The Sealyham Terrier Is A Small Dog From Wales, United Kingdom.

Sealyham Terrier Dog

The Sealyham Terrier is a unique and rare dog breed that originated in Wales, U.K.. It gets its name from the home of the original breeder (John Edwardes), who lived at Sealyham House in the Welsh county of Pembrokeshire.

Edwardes wanted to develop a strong terrier breed for keeping vermin down and for hunting small animals. One of the main aims was to develop a white dog, easily seen and distinguishable from the prey animals.

A white Sealyham terrier standing on grass
A Sealyham looking alert!

Sealyham Terrier Temperament

Like most dogs, the Sealyham likes to be with it’s owner, and forms strong bonds of affection and loyalty. However, unlike some other dog breeds, they are also happy to be left alone for periods of time, and will not usually become bored nor destructive.

Originally bred to control vermin such as rats, and for hunting small animals, this dog is most comfortable in the countryside, but also does well in urban settings. They can be energetic and boisterous, bouncing around with excitement, but are mostly well-behaved.

They make good family pets, and enjoy playing with older children and other dogs. If introduced at a young age, they can also get along well with smaller family pets such as cats and rabbits.

This breeder can be quite loud, barking at almost anything that moves, so may not be best suited to apartment life.

Breed History

The man most responsible for developing the breed was John Edwardes, from Pembrokeshire in Wales, U.K.. He wanted a small white dog with a wiry coat for hunting vermin. He used the Fox Terrier, the Welsh Corgi and the English White Terrier (now extinct) in the breeding program.

The white color was important to Edwardes, because it meant the dog would be clearly visible to the hunter, and easily distinguishable from the prey (which be as large as a badger).

The breeding program started around 1850, but Edwardes did not keep any records. However, we do know that he was strict about culling puppies that were weak nor did not have the properties he was striving for. He only used the very best dogs for further breeding.

Edwardes died in 1891, but other dog breeders took over and continued the effort. The Sealyham Terrier was recognized as a breed by both the AKC and the U.K. Kennel Club in 1911.

In the 1920s and 1930s the breed was used to hunt larger animals such as stoats, weasels, squirrels and badgers. But they retained an inherent instinct to go after the smaller animals like rats and mice.

A Sealyham terrier sitting on a marble wall outside in the sun
Enjoying the sun

After the First World War, the Sealyham Terrier became much more popular in both the U.K. and in the U.S.A..  In particular, Hollywood stars were taken by the appearance and temperament of the breed. Famous owners included Bette Davis, Humphrey Bogart, Elizabeth Taylor, Cary Grant, Alfred Hitchcock, and writer Agatha Christie. In the U.K., King George V and Princess Margaret both had Sealyham Terriers.

In recent years the popularity of the Sealyham has declined, and in 2008 the U.K. Kennel Club stated that only 43 new dogs had been registered. This makes it one of the most endangered native dog breeds. The Kennel Club has put the blame on the development of “designer hybrid breeds”. In addition, the breed has become less able to perform as a working dog after tail docking was banned.

Small working dogs can get stuck down holes, and need a short sturdy tail for the hunter to pull them out by. Undocked Terrier tails are too long and thin near the end for this trick to work, and so Sealyhams are not as useful as they used to be.

A Sealyham puppy sitting in a stone nook
Sealyham puppy

Vital Statistics;

Height; 10 to 11 inches

Weight;  20 lbs to 25 lbs

Lifespan;  12 to 15 years


The body should be white, but the head and face may have some black or tan markings, or a badger-like head coloring.

Ease of Training

The Sealyham Terrier is a happy, energetic dog, keen to please its owner, but they can have an independent streak which makes them challenging to train. They pick up new ideas quickly, but have a quirky nature.

We recommend taking your Sealyham puppy to puppy training classes as soon as your vet says its OK for the dog to mix with others. This introduces the dog to new sights, sounds and smells, and of course to strange people and other dogs.

Early introduction to training must be followed by regular and consistent training into adulthood.


Like all terrier breeds, the Sealyham is alert and vigilant, especially for any small movements or sounds that could be a rat or a mouse. This means they are aware of what’s going on in the vicinity, and they make good watchdogs. They will tell you if something unusual is going on by barking.

However, despite their vigilance and big heart, their sheer size means that they are not good guard dogs. They are just too small to be much of a deterrence to unwanted intruders. If you need a dog for a little extra protection, I suggest you look at a bigger breed.

A white Sealyham terrier standing in a grassy field
A Sealyham terrier outside in a field


The Sealyham Terrier has a double-layer weatherproof coat that needs to be brushed with a wire comb to prevent matting. Also, being small dogs, they are close to the ground and tend to pick up mud and dirt in wet weather.

If you are intending to show your dog, an easy solution is to have the coat trimmed short. This is a low maintenance option! Like all terrier dog breeds, the Sealyham does not shed much, so you won’t find loads of dog hair in your vacuum cleaner!

Health Considerations

This is a sturdy breed with few health issues, however there are 2 conditions that potential owners need to be aware of.

1. Degenerative myopathy

2. Lens luxation.

The first is a progressive incurable condition of the spinal cord. It is similar to Lou Gehrig’s Disease in humans.

The second is a condition where the lens in the eye moves from its correct position.  It’s now possible to get a DNA test to identify dogs that carry the genes for these conditions, and exclude them from breeding.

Famous Sealyham Terrier dogs

There are quite a few Sealyham Terriers with famous owners, as mentioned above, but I couldn’t find any dogs that are famous in their own right. Please let me know if you know of one, using the Contact me link. Thank you!

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