| Country of origin: | Wales |
| Registries: | AKC, UKC, CKC |
| Occupation: | Hunter, companion |
| Size: | 8–9kg (18–20lb), 25–30cm (10–12in) |
| Longevity: | 14 to 16 years |
| Exercise: | Moderate |
| Training: | Challenge |
| Grooming: | Difficult |
| Colors: | White |
The Sealyham was developed in Britain from a range of terriers. The aim was to produce a small, powerfully built dog that would take on otters and badgers above ground, below ground, and in water. It excelled in this role, and was an immensely popular dog in the early 20th century. Today, redundant from the job it was originally bred for, the Sealyham is seldom seen, and has made the transition to the show ring with only partial success. Although their spirited personalities are attractive and they make good watchdogs, these dogs tend to be territorial and often aggressive towards other dogs. Males in particular can be a challenge to train. The dog’s wiry coat is kept at its best by stripping, which may need to be done professionally.