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Jack Russell Terrier

origin: Australia · 11 figures in the corpus · Q38287

Every figure below carries this breed's name or id in its source study -- grouped by what it measures, not ranked. A breed appearing under a study here does not mean every other breed was tested and came back negative; it means this is what has a named source so far. See each figure's own page for its caveats.

Longevity

13.3 years (median survival) verified

Jack Russell Terrier: median survival age, UK veterinary clinic population

  • UK primary-care veterinary clinic population (VetCompass), not a census of all dogs of the breed.
  • Hazard ratio vs. the crossbred reference group: 0.79 (95% CI 0.77-0.8, p<0.001).
12.72 years (life expectancy at birth) verified

Jack Russell Terrier: life expectancy at birth, UK veterinary clinic population

  • UK primary-care veterinary clinic population (VetCompass), not a census of all dogs of the breed.
  • Life expectancy at birth (cohort life-table method), a different statistic from a Kaplan-Meier median survival age -- do not compare directly against McMillan 2024's figures.

Size & head shape

1 size class (1=Small, 2=Medium, 3=Large) verified

Jack Russell Terrier: body size class -- Small

  • Body size and cephalic index classification per Supplementary Table S5; for breeds absent from the study's primary source lists, assigned by majority agreement among Dogs Trust canine-behaviour experts rather than measured directly on dogs.
2 cephalic type (1=Brachycephalic, 2=Mesocephalic, 3=Dolichocephalic) verified

Jack Russell Terrier: head-shape (cephalic index) classification -- Mesocephalic

  • Body size and cephalic index classification per Supplementary Table S5; for breeds absent from the study's primary source lists, assigned by majority agreement among Dogs Trust canine-behaviour experts rather than measured directly on dogs.

Group

1 group membership (see subject) verified

Jack Russell Terrier: UK Kennel Club group: Terrier; FCI group: Terriers

  • KC/FCI group columns record nomenclature presence only, per the table's own caption -- the study did not use group as an analysis variable.

Temperament

30.3 percent scored 'high' fear preliminary

Jack Russell Terrier: share of surveyed dogs scored high on the Fear trait (Salonen 2020, Finnish pet dogs)

  • Self-selected online convenience sample of Finnish pet owners, not a random sample of the breed or of all dogs.
  • Restricted to breeds with at least 50 surveyed dogs to avoid small-sample noise.
57.7 percent scored 'high' noise sensitivity preliminary

Jack Russell Terrier: share of surveyed dogs scored high on the Noise sensitivity trait (Salonen 2020, Finnish pet dogs)

  • Self-selected online convenience sample of Finnish pet owners, not a random sample of the breed or of all dogs.
  • Restricted to breeds with at least 50 surveyed dogs to avoid small-sample noise.

Bite rate

14.749 bites per 1,000 licensed dogs preliminary

Jack Russell Terrier: NYC bite reports per 1,000 licensed dogs of this breed, all years combined

  • One city only (NYC); breed labels are self-reported, not verified against a registry or genetic test.
  • Licensed-dog counts are active-license snapshots per extract year, not a true owned-dog population.

Other

1 purpose class: hunting: terrier verified

Jack Russell Terrier: purpose class 'hunting: terrier', from FCI group: Terriers

  • Registry group membership at time of the source table, not an independent behavioural assessment.
503 puppies registered verified

Jack Russell Terrier (Terrier group): UK Kennel Club new registrations, 2025; +235.3% vs 2016

  • UK-only; a breed with 0 or blank registrations in a year may be newly recognised, temporarily unregistered, or genuinely absent that year -- the source table does not distinguish these.
4.0 average litter size (puppies) verified

Jack Russell terrier: average litter size, Danish Kennel Club registrations Aug 2022-Jul 2023