Mastiff

Pinschers & molossoids

Giant

Median 9 y

FCI group 2 · Pinscher and Schnauzer, Molossoid and Swiss Mountain Dogs · Derived from the adult weight midpoint (77.1 kg)

Median survival across 3,259 UK dogs (VetCompass, McMillan 2024) · half live 6–11 y

A mastiff is a large and powerful type of dog. Mastiffs are among the largest dogs, and typically have a short coat, a long low-set tail and large feet; the skull is large and bulky, the muzzle broad and short (brachycephalic) and the ears drooping and pendant-shaped. European and Asian records dating back 3,000 years show dogs of the mastiff type.

Courageous

Dignified

Good-natured

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

Adult weight

Reference

Male

72.6–104.3 kg

Female

54.4–77.1 kg

100

150

Breed club figure (the American Kennel Club)

Weight for age

Stock data

Male

Female

Expected range

Expected range from the breed's own adult weight, kilograms. Growth reference: Hawthorne et al. 2004, WALTHAM, n=4 English Mastiffs.

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 72.6–104.3 kg and females 54.4–77.1 kg. Most are close to their full size by around 16 months, though the last little bit of filling out takes longer. Growth reference: Hawthorne et al. 2004, WALTHAM, n=4 English Mastiffs.

No Mastiff 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 9 y. Median survival across 3,259 UK dogs (VetCompass, McMillan 2024) · half live 6–11 y. How the later years go comes down to weight, teeth, exercise and regular check-ups far more than to the breed.