What To Know About Sealyham Terriers

Medically Reviewed by Vanesa Farmer, DVM on June 13, 2022
Written by Alyssa Anderson
7 min read

Sealyham terriers are outgoing, humorous dogs in the terrier group. 

They’re compact, sturdy workers but are just as happy curled up at home with their families. Just make sure that you can take them outside and provide for all of their needs before choosing to make one a member of your family. 

Body size. Sealyham terriers are small dogs. Their average height is about 10.5 inches. Healthy dogs should weigh an average of 23 to 24 pounds. The females may be slightly shorter or smaller. 

Make sure to talk to your veterinarian if you’re concerned that your dog is overweight. 

Their small size means that these dogs are very comfortable in both small apartments or out in the country. They’re also incredibly portable and will enjoy exploring the world with their families. 

Body shape. Sealyham terriers are some of the strongest and most substantial of the small dogs. They have well-muscled bodies that run low to the ground. 

They have long, broad heads with slightly domed skulls. These are topped by thin, folded ears that are well-rounded at the tip. 

Terriers have tails that are set relatively high on their spines. Some owners dock them, but this is never recommended by veterinarians.

Lifespan. The Sealyham terrier lifespan is normal for their size. On average, they live anywhere from 12 to 14 years. This means that you should plan on spending over a decade with your pet, especially if you adopt them when they’re a puppy. 

Coats. Sealyham terriers have weather-resistant double coats. Their double coat means that your dog makes two distinct types of coats, each with its own properties. 

Their undercoats are soft and dense. The outercoats are hard and wiry. They’re grown to a medium length. 

All their coats are white, so the only Sealyham terrier colors come from their markings. The markings can come in four different colors: 

  • Lemon 
  • Black
  • Tan
  • Badger

Eyes. These dogs have deeply set, dark eyes. They’re set a decent distance from one another and are medium-sized and oval-shaped. 

Personality. The Sealyham terrier personality is outgoing and alert. They also have a strong sense of humor. They’re hardworking when on the hunt and are delightful companions at home. 

The Sealyham terrier temperament is brave and fearless. They shouldn’t be too shy or overly aggressive.

These dogs have lots of energy but should never become too hyperactive if they’re given proper training and attention. 

Grooming. Sealyham terrier grooming is moderately difficult. How often you have to groom them, though, depends on how long you choose to keep the fur on their bodies and legs. The longer the fur, the more often you’ll have to groom them.

Their coats can form mats easily, so brush them at least every two to three days. You should also bathe them at least once a month. 

You should clean their ears and trim their nails regularly. Brush their teeth every day with a dog-safe toothpaste to complete their grooming routine. 

Feeding. Make sure that your pet has access to clean water at all times. 

Your Sealyham terrier should be fed with high-quality dog food. Try to find a brand that your pet enjoys. Make sure that the nutritional requirements are specific to their stage of life, including puppy- and senior-specific foods.

One consideration for these dogs is that dyed food can sometimes stain their beards. This can turn their normally white coats yellowish and may not be desirable. Stick to brands that don’t use dyes to avoid this problem. 

Always consult your veterinarian before choosing to make an at-home blend for your dog. Making your own food can be a complicated process. You need to make sure that you’re meeting all of your dog’s nutritional requirements. 

Also, make sure that you know what human foods are safe for your dog to eat before feeding them anything from your kitchen. 

Exercise and Mental Stimulation. Exercise is necessary for both your Sealyham terrier’s physical and mental health. 

You should get them outside every day so they can run around and wear themselves out a bit. This will keep them calmer and easier to manage when they’re indoors. They’ll be happier pets as well. 

Just make sure that they don’t exhaust themselves. These dogs overheat easily and are best let out early in the morning or later at night. Keep in mind that they can develop grass stains easily, but this shouldn’t keep you from exercising them outside. 

Veterinary visits, medications, and immunizations. Your veterinarian is the best person to determine all of the vaccinations that your pet needs, but all dogs should get a core set. This includes vaccinations for:

These can begin as early as six weeks of age. There are also other non-core vaccinations that you can discuss with your veterinarian. 

Dosages for flea and tick medications are based on your dog's weight and used as needed. Oral and skin-based applications are available from your veterinarian or other distributors. Heartworm medication is also recommended year-round in all parts of the United States.

Many medications can be effective against a variety of pests and parasites, so talk to your veterinarian to figure out the best one for you. 

Sealyham terriers can have a number of different health conditions — both those that they’re born with and those that can develop throughout their lifetime.

Common Sealyham terrier health conditions include: 

  • Eye conditions. These dogs can be affected by a large number of eye conditions, including ones that can lead to blindness like cataracts, glaucoma, and progressive retinal atrophy (PRA). With PRA, you may start to notice your dog struggling to see at first, particularly at dusk and dawn. At present, there isn’t a treatment for this condition. They can also contract dry eye and primary lens luxation (PLL) among other eye conditions. PLL is an inherited condition that can cause your dog’s lens to loosen and create secondary complications. You should have your dog’s eyes examined regularly to detect any of these eye conditions. 
  • Allergies. Allergies to dust, mold, and pollen can make your dog’s skin itch. Symptoms usually appear within your dog’s first three years of life and can get worse each year. Your dog may rub their face, lick their paw, or develop frequent ear infections when they have allergies. There are many different treatment options depending on the extent and location of the allergies. 
  • Intervertebral disc disease (IVDD). This is a condition where one or more of the discs in your dog’s spine starts to press against the spinal cord. It causes a lot of pain, so your dog may be unwilling to go upstairs or walk around and could develop a hunchback. Surgery is needed in severe cases, but milder ones can be treated with medications and weight loss. 
  • Mange. Small mites live in the coats of all dogs. Most breeds are able to keep them in check, but they can become problematic in the Sealyham. Look for dry, irritated, and hairless patches on their skin. Your veterinarian can treat this condition, but you should get them help as soon as possible, or the condition can get out of hand. 
  • Degenerative myelopathy. This is a neurological condition that makes your dog’s back legs weak. It eventually leads to complete paralysis and incontinence. There isn’t a cure, but there are ways to manage your dog’s symptoms. 
  • Idiopathic epilepsy. This is a condition where your dog can have unexplained seizures. If they do, get them to the veterinarian as soon as possible.
  • Deafness. This is a heritable condition, so pay attention to your pet when they’re young to see if they listen to you. Have your veterinarian check them out as soon as you notice any problems. The condition could be a serious ear infection that requires immediate treatment.  

Sealyham terriers run the risk of becoming an overly aggressive breed without early training and socialization. The AKC only rates them a three out of five for their ability to interact with small children and other dogs. 

Consequently, you should expose them to as many people, dogs, and situations as you can from a young age. This will make them more comfortable with a variety of circumstances. 

They also make for great watchdogs. The AKC rates them a five out of five for this trait. 

They have a big-dog bark and they do like to use it. Keep their loud, insistent bark in mind before bringing one home. 

They shed a moderate amount but rarely drool. 

The Sealyham terrier is named after the Welsh estate where they were bred. The estate belonged to Captain John Edwards and was called Sealy Ham, at Haverfordwest, Wales. Captain John Edwards retired from the military at the age of 40 and spent the rest of his life breeding dogs. 

Unfortunately, he didn’t keep notes on the breeds that he used to create the Sealyham. Experts believe that he could have used a number of different breeds, including: 

  • Corgis
  • Dandie Dinmonts
  • West Highland whites
  • Wirehaired fox terriers
  • Bull terriers
  • Possibly some hound varieties

Regardless of what breeds he used, Captain John Edwards created these dogs with a particular task in mind. They were specifically bred to work with his otterhound packs to rid his estate of these nuisances. At this time, otters were considered as pesky as gophers because they would steal fish from estate ponds.

These dogs can actually dig otters out of their underground burrows. They’re also great at extracting badgers and foxes. 

The breed was added to the English Kennel Club in 1910. They were first imported to the U.S. in 1911. 

They reached their heyday between the first and second World Wars. They won the Westminster dog show three times during this period and were owned by celebrities like Humphrey Bogart and Cary Grant. 

Their popularity has gone down since then, but Sealyham terriers are still frequently used as therapy dogs in children’s hospitals and nursing homes.