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
Lice are small, flightless insects that live in the hair or feathers of animals and people. There are 2 basic types of lice. Biting or chewing lice (order Mallophaga) infest both birds and mammals. They feed mostly on skin debris and the secretions of their hosts. Blood-sucking lice (order Anoplura) are skin parasites of mammals only. Typically, lice are species specific; that is, they do not readily transfer from one animal species to another.
Pruritus is defined as an unpleasant sensation within the skin that provokes the desire to scratch. Itching is a sign, not a diagnosis or specific disease. The most common causes of itching are parasites, infections, and allergies. There are many skin diseases that do not initially cause itching. Itching may develop because of secondary bacterial or yeast infections. It is possible that by the time itching develops the initial cause is long gone.
Hyperpigmentation is a darkening and thickening of the skin seen in dogs. It is not a specific disease but a reaction of a dog’s body to certain conditions.
Hyperpigmentation appears as light-brown-to-black, velvety, rough areas of thickened, often hairless skin. The usual sites are in the legs and groin area. It can be primary or secondary. Primary diseases that cause hyperpigmentation can occur in any breed but especially Dachshunds. Signs are
A hygroma is a fluid-filled sac that develops over bony prominences and pressure points, especially in large breeds of dogs. Repeated trauma from lying on hard surfaces leads to inflammation. This results in a dense-walled, fluid-filled cavity. A soft, flexible, fluid-filled, painless swelling develops over pressure points, especially the elbow. If long lasting, severe inflammation may develop, with ulcers, infection, abscesses, granulomas (masses of inf