The dog's skin is a dynamic and vital organ. No matter if your dog is shortor longhaired, her skin is always shedding dead cells and replacing them with new ones. The skin is made of two layers: the epidermis, or outer layer of skin cells, and the dermis, or second layer. A dog's skin is prone to many problems that can affect either or both layers of skin — most notably, itching, hair loss, swelling and inflammation, and flaking. Because skin problems are often the most visible and pronounced of ailments afflicting dogs, it's not surprising that they represent a large percentage of the overall cases referred to veterinarians.

Scratching and Itching

While all animals occasionally scratch themselves (including we humans!), excessive or constant scratching or itching is the sign of a problem. The most common causes are fleas, hypersensitivity (an immunologic or allergic reaction), and pyoderma (a bacterial infection). If the underlying cause isn't determined, the condition can grow increasingly worse.

At the first signs of itching, check your dog for fleas. You can do this by moving the fur backwards and looking for fleas themselves or for “flea dirt” — the digested blood fleas excrete that indicates their presence. If your dog has fleas, you will need to remove them from her body and from the environment.

Some dogs are so sensitive to flea bites that they develop flea allergy dermatitis. The dog develops an immunologic hypersensitive reaction to the saliva injected by the flea when it feeds on the dog. By constantly licking, scratching, and chewing at her skin, the dog develops areas of hair loss, which can further progress to open sores that lead to infection. The area most affected seems to be the base of the tail and lower back.

Flea allergy dermatitis typically develops when a dog is three to five years old, and it can be extremely tough to reverse, even if your dog is fleafree! The sooner your veterinarian can diagnose the condition, the sooner you can begin treatment and hope to alleviate the symptoms. Treatment will involve being vigilant about keeping your dog and home flea-free, the use of special shampoos, dips, or ointments to prevent itching, and possibly a prescription for anti-inflammatory drugs.

Your dog's itching may be caused by an infestation of mange, another external parasite that aggravates the skin. If there is no sign of fleas on your dog or in your home, you can suspect mange. A skin scraping and examination by your veterinarian will confirm the condition if it exists, and you can begin treatment.

Allergies

Dogs can also develop immunologic hypersensitivities to foods — anything from beef to wheat to dairy. This is why so many premium diets feature ingredients such as lamb, rice, or turkey — protein sources to which dogs are less sensitive.

A hypersensitivity reaction to things in the environment, such as certain fabrics, detergents, molds, or fungi, usually means the dog is allergic to that thing. Symptoms usually develop when the dog is one to three years old and begin to show in the spring or fall. Areas of the body most affected include the face, stomach, paws, and, oddly enough, the creases of the elbows. If your dog is constantly rubbing his face, licking and scratching his paws, or itching his tummy or elbows, you should suspect an allergic hypersensitivity. Left untreated, the itching will lead to areas of broken, exposed skin that are ripe for infections. Often, paw licking will develop into a behavioral habit, perpetuating the condition.

Because of the enormous number of potential allergens in the dog's environment, your veterinarian will need to evaluate your dog's symptoms carefully and perform blood and skin tests to try to determine the allergen. Once this is pinpointed, elimination of the source is necessary, and you will probably need to use special shampoos and ointments to alleviate itching.

Infections

Bacterial infection is the result of skin that's under attack and losing the battle. The skin of a healthy dog has certain bacteria that live on its surface and within each hair's follicle. This “good” bacteria wards off infection by “bad” bacteria. But when something happens to disrupt the balance, harmful bacteria invade and proliferate, causing serious infection and some severe and very painful problems.

Hot Spots

These are quarter-sized areas of red, moist, swollen sores, typically found on longhaired dogs during warm, humid weather. They can be caused by the dog's licking itself in response to some other problem such as a parasitic infection or general hypersensitivity. Often the cause goes undiscovered. Treatment involves applying antibiotic ointment to the wound and using an Elizabethan collar on the dog so she cannot reach the spot to continue licking or chewing at it.

Skin-Fold Pyoderma

Dogs with areas of thick, folded skin on their bodies, such as Chinese Shar-Pei, Bloodhounds, Mastiffs, Pugs, and others, can develop infections in between the folds. That's because the fold creates a warm, moist spot — prime breeding grounds for bacteria. Regular inspection of the folds can help prevent infection, and antibiotic ointment can help treat it.

Another spot bacteria may breed rapidly is between the toes, and this is only exacerbated by the dog's licking. Scratches or cuts to the skin between the toes often go unnoticed, which can also lead to infection. Again, good grooming habits can go a long way toward preventing this condition.

Seborrhea

When there is an imbalance of new cell growth to replace dying cells, the result is a thickening of the skin with noticeable shedding of the dead cells. This is called seborrhea. Symptoms include extreme flakiness, an overall greasiness to the skin and coat, an unpleasant and persistent odor to the coat, itchiness, and bald patches of thick skin. The causes of seborrhea include hormonal imbalance, parasitic infection, excessive bathing or grooming, and nutritional disorders — all factors that contribute to the skin's not being able to properly regulate itself. Diagnosis is fairly simple, but treatment can be quite involved and may necessitate antibiotics, special shampoos, and anti-inflammatories.