Skin & Coat Health Guide

Cause ① Dietary Allergens (Food Hypersensitivity)

• ✓Dietary allergies (food hypersensitivity) account for approximately 10–15% of skin disease cases in dogs. Hillier & Griffin (2001): the most common allergens are beef (36%), dairy (33%), wheat (15%), eggs (14%), and chicken (12%).
• ✓Dietary allergies can present as both IgE-mediated immediate reactions and non-IgE-mediated delayed reactions. Since symptoms can take hours to days to appear, identifying the causative ingredient is often difficult.
• ✓The gold standard for diagnosis is an 8–12 week elimination diet trial using a single-protein or hydrolyzed protein food. Mueller et al. (2016): during this period, treats and supplements must also be strictly controlled.
• ✓Allergies are rarely cured — avoiding the causative ingredient is the primary management strategy. Always check food labels for allergen presence with every purchase.

Cause ② Omega-3/Omega-6 Imbalance (Fatty Acid Deficiency)

• ✓The skin is the body's largest organ and requires a continuous supply of fatty acids. NRC (2006): EPA+DHA (omega-3) and linoleic acid (omega-6) are essential components of the skin barrier (ceramides and wax esters).
• ✓Omega-3 deficiency leads to dry skin, abnormal hair loss, dull coat, and increased dandruff. Adequate omega-3 also has anti-inflammatory effects that suppress skin inflammation and reduce itching.
• ✓The recommended omega-6:omega-3 ratio is 5:1 to 10:1 (NRC 2006). Some commercial foods exceed 20:1, in which case a fish oil supplement can help restore the balance.
• ✓Improvement takes time. Allow at least 6–8 weeks of observation after changing food before evaluating changes in skin and coat quality.

Cause ③ Zinc, Biotin & Other Micronutrient Deficiencies

• ✓Zinc deficiency causes zinc-responsive dermatosis. Hand et al. (2010): this condition is especially prevalent in northern double-coated breeds (Husky, Malamute) and rapidly growing large breeds (Great Dane).
• ✓Biotin (vitamin B7) is involved in keratin synthesis; deficiency causes coat deterioration, dandruff, and skin hyperkeratosis. Some raw ingredients (avidin in raw egg whites) can inhibit biotin absorption.
• ✓Vitamin A and E deficiencies can also cause keratinization disorders (seborrhea sicca/oleosa) and immune suppression. However, over-supplementation carries toxicity risks — stay within AAFCO (2023) guidelines.
• ✓Micronutrient deficiencies are largely preventable by feeding a complete and balanced food meeting AAFCO or FEDIAF standards. Home-cooked diets carry a higher risk of nutritional imbalance.