Actinomyces bacteria normally live in the mouth and in the nasal passages near the throat. Several species are associated with diseases in dogs.
Actinomyces bovis has been identified infrequently in infections in dogs and other mammals. Disease occurs when this bacterium is introduced to underlying soft tissue through penetrating wounds of the mouth (such as those that occur from carrying sharp objects in the mouth or r
Actinobacillosis is caused by bacteria in the genus Actinobacillus. Several different forms of disease occur, depending on the particular species of Actinobacillus involved and the type of animal infected. Soft tissue infections are common, and lymph node involvement is frequently a step in the spread of the disease throughout the animal’s entire body. Bony tissue close to infected muscles or other tissue may also
A variety of structural and functional defects have been described in animals. These birth defects are usually classified by the body system primarily affected, and many are discussed in this book under the appropriate body system section. Defective newborns have survived a disruptive event during embryonic or fetal development. Defective development may also cause embryonic loss, fetal death, mummification, abortion, stillbirth, a newborn not capable of living, or birth defects.
There are many disorders that can affect multiple parts of the body. These may be caused by bacteria, viruses, poisonous or toxic substances in the environment, and other health hazards. Disorders affecting multiple body systems can also be inherited or develop while the animal is still in the womb. Diseases or conditions that involve multiple organ systems may also be described as systemic or generalized.
Many disorders are discussed in this chapter. A listi
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