In the dynamic world of canine genetics, phenotypic testing has become an increasingly popular tool among breeders and dog enthusiasts. When I first started offering canine genetic services, the demand for color tests was quite rare, often limited to the E (extension) Locus. Today, phenotypic testing has become a significant driver in the industry, encompassing a wide range of traits from coat colors to furnishings and hair length. What’s behind this surge in interest? What has changed?
Known for my fascination with the genetics that shape our beloved canine companions, I have become particularly intrigued by the rising trend in phenotypic testing. This trend encompasses everything from coat colors to furnishings and hair length. Today, we explore this growing interest through the eyes of Genetic George, accompanied by Charlie, the Boston Terrier, and Mary, the Brussels Griffon.
Phenotypic tests in dogs are used to identify and predict physical traits that can be observed, like coat color, hair length, and facial hair features known as furnishings. These tests help breeders and dog owners understand what a dog might look like as it grows, based on its genetics, but more importantly, in a breeding animal, what it may carry (is hidden), thus allowing you to manage the color and furnishings of offspring. For example, by using a phenotypic test, you can learn if a dog will have a specific coat color pattern, longer or shorter hair, or distinctive whiskers and eyebrows. This information is valuable for planning breeding programs, grooming needs, and ensuring the dog’s health and well-being.
Phenotypic testing refers to the examination of observable traits in dogs, which are influenced by their genetic makeup. While genetic testing has long been used to screen for hereditary health conditions, phenotypic testing focuses on physical characteristics, i.e., what a dog looks like. This trend is gaining momentum as breeders and dog enthusiasts seek to predict and select for specific traits, enhancing not only the appearance but also the health and functionality of dogs.
As Genetic George would say, “It’s not just about what we see; it’s about understanding the story written in their genes.” This sentiment captures the essence of phenotypic testing—bridging the gap between science and aesthetics to create a deeper understanding of our canine friends.
To illustrate the nuances of phenotypic traits, let’s consider Charlie and Mary, two distinct yet beloved dogs. Charlie, a lively Boston Terrier, sports a classic tuxedo coat pattern, a characteristic trait of his breed. However, his coat’s exact shades and markings piqued my curiosity, leading to an exploration of the genetic factors behind coat color variations.
Traditionally, Boston Terriers are known for their iconic black-and-white tuxedo appearance. However, some may carry genes for brown (B Locus) or diluted colors (D Locus), leading to variations like brown or lilac coats. These variations result from a complex interplay of multiple genetic loci, including A (agouti), B (brown), D (dilute), E (extension), G (graying), K (dominant black), M (merle), and S (spotting). Each Locus contributes to the diverse and vibrant array of colors and patterns we see in different breeds. The complexity doesn’t stop there; even within the Merle pattern there are variations like cryptic, atypical, and harlequin. For those interested in Merle patterns, an excellent reference can be found at: https://merle-sine-insertion-from-mc-mh.webnode.page/
Mary, on the other hand, is a Brussels Griffon with distinctive furnishings—a term that refers to the facial hair that gives certain breeds their iconic look referred to as a dominant variant (167bp in the 3’-UTR sequence) of the R-spondin-2 (RSPO2) gene which produces this desired texture and growth pattern of coat. Mary’s beard and eyebrows are not just endearing features; they are expressions of specific genetic markers. This discovery sparked a conversation about how furnishings and other traits, like hair length, can vary even within breeds, making each dog unique.
Coat color is often one of the first traits people notice in a dog, and it’s a primary focus of phenotypic testing. Genetic testing can reveal the likelihood of certain colors and patterns in a dog’s offspring, helping breeders make informed decisions. This knowledge is particularly valuable for breeds with strict color standards or for those interested in rare coloration.
“A dog’s coat is like a painter’s canvas, rich with possibilities and surprises.” Indeed, understanding the genetics behind coat colors can help to preserve Breed Standards and enhance the predictability of breeding outcomes. However, one must also be cautious against breeding solely for aesthetic traits, reminding us that health and temperament should always be paramount.
Furnishings are another fascinating phenotypic trait. These tufts of hair on a dog’s face are not just cute—they’re a genetically determined feature. For example, in breeds like the Schnauzer or the Griffon, furnishings are a hallmark trait. In Mary’s case, her whiskers and eyebrows add character and charm, distinguishing her from other dogs.
Phenotypic testing for furnishings can help breeders understand whether a dog will develop these features, which is crucial for breeds where furnishings are a desirable trait. This knowledge allows for better grooming planning and can influence breeding decisions to ensure that these characteristics are maintained or enhanced in future generations.
Hair length is another trait of significant interest. Whether a dog has a short, sleek coat like Charlie or a longer, more luxurious one, like some Griffons, is determined by specific genes. Phenotypic testing can predict hair length, aiding breeders in selecting for this trait to meet Breed Standards or owner preferences. The FGF5 (Fibroblast Growth Factor 5) gene is the primary gene associated with hair length in dogs. This gene plays a crucial role in regulating the hair growth cycle, particularly the transition from the growth phase (anagen) to the resting phase (telogen). Mutations in the FGF5 gene can lead to longer hair by delaying the transition, thus allowing the hair to grow longer before it stops.
George, ever the thoughtful geneticist, points out that hair length can also affect a dog’s grooming needs and overall care. Longer-haired dogs may require more maintenance, while short-haired breeds might be easier to manage. Understanding these genetic factors helps prospective owners make informed decisions about the type of dog that best suits their lifestyle.
Phenotypic testing offers numerous benefits, from helping breeders plan more effectively to aiding in the preservation of breed characteristics. However, Genetic George emphasizes that this tool should be used responsibly. Breeding solely for specific phenotypic traits, especially those related to appearance, can lead to unintended consequences, such as compromising a dog’s health or temperament.
I advocate for a balanced approach, where phenotypic traits are considered alongside other important factors like genetic health, behavior, and the overall well-being of the dog. This holistic view ensures that the focus remains on raising healthy, well-adjusted dogs that thrive in their roles, whether as family pets, working animals, or show dogs.
In conclusion, the trend towards phenotypic testing is a fascinating development in the world of dog breeding. It can offer a deeper understanding of the genetic blueprint that shapes your breed, allowing for more informed breeding decisions and a greater appreciation of the diversity within breeds. Through the stories of Charlie and Mary, we see how these traits manifest in individual dogs, each unique and special in their own right.
As I like to say, “Embrace the color of your breed and the varieties they come in! Just like us, dogs come in all shades and hues, each coat color telling a unique story of genetics and history. Celebrate the diversity and beauty that nature brings to every canine coat!”
In the end, the goal of phenotypic testing should be to celebrate the incredible variety of dogs and to ensure that every dog, like Charlie and Mary, lives a happy, healthy life no matter what they look like. 
Phenotypic testing in dogs has significant applications beyond breeding and aesthetics, particularly in forensic science—a field I am passionate about (my first job was as a forensic scientist). This testing can be crucial in forensic cases involving dogs, such as bite incidents or accidents, where canine evidence-like hair can link victims and suspects due to the close contact that dogs have with their owners. When traditional DNA profiling doesn’t yield a match, phenotypic testing provides valuable clues about a dog’s appearance, including coat color, pattern, structure, body size, ear shape, and tail length. These traits are recognizable and easy to describe, even for non-experts, making them useful for investigators and eyewitnesses. By analyzing specific genetic markers, forensic scientists can create composite sketches of dogs involved in crimes, aiding in the investigation and identification process. This innovative approach showcases the practical benefits of phenotypic testing in providing crucial intelligence in criminal cases.
Want to learn and read more? People always ask me where a good place is to start: Where can I read and understand the basics of coat color? The good news is there are several excellent reference sites:
Dog Coat Colour Genetics: http://www.doggenetics.co.uk/; Wiley Online Library: https://onlinelibrary.wiley.com/doi/10.1111/age.13154; and Sheila Schmutz’s Dog Color: https://www.sheilaschmutz.net/Canid/DogColor.html
