Whole-body Disorders that Affect the Skin in Dogs

Several whole-body disorders produce changes in the skin. In some instances, the skin changes are characteristic of the particular disease. Often, however, the signs are not obviously associated with the underlying condition and must be carefully differentiated from primary skin disorders. Some of these secondary disorders are mentioned briefly below and are also described in the chapters on the specific disorders. Skin disorders can be associate

Tumors are abnormal growths of cells. Tumors affecting the skin or the tissue just under the skin are the most commonly seen tumors in dogs. Skin tumors are diagnosed more frequently than other tumors in animals in part because they are the most easily seen tumors and in part because the skin is constantly exposed to many tumor-causing factors in the environment. Chemicals, solar radiation, and viruses are just some of the things that can cause skin tumors. Hormonal

Ticks are blood-sucking parasites that attach themselves to animals and people. Once attached to a host, ticks feed voraciously. As they feed, ticks can transmit a large number of diseases, including Rocky Mountain spotted fever, ehrlichiosis, Q fever, and Lyme disease. Ticks also release toxins that can harm their hosts. Skin wounds caused by ticks can lead to secondary bacterial infections and screwworm infestations. Severe ti

In dogs, seborrhea is a skin disease that is characterized by a defect in keratinization or cornification of the outer layer of the skin, hair follicles, or claws. Keratinization is the process in which the protective outer layer of skin is being constantly renewed by new skin cells. Seborrhea results in increased scale formation, occasionally excessive greasiness of the skin and hair coat, and often secondary inflammation and infection.

Ringworm is an infection of skin, hair, or claws caused by a type of fungus. In dogs, about 70% of ringworm cases are caused by the fungus Microsporum canis, 20% by Microsporum gypseum, and 10% by Trichophyton mentagrophytes. In young or debilitated animals and in Yorkshire Terriers, infection may be persistent and widespread. The infecting fungus is spread easily in th

Pyoderma literally means “pus in the skin.” It can be caused by infection, inflammation, or cancer and is common in dogs. Most cases of pyoderma are caused by bacterial infections. Most of these are superficial and secondary to a variety of other conditions, such as allergies or parasites. Pyoderma that occurs in otherwise healthy animals usually resolves completely with appropriate antibiotics. Warm, moist areas on the skin, such as lip folds, f

Photosensitization is a clinical condition in which skin is oversensitive to sunlight; this condition is not sunburn. Certain molecules present in the skin are energized by light. When the molecules return to the less energized state, the released energy causes chemical reactions in the skin. Photosensitization can be difficult to distinguish from actual sunburn. Photosensitization is often classified according to the source of the photodynamic p

A parasite is any living thing that lives in, on, or with another living thing (known as a host) and that depends on the host for its food and shelter. While the parasite benefits from this relationship, the host does not and can be harmed in the process. Some parasites depend on a host for their entire life while other parasites depend on a host only during a part of their life. Many worms are parasites that infect dogs, cats, horses, and other animals. Some of thes

Nasal dermatoses are diseases of the skin on or near the nose. The nose itself is often referred to as the nasal planum. Some of these conditions are sometimes known as Collie nose or nasal solar dermatitis, depending on the cause. Many diseases may cause these conditions in dogs. These may affect the bridge of the nose (the muzzle), the nose itself, or both. In cases of pyoderma (

Mange is caused by microscopic mites that invade the skin of otherwise healthy animals. The mites cause irritation of the skin, resulting in itching, hair loss, and inflammation. Most types of mange are highly contagious. Both dogs and cats are very susceptible. Horses and other domestic animals can also be infected. There are several types of mange that affect dogs, including canine scabies (sarcoptic mange), ear mites (otodectic mange), walking dandruff (cheyletiel