I forgot to mention allergies DUE TO FOOD OR AIRBORNE USSUALLY, not always start with itchiness &/or redness of feet, ears & eyes. If the animal is allergic to a cerytain bug (flea etc) or object (leaves, bedding, product like shampoo or etc) then it may be only noticable in one area but ussually an allergy will cause multiple symptoms.
If you suspect an allergy I reccomend an allergy test, not too expensive & it saves a lot of time, money & trouble in the long run!