Every Dog Coat Gene Explained: Length, Curl, Furnishings and Shedding
School · November21
Every Dog Coat Gene Explained: Length, Curl, Furnishings and Shedding
Length, curl, furnishings and shedding, in plain language, and what each one means for your brush.
Length (FGF5), curl (KRT71) and furnishings, the beard and eyebrows (RSPO2), explain most of what a dog's coat looks like. A fourth gene, MC5R, is linked to shedding, together with RSPO2. Together they decide how much hair your dog sheds and how much of it stays in the coat, and that second part is what decides how much brushing you will do.
If you own a poodle or a doodle, you have probably heard “it's the genes”. This is the plain version: what each gene does, how they combine into the coats you know, and what that means for your brush. It is a simplified model, and we say where it stops being accurate.
Why genes explain a coat
A coat is made of keratin, the same protein in every dog. What differs is how long the hair grows, what shape the hair shaft takes, and whether the face grows a beard. A 2009 study in Science by Cadieu and colleagues looked at 108 breeds and found that combinations of just three genetic variants explained the coat type of 95% of the dogs sampled. That is why a handful of genes is enough to explain a Labrador, a Schnauzer and a Poodle.
FGF5: how long the hair grows
FGF5 regulates the growth phase of the hair cycle. A long growth phase means long hair. The long-coat variant is recessive, so a dog needs two copies of it (written L/L) to have a long coat. Dogs with a short growth phase have a short coat and shed in seasonal waves. Dogs with a long one keep growing the same hair for months or years.
KRT71: how curly the hair is
KRT71 affects the keratin in the hair shaft. A round follicle produces straight hair. An oval follicle produces a twisted, curled shaft. The genotypes are usually written n/n (straight), n/Cu (wavy) and Cu/Cu (curly).
Curl matters for brushing because a curled strand wraps around its neighbours. Loose hair that would fall out of a straight coat gets caught in a curly one. Our post on the curl gene goes deeper, and the line-brushing guide shows the technique that works on it.
RSPO2: beard, eyebrows and a coat that holds on
RSPO2 controls furnishings: the beard, moustache and eyebrows you see on a Schnauzer, an Airedale or a Poodle. A 167-base-pair insertion in this gene gives the furnished look, and it is dominant. A study by Hayward and colleagues (2016, Nature Communications) also linked RSPO2 to shedding: breeds that shed very little are typically homozygous for the furnishings variant.
This is the part owners rarely hear. A dog that sheds little is not a dog that loses little hair. The hair still dies, it just doesn't fall out. It stays in the coat.
MC5R: the shedding gene
The same 2016 study associated shedding with both MC5R and RSPO2. The paper does not rank them, so we don't either. What we can say is that at least two genes are linked to how much a dog sheds, and that they are inherited separately from curl and length.
How the genes combine
Put length, curl and furnishings together and you get the familiar coats. This is the simplified teaching version.
| Genes present | Coat | Typical example |
|---|---|---|
| None of the three | Short, smooth | Labrador |
| Furnishings only | Short to medium, wiry, with a beard | Schnauzer |
| Furnishings + curl | Dense, wiry curl with a beard | Airedale Terrier |
| Length + curl | Long, curly, no beard | Irish Water Spaniel |
| Length + curl + furnishings | Long, curly, furnished | Poodle, and the classic doodle coat |
Bean, our toy poodle, has this last kind of coat. We haven't DNA tested him, so we describe his coat, not his genotype.
Improper coat: when two furnished parents have a smooth-faced puppy
The furnishings gene is really a three-version hierarchy: furnished (F), weak furnishings (Fw) and improper coat (ic). A furnished dog can carry a hidden improper-coat copy. If both parents pass it on, the puppy has a smooth face and a different coat from its parents. That is why two doodles can have a litter with very different coats.
What it means for your brush
Low-shedding is not low-maintenance. A furnished, curly coat keeps its loose hair, and the curl holds it in place. That is how a coat that “doesn't shed” turns into a coat that mats if it is not brushed through to the skin. It also explains why gear matters: any place where a strap, collar or harness rubs a curly, furnished coat is a place where loose hair has one more reason to felt together.
- Curly and furnished? Plan on brushing through to the skin every day or every other day, with a slicker brush and a metal comb to check.
- Wavy? Less often, but the armpits, ears and collar line still need a quick look.
- Straight and unfurnished? Less tangling, more shedding. A weekly brush is usually enough.
What this model leaves out
This is a simplified one-gene-per-trait model. Real coats also depend on density, undercoat and other variants. KRT71 is strongly tied to curl, but it is not the only variant involved, and not every curly coat is explained by it. Treat the table as a guide to why coats differ, not as a prediction for your dog. A coat-type quiz like ours asks about the coat you can see. It does not test DNA. Only a lab test does that.
Quick answers
Which gene makes a dog curly?
KRT71 is the main one. Dogs with two copies of the curl variant (Cu/Cu) have the tightest curl.
Which gene makes a dog low-shedding?
At least two genes are linked to shedding: RSPO2 (furnishings) and MC5R. Breeds that shed least typically carry the furnishings variant.
Why does a low-shedding dog still mat?
Because the hair that doesn't fall out stays in the coat. In a curly coat the curl holds it in place, so it tangles with its neighbours.
Can my quiz result tell me my dog's genes?
No. The quiz asks about your dog's coat. It gives you a coat profile and a brushing routine to start from. Only a DNA test shows genes.
Do all poodles and doodles have the same genes?
No. Doodle litters in particular can vary, which is why two siblings can have different coats.
Not sure which coat you have?
Take our free two-minute coat profile quiz. It asks about your dog's coat, not their DNA, and gives you a coat profile and a good starting point for a brushing routine. When you are ready, you can see our harness collection.