Part XVII — Canine genetics and DNA testing

17.1 Genome basics

  • Dogs have 78 chromosomes (compared to 46 in humans, 42 in wolves — identical number as wolves).
  • The canine genome (~2.4 Gb) was sequenced in 2005; reference genome CanFam3.1 remains the most widely used.
  • Breed formation via strong selection has left 'signature' regions of reduced genetic diversity; inbreeding coefficients vary widely between breeds.

17.2 Common DNA tests and what they show

  • Breed identification tests (Embark, Wisdom Panel) — reasonably accurate for common breeds; less so for landraces or unusual mixes; useful for adopted-dog owners.
  • Health screens — DM (degenerative myelopathy), MDR1 (drug sensitivity), PRA (multiple forms), vWD (von Willebrand's), DCM (specific mutations), hyperuricosuria (Dalmatian), episodic falling (Cavalier), and dozens more.
  • Inherited condition screens for breeders — parent-club-recommended panels before breeding.
  • MDR1 test — critical for herding breeds before certain medication classes.

When a single male is over-used as a stud, his genes propagate through the breed disproportionately. Genetic diversity collapses. Recessive-disease frequency rises rapidly.

  • Documented examples across many breeds (Cavalier syringomyelia; Doberman DCM; Golden Retriever cancer risk).
  • Prevention — parent clubs increasingly track effective population size; outcrossing programmes have been used in a few endangered breeds to restore diversity (Dalmatian × Pointer to remove hyperuricosuria).

17.4 Coat colour genetics (owner-relevant)

  • The E, K, A, and D loci together determine coat colour and pattern for most breeds.
  • Merle (M locus) — desirable pattern but two-merle-copy (MM) crosses produce puppies with severe blindness and deafness (double-merle welfare problem). Ethical breeders never cross two merle dogs.
  • Piebald / white spotting genes — linked to deafness (Dalmatian, Bull Terrier, Boxer).
  • Coat texture genes — RSPO2 (wire coat), FGF5 (long coat), KRT71 (curly coat).

17.5 The Dog Aging Project and other research

  • The Dog Aging Project (University of Washington) — 40,000+ enrolled dogs; longitudinal study; publishes citizen-science-actionable data.
  • Broad Institute Canine Genome Project — deep sequencing and open-data.
  • Companion Animal Genome Sequencing Project (Indian institutional interest growing).
Vet-reviewed, non-prescriptive. This chapter has been reviewed by the Feme Solutions consulting vet panel. No specific drugs, doses, routes, or durations are named. Speak to a licensed vet before acting on any clinical claim.
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