Sealyham Terrier

Stuart Fitzgerald
Dr Stuart Fitzgerald (MVB MANZCVS, University College Dublin)
Photo of adult Sealyham Terrier

The Sealyham Terrier was originally bred as a hunting dog to pursue particularly tough prey, such as foxes, badgers and polecats. Hailing from Pembrokeshire, it was developed through a ruthless selection process, in which only the fiercest hunters were allowed to survive. Despite its street-fighting credentials, it is often said to have the sweetest nature of any of the terrier breeds, and makes a wonderful companion that is adaptable to many different living situations.

Though less boisterous and easily riled than some of the other terriers, they make good watch dogs, being alert and quick to bark. They are happy in the company of other animals, including smaller pets, and although they prefer to spend time with their owners, can amuse themselves when required. This is a very healthy breed, though eye disorders are an issue, and breeders should always be asked to provide certificates verifying their dogs’ health before one considers making a purchase. The Sealyham Terrier has an average life expectancy of 12–14 years.

About & History

The Sealyham owes its existence to the efforts of one man. Described by his contemporaries as an “eccentric sportsman”, Captain John Tucker-Edwardes was a Pembrokeshire squire of the nineteenth century. Having taken up hunting with hounds while stationed in Gibraltar with the Royal Welsh Fusiliers, he became a fanatical collector of hunting dogs on his return home to Sealyham House, overlooking the River Sealy. While he initially hunted the local badgers, otters, and polecats with Otterhounds and terriers of indeterminate pedigree, he grew dissatisfied with their abilities, and became determined to develop a breed of his own. His stated aims were to create a terrier of small stature, white in colour (to distinguish it from its prey), and with a strong jaw, and his breeding efforts began in 1848.

Unfortunately, he kept no written records of his breeding programme, but it is believed that another Pembrokeshire native, the Pembrokeshire Corgi, was instrumental in creating the longer back that was desired. Several other breeds, including the West Highland White Terrier, the Dandie Dinmont, and the Bull Terrier contributed to the final genetic make-up of the Sealyham. Though clearly a determined man, it is difficult to see Captain Tucker-Edwardes as a dog lover, for he was known to be quick to shoot those dogs that shied away from pursuing their quarry.

The Sealyham Terrier was recognised as early as 1911 by the Kennel Club, and became extremely popular with celebrities in the early days of Hollywood, sparking a great deal of public interest in the breed. In 1959, a British newspaper published a story that Princess Margaret would refuse her breakfast in bed each morning if her two Sealyhams were not brought to her at the same time. Despite making such an impact in high society, the breed suffered a drastic decline in popularity in the ensuing decades, and is now a rare one.

In 2008, only 43 pups were registered, representing an all-time low; however, the most recent figures from the Kennel Club show a slight improvement over the intervening years, with 113 new entries for 2016. Unfortunately, this is still below the critical level of three to five hundred thought to represent a diverse and healthy breeding population. The Sealyham retains a strong appeal for many within the confines of the show ring, and has won the prestigious Best in Show title at the Westminster Kennel Club Dog Show no less than four times, with its only victory in Crufts coming in 2008.


Sealyham Terrier Large Photo

The Sealyham Terrier is an active, alert little dog, of considerable strength and substance. Its head is long, broad and slightly domed between the ears, and has a subtle indentation that runs down between the eyes. The shape of the square muzzle is often accentuated by the way in which its hair is clipped. The nose should be black and have large nostrils. It has a strong bite, with particularly well-developed canine teeth. The eyes are slightly oval in shape, very dark, and set wide apart and deep in the sockets, to provide protection from scratches and bites. The medium-sized ears are wedge-shaped, with rounded edges, and are folded forward to the side of the head.

The Sealyham’s body proportions are quite distinctive: as well as its long skull, it has a neck that is around two-thirds as long as the dog is tall. These two features combine to give the dog great reach when straining to get down a burrow or into a narrow space. The back is relatively short and stocky, but the breed is remarkably supple nonetheless. The chest is well let down between the forelegs with good spring.

The limbs are short and strong with good bone structure. Though both fore and hind limbs are set wide apart, due to the breadth of the chest and heavy muscling of the thighs, they should be straight and true when in motion and viewed from the front. Equally, the small, cat-like paws should be turned neither in nor out when standing. There is good angulation at the shoulder and stifle, allowing this little dog plenty of power and acceleration.

When left untrimmed, the Sealyham Terrier has a long, coarse topcoat, with a soft and dense undercoat that is weather-resistant. Many are all white in colour, but lemon, brown, blue, and badger markings are permitted around the face and ears. Black markings occasionally occur, but are not viewed favourably. As a terrier bred to go to ground, excessively long limbs are discouraged, and the breed standard does not specify a minimum height. Instead, both males and females must be less than 31 cm (12 in) tall at the withers, or the top of the shoulder blades. Males should ideally weigh around 9 kg (20 lb), and females 8 kg (18 lb).

Character & Temperament

As a long-time terrier owner myself, I would be among the first to admit that they are not always the easiest dogs to live with, given their propensity for stubbornness, barking, and relentlessly attacking the vacuum cleaner whenever it appears. The Sealyham, however, is a more laid back character than most of its terrier cousins.

Sometimes described as couch potatoes, they are calm and confident dogs, very affectionate toward their owners, and willing to accept the company of other dogs without complaint. Indeed, with their background as hunting dogs, they enjoy being part of a pack, and will even take to cats and other smaller pets, particularly if raised with them.

Though young children must be taught how to approach and handle dogs in an appropriate manner, it would take quite some provocation to elicit a bite from a Sealyham, and so they are a good choice of pet for families. They are sociable and inquisitive dogs, and will befriend visitors to the home rather than being standoffish and suspicious. However, although they generally lack aggression, they have enough terrier spirit to make good watch dogs, willing to bark when needed.


Photo of Sealyham Terrier puppy

Sealyhams are clever, alert dogs that can learn a good repertoire of tricks and commands. However, for all their good points, they remain terriers, and are capable of being stubborn, selectively deaf, and easily distracted. Training sessions need to be kept short and stimulating, with plenty of positive reinforcement in the form of encouragement and the occasional treat.

Early socialisation of puppies is important for every breed, and young Sealyhams must be given the opportunity to meet new people and animals in a range of settings as soon as their primary vaccination course has been completed.


Health problems are very uncommon in the breed, especially for dogs coming from a healthy line. Because of the small population of Sealyhams at the present time, it is extremely important that anyone considering the purchase of one of these little dogs research their breeders carefully. As eye problems are the most common issue for the breed, prospective owners should insist on seeing certificates of ocular health for both puppies and parents.

Atopic Dermatitis

Like many other terriers, the Sealyham is prone to this form of allergic skin disease, in which a hypersensitivity reaction to allergens absorbed through the lungs and/or skin results in intense itching and skin irritation. The ears, feet, and perineum are the areas most often affected. Common allergens include house dust mites, plants and pollens, and even other pets.

Though the condition is incurable in most cases, there is a huge range of treatments available that can help manage it and make the pet more comfortable.

Congenital Deafness

Sealyham pups are occasionally born deaf, which is usually noticed by owners at around six weeks of age, when puppies become more responsive to the sounds in their environment.


The breed’s large head can cause problems in the birthing process, with the result that quite a lot of Sealyhams are born by Caesarean section. Inexperienced breeders must educate themselves as to the stages of labour and its expected progress, and should contact their veterinary surgeon at an early stage if they feel that their mum-to-be is experiencing difficulties.


Sight loss and ocular pain due to increased pressure within the eye is relatively common in the breed, but is most commonly caused by lens luxation, which is discussed below. Squinting, enlargement of the affected eye, and changes in behaviour are the signs most often noticed by owners.

Lacrimal Punctal Aplasia

As anyone who has ever cried will realise, there is a tear duct located at the medial corner of the eye that carries tears from the surface of the eye into the nose – hence the running nose that accompanies a good bout of sobbing. In some Sealyham Terriers, the entrance to this duct does not develop, with the result that tears overflow onto the face.

In most cases, this is simply a cosmetic issue, as it causes staining of the hair around the eyes. Occasionally, chronic dampness can cause skin infections, so it is a good idea to regularly clean this discharge away with a very mild antiseptic solution.

Lens Luxation

This is a common problem in many terriers, in which the fibres that suspend the lens in its normal position within the eye degenerate and weaken. As a result, the lens can fall into one or other of the eye’s chambers, potentially causing glaucoma (above) and loss of sight.

This most commonly occurs in middle-aged dogs, and if not recognised and treated promptly, can cause permanent loss of vision. There is a DNA test available to identify individuals at risk of lens luxation, and this should ideally be used to remove affected and carrier dogs from the breeding population.

Retinal Detachment

This is another disorder affecting the eye, which usually results from trauma, such as a traffic accident. The retina, the delicate layer of nerve cells at the back of the eye responsible for vision, can become dislodged from its underlying attachments by blood or other fluids, usually resulting in permanent sight loss.

Exercise and Activity Levels

The Sealyham enjoys its walks, but rarely demands them. With access to a small outdoor space, most will get the majority of their exercise in the form of rooting through flowerbeds in search of rodents or insects. Lead walking for at least half an hour every day is the minimum requirement for any healthy dog, as it provides an opportunity to develop the bond between dog and owner, as well as teaching good manners and obedience.


When regularly groomed and trimmed, the Sealyham can look neat as a pin. However, the opposite is also the case, as its wiry coat is prone to tangles, and will grow quite long if allowed. For owners not wanting to clip the coat short, brushing at least three times a week is required, with hand stripping of dead hair, which amounts to quite a lot of work. A better option for many owners is to have their dog professionally groomed every six to eight weeks, which makes the hair much easier to manage.

Famous Sealyham Terriers

In its heyday, the Sealyham was to be found at the feet of some of its most famous human contemporaries, including:

  • Cary Grant
  • Bette Davies
  • Elizabeth Taylor
  • Humphrey Bogart
  • Princess Margaret
  • Agatha Christie


The Sealyham is such a rare commodity that it is not often cross-bred, though the Sealydale Terrier, the result of crossing it with an Airedale Terrier, is sometimes seen for sale.

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