Understanding the Genetics of Dog Shedding

Dogs have earned their reputation as “man’s best friend” for their loyalty, companionship, and unwavering love. However, every dog owner can attest that shedding can sometimes be a challenging aspect of pet ownership. What many people may not realize is that the amount a dog sheds is not just a random occurrence; it is influenced by specific genes in their DNA. Recent research has uncovered two key genes that impact a dog’s shedding patterns: the MC5R gene and the RSPO2 gene. Let’s take a closer look at how these genes shape your furry friend’s shedding habits.

The MC5R-Gene & Dog Shedding

The MC5R-gene has been identified as a key player in determining the degree of shedding in certain dog breeds¹. This gene is expressed in the hair follicles of dogs and impacts their coat’s shedding level. A variant in the MC5R gene has been found to be associated with hair shedding².

Shedding due to the MC5R gene is inherited in an autosomal incomplete dominant fashion – this means that only one copy of the MC5R variant is required to produce the shedding effect³. So, if a dog inherits this variant from either of its parents, it can potentially shed more than dogs without this genetic variant.

The level of shedding is closely related to the “furnishings” gene, and having one copy of the shedding variant typically results in a low to moderate level of shedding⁴.

The RSPO2 Gene & Dog Shedding

Another gene associated with dog shedding is the RSPO2 gene⁵. Dogs with wiry coats are often low-shedding, and this trait is linked to a variant in the RSPO2 gene.

While the exact mechanism of how the RSPO2 gene affects shedding is still being studied, it’s clear that this gene plays a significant role in regulating a dog’s coat type. This discovery could explain why some breeds, like terriers, have wiry hair and shed less than other breeds.

Dog shedding can be influenced by multiple genes, including those at the Shedding (SD) locus, Furnishing (F) locus, and Improper Coat (IC) locus. By understanding these genetic influences, we can predict a dog’s potential shedding pattern and coat type. Let’s explore the different combinations of these genotypes and their impact on a dog’s shedding.

Genotypes, Loci, and Dog Breeds

Shedding (SD) Locus

The MC5R gene, located on the SD locus, is primarily responsible for controlling the degree of shedding in dogs. There are two variations of this genes¹. The two variations of this gene are SD (associated with heavy shedding) and sd (linked to light shedding).

• SD/SD and SD/sd: Dogs with these combinations are typically heavy shedders. This includes breeds like German Shepherds and Labs.
• sd/sd: Dogs with this combination are usually light shedders. Breeds like Bichon Frise and Maltese fall into this category.

Furnishing (F) Locus

The RSPO2 gene, located on the F locus, controls the presence or absence of furnishings, which include distinctive eyebrows, a beard, and a mustache seen in certain breeds². The variants are F (for furnishings) and f (lack of furnishings).

• F/F or F/f: Dogs with these combinations will have furnishings. Breeds like Schnauzers and Scottish Terriers demonstrate this trait.
• f/f: Dogs with this combination lack furnishings. Examples include Dalmatians and Bulldogs.

Improper Coat (IC) Locus

The FGF5 gene on the IC locus is responsible for coat length and texture³. A variant in this gene leads to an “improper coat,” which is a short, smooth coat seen in breeds that typically have a long, wavy, or curly coat. The variants are IC (improper coat) and ic (proper coat).

• IC/IC and IC/ic: Dogs with these combinations will have an improper coat. Breeds like the Australian Shepherd can exhibit this trait.
• ic/ic: Dogs with this combination will have a proper coat consistent with their breed standard.

The Interplay of Genes

The interplay between the SD, F, and IC loci can result in a wide variety of coat types and shedding patterns. For example:

• A dog with SD/SD, F/F, and ic/ic is likely to be a heavy shedder with furnishings and a proper breed-standard coat.
• A dog with sd/sd, f/f, and IC/IC would be a light shedder without furnishings and with an improper coat.
• A dog with SD/sd, F/f, and IC/ic could be a moderate shedder with some furnishings and a mix of proper and improper coat.

“Shedding scale and corresponding genotype combinations. Adapted from Hayward et al., 2016, where shedding rates were scaled as 0 (in minimal shedding breeds) to 1 (in heavy shedding breeds). Seasonal shedding breeds were not included in the original publication.” Source: vgl.ucdavis.edu.

It’s worth mentioning that mixed breed dogs can inherit genes that result in less or more shedding. Therefore, if you’re seeking a low-shedding dog, understanding the genetic makeup of the breed can be highly beneficial⁷. Let’s explore the genetics of popular dog breeds like Poodles, Labradoodles, and Bernedoodles to understand how they differ in shedding.

Poodles

Poodles are known for being low-shedding dogs⁸. They possess two copies of the furnishings gene and curl gene, and no copies of the shedding gene⁹. This genetic combination results in their hypoallergenic coats that shed minimally. The genotype is typically represented as FF for the Furnishing locus and sd/sd for the Shedding locus¹⁰.

Labradoodles

Labradoodles, a cross between a Labrador Retriever and a Poodle, are known for their allergy-friendly and low-to-non-shedding coats¹¹. However, their degree of shedding can vary depending on the specific Labrador and Poodle genes they inherit.

• F1 Labradoodles are 50% Poodle and 50% Labrador. While they can be low-shedding, they can also inherit the Labrador’s heavy-shedding trait.
• F1b Labradoodles, resulting from breeding an F1 Labradoodle back with a Poodle, are 75% Poodle and 25% Labrador¹². These dogs may or may not shed, but they have a higher chance of being low-shedders due to the higher percentage of Poodle genes.

Bernedoodles

Bernedoodles are a mix between a Bernese Mountain Dog, a heavy shedder, and a Poodle, a low shedder¹³. Like Labradoodles, the degree of shedding in Bernedoodles can vary depending on their specific genetic makeup.

• F1 Bernedoodles are 50% Poodle and 50% Bernese Mountain Dog. They can range from being low-shedding to moderate shedders.
• F1b Bernedoodles, resulting from breeding an F1 Bernedoodle back with a Poodle, are 75% Poodle and 25% Bernese Mountain Dog¹³. These dogs have a considerably higher chance of being low-shedding compared to their F1 counterparts due to the higher percentage of Poodle genes.

In conclusion, the degree of shedding in dogs can be attributed to their genetic makeup, with the MC5R and RSPO2 genes playing key roles. Understanding these genes allows potential pet owners to predict a dog’s shedding level, making it easier to find the perfect furry companion that suits their lifestyle and preferences. So, whether you prefer a low-shedding Poodle, a Labradoodle, or a Bernedoodle, genetic insights can guide you toward the ideal canine companion.

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Footnotes