Genetics
Dog Coat Texture Genetics: What Makes a Coat Curly, Wavy, or Straight
Whether your dog has a tight curl, gentle wave, or a flat straight coat is determined by three specific genes. Here's the complete genetics of dog coat texture.
June 28, 2024 · 6 min read
The Three Key Coat Genes
- FGF5 (Fibroblast Growth Factor 5): Controls coat length. L allele = long coat; l allele = short coat. Homozygous ll = fluffy/long coat. Most Poodles and doodles are ll.
- KRT71 (Keratin 71): Controls curl. Cu allele = curly; cu allele = straight. Homozygous Cu/Cu = tight curly coat. Heterozygous Cu/cu = wavy. cu/cu = straight coat.
- RSPO2 (R-spondin 2): Controls furnishings (mustache, eyebrows, long leg hair). F allele = furnished (Poodle-style); f allele = non-furnished (smooth face). F/F or F/f = furnished coat appearance.
Why F1 Cavapoos and Doodles Vary in Coat Type
In an F1 cross between a furnished, curly Poodle and a non-furnished, straight-coated Cavalier, every puppy will be heterozygous at each locus — F/f at RSPO2 and Cu/cu at KRT71. This produces the typical F1 'wavy furnished' coat. But if the Cavalier parent carries any curl or furnishing alleles (possible in some lines), coat types can vary more within the litter.
Predicting Coat in F1B and F2 Generations
F1B doodles (75% Poodle) are more likely to be Cu/Cu at KRT71 (curly) and F/F at RSPO2 (fully furnished) because the Poodle parent's contribution is doubled. F2 doodles have the most coat variation — cu/cu (flat coat) puppies can appear alongside tight curls in the same litter. DNA coat testing of breeding dogs allows breeders to predict coat types and avoid producing the lowest-shedding coat puppies when coat type matters to buyers.
DNA Coat Testing
Many canine DNA panels now test for RSPO2, KRT71, and FGF5 as part of their trait panels. This allows breeders to predict with high accuracy what coat types their litter will produce — especially useful for F1B and multigenerational doodle programs where coat consistency is a priority for allergy-sensitive buyers.