Allergies Allergies are common in dogs and cats. Allergies are common in dogs and cats. Symptoms may include: itching, sore ears, asthma, diarrhoea, skin infections and many others Allergies are common in dogs and cats. While the most common allergy seen in small animals is Flea bite dermatitis; food, plant, moulds, dust and pollen allergies can occur. Disease may show up as itching, sore ears, asthma, diarrhoea, skin infections and many other symptoms. Unless relieved these allergies can make your pets quality of life life pretty miserable. Appropriate treatment may involve removing the allergen (always best), desensitisation (60% success), medicinal shampoos, diet modifications, antihistamines or corticosteroids. Skin disease can prove very frustrating. Often the aim of treatment is to manage the condition ( allergic skin disease ).