Does your dog keep you awake at night scratching? Persistently itchy pets aren’t happy pets Itching is most commonly the result of suffering from one or more allergies. *flea allergy occurs in 60-70 % of itchy dogs. Just one bite needed to cause intense irritation in a dog with a flea hypersensitivity (a substance in the flea’s saliva is the trigger). * Atopic dermatitis is the second most common cause of itching. A genetic defect