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Sealyham Terrier

The breeds · terrier

AKC Terrier · UKC Terrier · FCI standard 74

Sealyham Terrier.

UKC: developed in the mid 19th century by Captain John Edwardes in the Haverfordwest region of South Wales as the ideal working terrier to dig out badgers and fox and to accompany his Otterhounds. A strong, active working terrier with as much substance as possible for a dog quick and capable of digging and battling its quarry underground. FCI 74: Group 3 Section 2 (small-sized terriers), without working trial; sturdy, game, workmanlike. RKC: bred to work alongside Otterhounds and go to earth after otter; RKC lists it as a vulnerable native breed (UK)..

Breed sets the odds. The parents set the dog. Every number here shows its source, its spread and how sure we are. Nothing on this page is a prediction about one dog.

13.1YRMedian lifespan12.3 to 16, measured on real dogs.
11INHeightall 10.5. An ideal from the standard, not a range.
18–24LBWeight, all linesbreed dogs 19.8 to 24 lb; breed bitches 18 to 18.1 lb.
1HRSExercise, every dayRKC: exercise up to 1 hour per day; size small; home: small house. AKC page: energy level 3 of 5, mental stimulation needs 4 of 5.. The constraint most homes get wrong.

The body

What the breed is built like. Registry standards give an ideal, not a range.

Height at the shoulder

10.5 in

Breed clubAKC breed standard, 1974

AKC prints an ideal; UKC and FCI print a ceiling. No floor is printed, so low is left blank.

Weight

bitches 18 to 18.1 lb

Breed clubUnited Kennel Club

AKC prints no female number; range spans UKC and FCI.

dogs 19.8 to 24 lb

Breed clubAKC breed standard, 1974

The AKC figure runs heavier than the UKC and FCI ideals; both stand.

Coat

AKC: weather-resisting; soft dense undercoat and hard wiry topcoat; silky or curly coat a bad fault. Color all white, or with lemon, tan or badger markings on head and ears. UKC and FCI 74 agree (FCI allows brown, blue and badger pied head and ear markings). RKC: does not shed. Wikipedia: long coats dirty easily in muddy weather.

Breed clubAKC breed standard, 1974

AKC, UKC and FCI agree on structure; the allowed marking colors differ slightly.

Shedding

Shedding 3 of 5 (AKC breed page trait score)

Breed clubAKC

AKC breed page trait score, 1 to 5: a breed-club tendency, never a measurement.

Heat tolerance

3 of 5 · AKC: weather-resisting coat of soft dense undercoat and hard wiry topcoat. UKC: weather-resistant double coat. FCI 74: long hard wiry topcoat with weather-resistant undercoat.

DerivedAKC breed standard, 1974

Derived from the standard's coat (medium double = 3). No measured data.

How long they live, and what they cost

Measured on real dogs, with the sample and the spread. Never a guess.

Median lifespan

13.1 years (12.3 to 16)

MeasuredMcMillan KM, 2024

UK dogs, Dogs Trust table, accessed Oct 8 2026. Small sample, wide interval.

The dog at home

What the breed asks of a day. The first thing most homes get wrong.

Exercise need

RKC: exercise up to 1 hour per day; size small; home: small house. AKC page: energy level 3 of 5, mental stimulation needs 4 of 5.

Breed clubThe Royal Kennel Club

RKC band 'up to 1 hour' mapped to 60 minutes. AKC bands shown as text, not mapped.

Energy

3 of 5

Breed clubAKC

AKC breed page trait score, 1 to 5: a breed-club tendency, never a measurement.

Grooming load

4 of 5 · RKC: grooming every day; coat length long; does not shed. RKC history: the breed has dwindled, 'perhaps because of the requirement for the maintenance and trimming of the coat'. AKC page: coat grooming frequency 3 of 5, shedding 3 of 5.

Breed clubThe Royal Kennel Club

RKC 'every day' mapped to 4 (daily or regular clipping). AKC bands not mapped.

The work

What it was built to do in the field, and what a test or trial asks of it.

Role

UKC: developed in the mid 19th century by Captain John Edwardes in the Haverfordwest region of South Wales as the ideal working terrier to dig out badgers and fox and to accompany his Otterhounds. A strong, active working terrier with as much substance as possible for a dog quick and capable of digging and battling its quarry underground. FCI 74: Group 3 Section 2 (small-sized terriers), without working trial; sturdy, game, workmanlike. RKC: bred to work alongside Otterhounds and go to earth after otter; RKC lists it as a vulnerable native breed (UK).

Breed clubUnited Kennel Club

UKC, FCI and RKC wording. RKC is the UK parent registry; the breed is a vulnerable native breed there.

Primary game

RKC: otter (going to earth), and also badger, fox and polecat. UKC: badger and fox. Wikipedia: pest control, small game and vermin, particularly badgers; Sir Jocelyn Lucas used them for badgers (usually relocated), otters, stoats and squirrels in the 1920s and 1930s.

Breed clubThe Royal Kennel Club

RKC and UKC state the quarry; Wikipedia adds the Lucas account.

Also used on

Wikipedia: ratting and mousing; some owners report they will retrieve if trained.

EditorialWikipedia

Single editorial source.

Search pattern

RKC: Captain Edwardes selected ruthlessly; dogs that showed reluctance to stand their ground or to kill were shot. UKC: fearless, with a friendly nature; capable of digging and battling its quarry underground. Worked with Otterhounds (a pack of hounds), the terrier going to earth after the hounds marked the quarry.

Breed clubThe Royal Kennel Club

The Otterhound partnership is stated by RKC and UKC; no source prints a voice statement.

Field trial standard

FCI 74: Group 3 Terriers, Section 2, 'without working trial'. No earthdog or field-test rules read.

Breed clubFCI-Standard N° 74, 2026

FCI classification only.

Water work

RKC: the parent club's centenary show included a demonstration of Sealyhams working in the river Seal with Otterhounds. No registry standard states a water requirement.

Breed clubThe Royal Kennel Club

One RKC sentence describing a demonstration; the original otter work is stated as the breed's purpose.

Cold water

4 of 5 · RKC: river work with Otterhounds; weather-resisting double coat per AKC, UKC and FCI.

DerivedThe Royal Kennel Club

Derived from the weather-resisting double coat and the stated river work; a small, low terrier. No measured data.

How common the problems are

Evaluated dogs skew toward breeding stock; the numbers are still the best there are.

Most common disorders

Wikipedia: primary lens luxation (autosomal recessive ADAMTS17 mutation; painful glaucoma and blindness); the breed is predisposed to atopic dermatitis; low numbers, with popular-sire effect and genetic diversity named as problems. AKC parent-club list: ACVO eye exam and PLL DNA test.

EditorialWikipedia

Wikipedia summary of cited work; the primary papers were not read.

More

akc bands

AKC breed page trait scores (1-5): Energy Level 3; Mental Stimulation Needs 4; Trainability Level 4; Barking Level 4; Watchdog/Protective Nature 5; Good With Young Children 3; Openness To Strangers 4; Good With Other Dogs 3; Shedding Level 3; Coat Grooming Frequency 3; Drooling Level 1; Affectionate With Family 5; Playfulness Level 3; Adaptability Level 4.

Breed clubAKC

Fourteen AKC bands in one row; the selector reads each by name. Breed-club ratings: a tendency, never a measurement.

What to ask a breeder for

The health clearances the breed’s own club and registry name. Reference only: what to ask for, never a statement about any dog’s health.

How to read this page

Every value carries a label. Measured means peer-reviewed data on many dogs. Studied means peer-reviewed, smaller or indirect. Breed club means a club or registry states it. Editorial means expert opinion with no measurement behind it. Where two good sources disagree, both are shown and neither is averaged.

Published when the entry rests on the best information available from no fewer than three independent sources, checked by a second pass that did not write it. 8 sources on this page. Found something wrong? Tell us and the correction is logged with its date.

Also called
Sealyham, Sealy, Welsh Border Terrier, Cowley Terrier

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