Many animals will contract allergies to environmental substances that can cause skin irritation. Allergens can include parasites (fleas and ticks); grass, tree and weed pollens; dust or mites. Of all the possible causes of primary itchiness and secondary skin infections in animals, fleas are far and away the most common cause. Just because you don't see fleas on the animal and any other animals in the household are not scratching doesn't mean you can rule them out as the cause. Fleas are EVERYWHERE and should never be taken lightly. If you dog is itching you must first make sure ALL animals in the household are on adequate flea control. There are several topical monthly flea control products available now that are extremely safe and effective. Ask you local veterinarian to recommend one and keep all your pets on them year round, regardless of where you live.
Allergies to pollen is also very common in animals. Dogs can sometimes show upper respiratory signs similar to hay fever in humans, but mostly it makes them itchy and can lead to a variety of secondary skin irritations and infections. The severity of such reactions can vary tremendously from dog to dog. Most dogs that are affected show seasonal signs when the offending pollen is prevalent. However, some clinical signs can become more severe and last longer as the dog ages. In addition, new allergies can develop at any time. The good news is that veterinarians are learning more about allergies every year and constantly developing new medications to combat the clinical signs. The bad news is that this is still a very inexact science, and much is still unknown about how the immune system reacts to environmental allergens. Skin testing is often used to diagnose the allergy, and injections to attempt to desensitize the animal are frequently employed, but the effectiveness of both treatments can be limited. On average, about 50% of animals show a good response to these treatments.
Dust and storage mites are another common source of skin irritation in dogs. These microscopic organisms are present in all homes and food storage areas. Dogs develop allergies to these over time and they can be affected, sometimes severely, on a year-round basis. It is impossible to completely eliminate these organisms from your home, but regular thorough cleaning and vacuuming can greatly reduce their numbers. In the case of storage mites, if you use a plastic container to store your pet's food, it should be cleaned and dried thoroughly between each refill. The longer the food remains in storage, the more the mites can multiply.
If you have an itchy pet and you have tried to eliminate the most common problem—fleas—your best bet is to visit you local veterinarian for more answers. If you investigate the causes and treat the secondary problems aggressively as soon as clinical signs begin you have the best chance of some degree of relief. Keep in mind, however, that allergic skin disease is a very complicated problem and diagnosis and treatment can be very frustrating, time consuming and expensive.