The canine skin and coat

Your dog’s skin and coat make up a multi-functional super system. They are a barrier of protection, a convenient thermostat and water meter, as much as they are a barometer of your dog’s internal health. Your dog’s skin and coat also function as his largest sensory organ, as well as a very important communication tool.

In this article, we’ll explore the structure and function of the canine skin and coat. We’ll suggest ways to keep your dog’s skin and coat healthy, discuss the symptoms of an unhealthy skin and coat, issues that may arise and when to see the veterinarian as a result.

The structure of the skin and coat

When we refer to your dog’s skin, we’re talking about the entire organ that covers his body, making up around 12% of his body weight. Most areas of a dog’s skin are covered in fur, which can be thicker and longer in some areas (like the scruff of the neck, the ridge of his back and at the feathering at the backs of the legs) and shorter and thinner in others (like on the belly). Understanding the structure of the skin and coat will help owners to understand their function and make better decisions about skin and coat care, and grooming. 

Structure of your dog’s skin

Your dog’s skin is made up of the epidermis (outer layer), dermis (middle layer), and hypodermis (inner layer) or subcutaneous layer.

  • The epidermis helps to protect the sensitive dermis, and to stop the skin from drying out or your dog losing water via his skin. It produces keratin (from keratinocyte cells) and includes nails and fur.
  • The dermis comprises your dog’s collagen layer and contains the hair follicles, skin oil (sebum), and sweat glands.
  • The hypodermis or subcutis (literally ‘under skin’) or subcutaneous layer consists of blood vessels, nerves, and a layer of fat. The blood vessels feed the skin with nutrients and oxygen, while the layer of fat has an insulating effect. The hypodermis connects the skin to your dog’s muscles. 

Structure of your dog’s coat

Your dog’s skin houses his fur coat, which is made up of tens of thousands of central and secondary hairs. Most dogs have a double coat, which consists of a fine, soft, downy, insulating undercoat and a topcoat of longer guard hairs that are thicker and coarser than the undercoat. This undercoat is a feature of working breeds like collies and shepherds, Rottweilers and retrievers, who needed a layer of insulation from the weather as well as a protective layer to guard them from injury. When your dog sheds, it’s this undercoat that is ejected once or twice a year when he doesn’t need as much protection from the cold.

Some dogs have a single coat that grows continuously and needs frequent trimming. These include dogs like the Yorkie, shih tzu, short-coated Chihuahua, poodle, short-coated dachshund or the saluki (among others).

Then there are the cold-warriors that have a triple coat, which consists of two identifiable insulating undercoats as well as a topcoat of thick guard hairs. These dogs are often genetically closer to landrace dogs that evolved to withstand extreme near-polar weather, and include breeds like the Alaskan Malamute, Siberian husky, chow-chow, Samoyed and Pomeranian (all spitz-type dogs).

Then there are those genetically mutated dogs with no coat at all – like the Mexican hairless dog (Xoloitzcuintli), American hairless terrier and Peruvian hairless dog (Peruvian Inca Orchid) – or just little tufts of fur, like the Chinese crested. Hairless breeds also have their special place in the dog world, but extra care needs to be taken to feed, clean and protect their skin.

What is the purpose of a dog’s skin?

A dog’s skin has a range of functions:

  • Protective barrier: Protection from the elements as well as from external injury.
  • Immunity: Related to protection, the skin is the first barrier to infection and is part of the immune system that detects invasive bacteria, fungi and viruses.
  • Water retention: Dogs need to maintain their hydration levels. Aside from their drinking enough fresh water, the skin helps them to not suffer from water loss. Dry, flaky, unhealthy skin is prone to water loss, which can result in a range of other health problems.
  • Internal communication: Nerves in the skin tell your dog whether he’s hot, cold, in contact with an object or experiencing pain.
  • Source of nutrients: A dog’s skin serves as the temporary storage site of certain proteins, vitamins and minerals. When – for example – vitamin D precursors in the skin are exposed to sunlight, they convert to usable vitamin D in the body. Antioxidants like vitamins A and E are stored in the skin and used to maintain cells and protect the skin itself. Omegas-3 and 6 are also stored in the skin and work as anti-inflammatories when necessary for a dog’s wellbeing.

What is the purpose of a dog’s coat?

  • Protection: Whether wire-coated dogs being protected from thorns in the underbrush, to thick-coated dogs being protected from predator bites, a dog’s coat offers protection from injury, UV rays, foul weather, and harmful substances.
  • Thermoregulation: A dog’s coat has the special quality of helping to balance a dog’s body temperature. Whether insulation from the cold or protection against heat, thermoregulation is one very good reason to never shave a double- or triple-coated dog. They manage their body temperature in the summer and release body heat by panting and finding a cool, shady spot in which to lie down.
  • External communication: Your dog’s coat can tell other animals to come closer or back off. His raised hackles (called piloerection) are very good way to communicate emotional arousal (not necessarily aggression). This sympathetic nervous response is caused when the hair follicles contract and the hair stands on end.
  • Aesthetic distinction: In the world of dog showing, dogs’ coats are one of the standards upon which conformation is judged. While there is no biological reason for this purpose for a dog’s coat, it is one of the motivations for breeding dogs and a determining factor in selective breeding development.

How to keep a dog’s skin and coat healthy

Now that we’ve covered the form and function of the canine skin and coat, it’s important to note that there are many things dog owners can do to keep our dogs’ skin and fur healthy.

Keep your dog’s skin and coat healthy with good nutrition

What food is good for dogs’ skin and coat? Since dogs’ skin structure is mostly made up of proteins (collagen and keratin) and fatty acids, it’s crucial to feed your dog with a scientifically formulated dog food that contains high-quality proteins and the right balance of omega-3 and -6 fatty acids. A blend of high-quality ingredients – including carbohydrates and fibre – should help to keep your dog’s skin nourished, supple and able to function properly. Your dog’s nutrition should also contain the optimal blend of vitamins and minerals, which support skin and coat health as well as the health of all his other bodily systems. If his entire body is optimally fed, his skin and coat will be healthy too.

Support your dog’s skin and coat health with supplements

Some dogs need additional skin-nourishing supplements, which contain a concentrated formula of EPA and DHA (omega-3s), zinc, linoleic acid (omega-6) and B vitamins. These all help to keep the skin moisturised and the coat looking shiny and healthy.

Groom your dog’s coat and moisturise his skin

Grooming is an essential part of good dog ownership. Even if your dog is not a dumpster diver, doesn’t roll in objectionable substances, and keeps far away from mud, it’s important to regularly brush his coat and keep and eye on his skin. How often should you wash your dog? Well, that depends on the dog. Some dogs have short coats and pretty oily skin and need regular baths; while other dogs have easy-care coats that could do well with a weekly brush and a bath about three times a year. Most dogs need a bath every one or two months, but check this with the vet. If you bath your dog too often, it could dry out their skin, which could become itchy, flaky and susceptible to infection.

Keep your dog’s parasite control regimen up to date

Whether you give your dog an internal tick and flea medication (such as chews or tablets) or whether you apply a spot-on treatment for ticks and fleas, make sure you apply the medication at the recommended intervals. External parasites can trigger pain and itching, which can set off a chain of scratching and infection. A healthy skin and coat are no place for pests!

If you’re concerned about your dog’s coat and skin, speak to the vet about a good skin and coat care regimen. If his skin is very oily or very dry, the treatment will vary, so only the veterinarian can advise you correctly on the ideal healthy skin solution for your dog.

Symptoms of illness in your dog’s skin and coat

Since your dog’s skin and coat are so closely connected to other organs and systems in the body, this is one of the first places where symptoms of imbalance will show up. Some of the skin and coat symptoms you might observe with an unhealthy dog include:

  • dandruff, flaky skin (associated with hormone imbalance or digestive upset)
  • extremely dry skin (associated with kidney disease)
  • itchiness and inflammation (associated with ticks and fleas, or food allergies)
  • hotspots (associated with anxiety or pain-relief behaviour)
  • excessive shedding (associated with high stress or allergies)
  • patchy fur (associated with mange, fungal infection, inflammation and chronic scratching)
  • formation of hard, dry calluses – hyperkeratosis (associated with chronic liver disease, or ageing)

Sometimes dogs simply have a genetic predisposition to dry, itchy skin and/or allergic reaction to food or environmental allergens. It’s important for your dog’s wellbeing that these symptoms be managed with diet, medicated shampoo, and/or removing him from allergy-triggering environments; even if it’s for the rest of his life.

When should you see a vet about your dog’s skin and coat?

Any skin and coat symptoms that appear on your dog should immediately be checked out by the veterinarian. Because the skin and coat are affected by so many of your dog’s organs and body systems, it can be difficult and time-consuming to diagnose the underlying cause of the symptoms.

Keep a record of when the symptoms started. Do they flare up during a particular season? (Could be due to environmental allergies.) Do they flare up after your dog eats? (Could be due to food allergies.) Have the symptoms been getting progressively worse? (Could be due to a chronic illness.) Maybe there’s a genetic component to a worsening skin condition. The vet can perform blood tests, intradermal testing or a skin-scrape to find the culprit in your dog’s skin and coat symptoms.

It's impossible for the vet to try to determine the cause of poor skin and coat condition without performing a physical examination and receiving information about his diet, lifestyle and behaviour, so make an appointment if you have any concerns about your dog’s health.

How can I improve my dog’s coat and skin? Once you’ve received a diagnosis and/or a recommendation, follow the vet’s advice to the letter. At-home compliance with veterinary advice is critical in ensuring your dog’s condition improves and his wellbeing is restored.


One of the first indicators of a healthy dog can be found in his smooth, hydrated skin and shiny coat. He just looks full of vitality and health. Keep him well-fed and regularly groomed, and if you notice any symptoms of dry, flaky, itchy skin, take your dog to the vet for a check-up, advice and treatment, where necessary.

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