A lustrous coat is a signal of vitality and can be a quick visual indicator of a pet’s health. In fact, one of the main ways your veterinarian assesses the health of your dog or cat is by looking at the condition of their coat and skin. 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 about 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”.
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 composed of the dermis, the epidermis, and the hypodermis.
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.
The hypodermis is the layer under the base layer of skin that contains mostly fat.
Your pet's coat consists of thousands of hairs produced in hair follicles. These hairs are under constant environmental stress, so they are continuously shed and replaced. You might notice that some dog breeds appear to shed much less compared to others – poodles, for example. This decreased shedding occurs because the growing phase of the hair follicle is much longer in these breeds. It is also why some dog breeds like poodles have continuous hair growth and require regular grooming.
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 their health?
Your pet's skin and coat play vital roles in their health. Together, they function as an important part of the immune system, and they 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. 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 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 move hairs further apart (to cool). A pet can also warm itself by shivering.
- Hydration: Your pet's skin is critical to maintaining proper hydration. Dogs and cats do not have sweat glands, so excess water loss through unhealthy skin (trans-epidermal water loss) often causes health problems. Excessive water loss through the skin also affects the amount of energy a pet needs to maintain its metabolism.
How can I keep my pet’s skin and coat healthy?
The food your pet eats can have a dramatic effect on the condition of their coat. Diets rich in omega-3 fatty acids, protein, vitamins, and minerals help to care for your pet's skin and coat. Nutrients that have an impact include:
- Protein: Pet hair is mostly composed of protein. Up to 35% of a dog’s daily protein intake is used to maintain skin and coat.
- Linoleic acid: This omega-6 fatty acid is found in corn, soy, flaxseed, and other nuts, and is a key nutrient in maintaining a healthy coat. It is an integral component of cell membranes and helps to provide flexibility and fluidity to the skin.
- EPA and DHA: These omega-3 fatty acids help protect the skin and coat and also keep it shiny. These fatty acids also have anti-inflammatory properties and supplementation of additional EPA and DHA is often recommended for dogs with skin disease.
- Zinc: This mineral is especially important because of its role in cell division. Skin has a very high cell turnover rate, so a deficiency in zinc can result in a condition called zinc-responsive dermatosis. Arctic dog breeds have a hereditary zinc dermatosis condition related to a genetic mutation that affects absorption of zinc in the gut.
- Biotin and other B vitamins: These nutrients play important roles as cofactors in many of the body's metabolic processes, including fat metabolism. Biotin and B vitamins help linoleic acid function in the epidermis and dermis.
Aside from ensuring your pet is getting these important nutrients in their diet, proper grooming can also help keep your pet's skin and coat in good shape. For information about 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 the take-home 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 might be contributing. There are specific diets formulated with enhanced concentrations of some of the nutrients mentioned above that can help support skin and coat for pets that need more than what is included in a standard maintenance diet (for example, dogs or cats with food allergies).
Always consult your veterinary health team before making changes to your pet’s diet. Arbitrarily supplementing nutrients without your veterinary team’s guidance could unbalance the diet or lead to a nutrient toxicity.
