A balanced diet, as well as supplementation with a variety of essential nutrients, is crucial when it comes to treating canine skin diseases.
Canine skin diseases are common in pet dogs and can result in significant discomfort, itching, inflammation, secondary infections, and hair loss. Proper nutrition plays an important role in maintaining healthy skin and coats in dogs, and can aid in the management of skin diseases.
The skin is the largest organ of the body, and the second largest part of the immune system. It plays a crucial role in protecting against external factors such as infections and harmful substances. It also helps regulate body temperature and hydration levels. Along with genetics, age, and environmental conditions, the health of a dog’s skin and coat depends on a balanced diet and the presence of certain essential nutrients.
NUTRIENTS ESSENTIAL FOR SKIN HEALTH
To maintain healthy skin, dogs need a balanced diet that provides important nutrients, including proteins, fatty acids, vitamins, and minerals. Supplementing specific nutrients beyond their normal daily requirement can be helpful in the management of some skin diseases.
- Polyunsaturated fatty acids (PUFAs) are essential fatty acids that must be provided through diet in the form of Omega-3s and Omega-6s. PUFAs help reduce inflammation, hydrate the skin, and prevent skin infections by maintaining a healthy skin barrier via the epidermal lipid barrier.1
The Omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are available in high concentration in fish oils and are immediately usable for dogs. Plant-based sources of Omega-3 fatty acids, such as flaxseed oil, contain alpha-linoleic acid (ALA) which needs to be converted to EPA and DHA for utilization. Dogs and cats do not convert ALA to EPA/DHA. The amount of ALA needed to reach therapeutic levels of EPA and DHA in the dog can cause gastrointestinal upset and lead to excessive caloric intake.
Beyond a doubt, the most common skin diseases managed by general practitioners are the inflammatory skin diseases of flea allergy dermatitis, atopic dermatitis, and adverse food reactions (food allergies and food intolerances). It is generally now well accepted that supplementing Omega-3 fatty acids can help reduce inflammation and pruritus in these patients. Current dosing recommendations are found in Table 1.
Omega-6 fatty acids, linoleic and arachidonic acids, are also required for skin health. However, the addition of Omega-6s beyond the recommended daily requirement for health does not appear to play a significant role in the management of skin diseases.
- Vitamins A, B complex, C, D, and E all play important roles in maintaining healthy skin and coat in the dog.
- Vitamin A helps maintain skin hydration, regulates skin cell growth and differentiation, and plays an immunomodulatory role. It may be helpful in the treatment of seborrhea in certain breeds, and was shown in a case report to play an essential role in the management of a dog with severe seborrhea when given in high doses.2
- B complex vitamins, including B1, B2, B6 and B12, are important for the formation and maintenance of healthy skin cells. As with Omega-6 fatty acids, B-complex vitamins given in excess of the daily requirement may not be beneficial for skin disease management. However, additional B vitamin administration is needed to maintain healthy skin when absorption is reduced.
- Vitamin C is necessary for the production of collagen. Additionally, it is an antioxidant that can protect skin cells from free radical damage.
- Vitamin E is another antioxidant essential for skin health. It plays an important role in maintaining the skin barrier. Vitamin E supplementation is often recommended in the management of autoimmune skin diseases such as varieties of pemphigus, vasculitis, and lupus, as well as inflammatory skin disease caused by allergies and food intolerances.
It is important to note that vitamins A and E are fat-soluble, so supplementation beyond what’s naturally found in whole foods should be done with foods containing fats. Additionally, excess fat-soluble vitamins can be stored in body fat and cause toxicity when given chronically at very high doses.
B-complex and C vitamins are water-soluble so can be given with or without food. High doses are much less likely to lead to toxicity. However, this is no evidence to suggest that very high doses of B vitamins or vitamin C are beneficial to skin health.
- Zinc and copper are minerals that both play important roles in skin health and specific skin diseases.
- Zinc is important for the growth and repair of skin tissue and the maintenance of healthy skin. While dietary deficiencies are uncommon when dogs are fed a properly balanced diet, hereditary zinc-responsive dermatoses, as seen in many arctic/Northern breeds, require additional zinc beyond the minimum recommended amounts (see Table 1).
- Copper should not be fed in excess; however, copper deficiency can lead to dry, discolored, brittle hair and alopecia.
Severe skin disease is often a symptom of underlying internal organ or endocrine dysfunction, and may require significant diet supplementation. A case report from the University of Missouri Veterinary Health Center demonstrated significant skin health improvement in a dog with superficial necrolyticdermatitis (aka metabolic epidermal necrosis, hepatocutaneous syndrome) using a nutritionally-balanced, home-prepared diet high in quality protein, lysine, and vitamins A and D. While it was unclear which factors of the diet contributed to the patient’s improvement, it was clear that the diet was an essential element of the treatment protocol.3
WEIGHT CONTROL CAN BE IMPORTANT
Beyond a balanced diet and the additional supplementation of certain PUFAs, vitamins, and minerals, maintaining a healthy weight may be important in managing some canine skin diseases. The link between obesity and several skin conditions, including the inflammatory condition of psoriasis, has been established in people. 4 It has been postulated that obesity may contribute to skin disease by increasing inflammation and altering hormonal levels in the body. The impact of obesity on skin diseases in dogs has yet to be fully explored, but weight control should be considered an important part of management until further information is available.
COMMERCIAL OR HOME-PREPARED FOOD?
A discussion about the effects of nutrition on canine skin diseases should not exclude the controversies around feeding processed commercial pet foods versus home-prepared diets. When adverse food reactions are suspected, a food trial in the form of a commercial novel protein/novel carbohydrate or hydrolyzed diet is often recommended. Commercially-prepared diets, while convenient and generally balanced with essential nutrients, come with certain challenges:
- Unless the diet is “prescription”, most over-the-counter limited ingredient diets are contaminated with or contain ingredients not on the label, the effects of which are undetermined.5
- There is little to no information available on how (and where) ingredients in commercial foods are farmed or harvested. Sensitivities to chemicals contained in or on individual ingredients within a diet could appear as an adverse food reaction.
- Many prescription limited ingredient diets and hydrolyzed diets are extremely expensive, with a 20 lb bag of dry kibble easily exceeding $100.
- There are limits to the available ingredient options, many of which are now routinely added in regular maintenance diets.
- Hydrolyzed diets can contain protein pieces large enough to still stimulate an immune response.6
Home-cooking, using balanced recipes, can provide solutions to many of the challenges presented with commercially-prepared foods:
- Ingredients can be tightly controlled and easily changed.
- Organic and/or local ingredients can be used and inspected by the client, and responsibly sourced.
- As long as a client has access, a huge variety of ingredient choices is available.
- One study found that feeding a commercial dry diet for chronic enteropathies was less expensive than feeding a similar home-prepared diet with similar ingredients.7 But because of the wider ingredient options available, it can be less expensive to home-cook than to purchase prescription foods.
The main challenges in feeding nutritionally-balanced, home-prepared diets largely relate to client compliance. Namely, ensuring proper ingredient measurement, cooking ingredients according to instructions, avoiding changes to the diet without rebalancing it, and consistent and persistent use of the correct supplements to safely balance the diet.
When it comes to preventing adverse food reactions, considerable research in the human literature indicates that a varied diet early in life reduces the risks of atopy and the development of food allergies.8
Canine skin disease is a common presentation in general small animal practice and can cause a significant impact on patient and client life quality. Nutrition plays a critical role in the management of skin disease by providing essential nutrients, controlling weight, and improving the skin barrier. Food therapy using Chinese medicine principles can also improve skin health and reduce the risk of skin disease. By providing a balanced and nutritious diet and incorporating theories of food energetics, owners can help maintain the health and integrity of their dogs’ skin while reducing the use of medications that can be costly and have adverse effects.