A lustrous coat signals vitality and can indicate the health status of a pet. Pets with a dry, flaky, or unkempt coat may be suffering from conditions such as thyroid disease, hyperadrenocorticism (Cushing's disease), kidney or liver disease, or nutritional disorders (for more information on these conditions and how they can affect your pet's skin, see the specific handouts, as well as "Coat and Skin Appearance in the Healthy Dog" and “Coat and Skin Appearance in the Healthy Cat”). In fact, one of the main ways your veterinarian assesses the health of your dog or cat is by looking at the condition of her coat and skin.
What do I need to know about my pet’s skin and coat?
The skin and coat form the largest organ in dogs and cats, comprising around 10% to 15% of their total body weight. The skin is made up of the hypodermis (layer under the base layer of 'skin') which contains mostly fat, the dermis, and the epidermis.
The dermis is made up of collagen and is the largest portion of the skin. The dermis is also the most metabolically active and contains the sebaceous glands and hair follicles. Sebum, the oily substance secreted by the sebaceous glands, keeps the skin and hair lubricated and also coats the hair to prevent friction during movement.
The epidermis contains specialized skin cells called keratinocytes which produce keratin - a waxy substance that covers the epidermis to prevent the loss of water through the skin.
Your pet's coat consists of thousands of hairs produced in hair follicles. Because hairs are under constant environmental stress, they are continuously shed and replaced. Anyone who has ever cleaned up after his or her pet can attest to the volume of hair shed each day! Seasonal shedding, which also occurs to replace the coat, is affected by the outside temperature and hours of daylight each day (the photoperiod). However, cats and dogs who spend much of their time inside, exposed to a more consistent climate and electric light, may shed year-round.
What roles do my pet’s skin and coat play in his health?
Besides being pretty to look at, your pet's skin and coat play vital roles in their health; they functions as an important part of the immune system and are critical to maintaining proper hydration. The following are some of the basic functions of the skin and coat:
- Protection. The skin and coat provide a barrier that protects a dog or cat from external objects, chemicals, and environmental stressors. In simplest terms, the skin and coat protect the internal organs from external threats. The skin also contains nerves and nerve endings that help a pet sense heat, cold, pressure, and pain. Additionally, the coat protects pets against chemical damage, trauma, ultraviolet light, and contact with hot surfaces.
- Immunity. The skin also functions as an important part of the immune system. If the skin's immunity is compromised, infections and potentially serious diseases caused by harmful bacteria could occur.
- Thermoregulation. A healthy coat helps keep a pet's temperature properly regulated by providing an insulating layer of fur. A healthy coat can efficiently regulate body temperature by moving hair follicles to bring hairs closer together to insulate or allow air to enter under looser hairs to cool a dog or cat. A pet can also warm herself by shivering.
- Hydration. You may not realize it, but your pet's skin is critical in maintaining proper hydration. Water loss through the skin can severely impact your pet's health. Dogs and cats do not have sweat glands, so excess water loss through unhealthy skin (transepidermal water loss) often causes health problems. Excessive water loss through the skin also affects the amount of energy a pet needs to maintain his metabolism.
- Nutrient storage. The skin also serves as a storage site for several nutrients. Protein and amino acids are present in the skin, as are collagen fibers and enzymes. Dog and cat hair is mostly made up of protein. Up to 35% of a dog's daily protein intake is used to maintain her skin and coat. Linoleic acid and other fatty acids are stored in the skin and are present in the phospholipid bilayer to provide flexibility and fluidity to the skin. Fatty acids are important in protecting pets against inflammation. The precursors to vitamin D are present in the skin and are converted to vitamin D by exposure to ultraviolet rays in sunlight. Minerals such as zinc, copper, selenium, and manganese are found in relatively high concentrations in the skin because of their role as cofactors and coenzymes in several biologic reactions that take place in the skin. Fat-soluble vitamins A and E may also be stored in the skin. Vitamin A is necessary for cell production and maintenance, and vitamin E is an antioxidant that helps protect the skin. B vitamins are found in the skin but are not stored there because they are water soluble.
How can I keep my pet’s skin and coat healthy?
Nothing affects the condition of your pet's coat more than his food. Diets rich in omega-3 fatty acids, protein, vitamins, and minerals play an essential part in caring for your pet's skin and coat.
- Omega-3 fatty acids (DHA and EPA) help protect the skin and coat and keep it shiny. EPA helps combat inflammation. Sources of omega-3 fatty acids include fish and algal oils and flaxseed.
- Linoleic acid, an omega-6 fatty acid found in corn, soy, flaxseed, and other nuts, is a key nutrient in maintaining a healthy coat. Many pets with dry, flaky skin are often deficient in linoleic acid. Dandruff, thin hair, discolored hair, increased shedding, and poor healing are all associated with low linoleic acid levels in the skin and diet.
- Zinc is especially important in the skin because of the high cellular turnover rate caused by constant shedding. In addition, zinc helps reduce water loss through the skin. Pets who are fed low levels of zinc develop hair loss, skin infections, and a dull appearance.
- Biotin and B vitamins play important roles as cofactors in many of the body's metabolic processes, including fat metabolism. This is important in the skin because biotin and B vitamins are involved in aiding linoleic acid function in the epidermis and dermis.
Recent research has shown that adding omega-3 fatty acids, linoleic acid, and zinc in combination increases coat gloss and decreases dry, flaky skin (dander).
Proper grooming can also help keep your pet's skin and coat in good shape. For information on grooming or bathing your pet, talk to your veterinarian and see the handouts "Grooming and Coat Care for Your Dog" and "Grooming and Coat Care for Your Cat."
What is my takeaway message?
The key to a healthy coat begins with your pet's diet. If you are concerned about how your dog or cat's coat looks, ask your veterinarian if an underlying nutritional or medical condition is to blame. With a clean bill of health and a proper diet, your pet will be well on his way to looking as good as any movie star dog or cat!