppies ending up on the exam room table show signs of one of a wide array of inherited diseases caused by a known genetic mutation. Unfortunately, limitations in available therapies for many inherited diseases often lead to frustrating and emotional outcomes for all the parties involved; veterinarians and veterinary staff included. Thereby, making prevention of inherited disease through the use genetic testing, an essential part of healthy dog breeding.

Historically, methods to prevent inherited diseases have been limited to selective breeding practices. However, an inability to identify asymptomatic carriers of recessively inherited diseases or dogs in the preclinical phase of late-onset inherited diseases, have traditionally made great reductions in disease incidence difficult to obtain through selective breeding alone. Genetic testing is now playing an important role in identifying these dogs such that ...

Veterinarians examine, treat, and diagnose dogs with inherited diseases daily. Though treatments to fix some inherited disorders such as cryptorchidism and umbilical hernias are relatively safe and effective, rarely are the inherited disorders seen in practice remedied with a simple, relatively low-cost solution. In fact, in many cases of inherited disease, treatment options are extremely limited or non-existent. Therefore, an option to prevent these diseases before they occur would be preferable in most circumstances. Genetic disease testing made possible by the discovery of the causal mutations has become the best medicine to combat many inherited conditions.

Genetic testing of dams and sires has become commonplace in many dog breeds as breeders have recognized the power of identifying those dogs at risk of producing puppies with inherited diseases. Unfortunately, however, some breeders have been slow to adopt the routine use of genetic testing as they continue to rely on traditional selective breeding techniques. Limited by the inability to identify unaffected carriers of disease, selective breeding has historically proven relatively ineffective in the pursuit of large reductions in disease incidence.

Adult and late-onset inherited diseases pose an extra challenge in selective breeding because dogs become sexually mature before signs of the disease ...