Jack Russell Terrier

Terriers

Small

Median 13.3 y

FCI group 3 · Terriers · Derived from the adult weight midpoint (5.5 kg)

Median survival across 32,663 UK dogs (VetCompass, McMillan 2024) · half live 10–15 y

The Jack Russell Terrier is a British breed of small terrier. It is principally white-bodied and may have a smooth, rough, or broken coat, with markings of various colours.

Energetic

Bold

Clever

Summary from Wikipedia (CC BY-SA) · reference ranges from the Kintail breed dataset

Adult weight

Reference

Male

5–6 kg

Female

5–6 kg

The breed standard (FCI 345)

Varieties

Reference

Smooth

Small build

5–6 kg

25–30 cm

FCI 345 admits three coats — smooth, broken and rough — under one size standard; same size as the parent, coat only; one range for both sexes

Broken

Small build

5–6 kg

25–30 cm

FCI 345 admits three coats — smooth, broken and rough — under one size standard; same size as the parent, coat only; one range for both sexes

Rough

Small build

5–6 kg

25–30 cm

FCI 345 admits three coats — smooth, broken and rough — under one size standard; same size as the parent, coat only; one range for both sexes

FCI 345 divides this breed by coat and face. The varieties are the same size — the coat is the only difference.

Weight for age

Stock data

Male

Female

Expected range

Expected range from the breed's own adult weight, kilograms. Growth reference: Salt et al. 2017, WALTHAM (under 6.5 kg band).

Heat cycles · females

Stock data

First heat

8–12 mo

typical

Interval

180 d

typical

Bleeding

~9 d

typical

Proestrus 9d

Estrus 9d

Diestrus 52d

Anestrus 110d

General figures for dogs, not for this breed — individual cycles vary widely.

Questions people ask

Adult males usually weigh 5–6 kg and females 5–6 kg. Most are close to their full size by around 19 months, though the last little bit of filling out takes longer. Growth reference: Salt et al. 2017, WALTHAM (under 6.5 kg band).

No Jack Russell Terrier cycle figures are published here yet, so this is general guidance rather than a breed number: most females have a first season somewhere between six and fifteen months, and cycles then settle to roughly every 180 days. Smaller breeds tend to start earlier and larger ones later.

The median is 13.3 y. Median survival across 32,663 UK dogs (VetCompass, McMillan 2024) · half live 10–15 y. How the later years go comes down to weight, teeth, exercise and regular check-ups far more than to the breed.