Flea saliva is very allergenic, so a single flea can cause flea allergy dermatitis (FAD) that makes your dog itchy at the bite site (often around the head, anus, neck, tail base, or groin area). In addition to the itching/scratching, dogs with a flea infestation will deposit flea “dirt” (or digested blood in the form of their feces) on the skin. This flea dirt will appear like black pepper flakes.
Like fleas, ticks seek blood to survive. That is why tick bites create inflammation at the point of entry that can worsen the longer the tick stays attached and releases its saliva into the skin. Additionally, secondary bacterial infection can occur add to the tick bite site that will lead to further irritation and itching.
Mites like mange (Sarcoptes, Demodex, etc.) are microscopic insects that burrow deep into the layers of the skin to feed and live. Chewing their way through your dog’s skin creates inflammation and leads to secondary infections (bacteria, yeast, etc.). Skin-lesions from mange can manifest all over the body, but the armpits, groin, ear margins, and areas having minimal hair (elbows, etc.) are most commonly affected.
4. Seasonal Allergies
Seasonal allergies, which mainly manifests with itchy skin in dogs, tend to be most prevalent during spring, summer, and fall, but regions that undergo frequently warm and/or humid weather can have a year-round allergy season. Blooming plants and flowers, grasses, weeds, and trees are common contributors to seasonal allergies.
5. Nutritional Allergies
While dogs most frequently suffer from allergies due to environmental triggers, allergic reactions to food is possible. Some dogs may be allergic to certain proteins (beef, dairy, chicken, etc.) and/or grains (wheat, corn, rice, etc.). This allergic reaction may exhibit in a number of ways, including skin inflammation and itching.