Ovine pulmonary cytomegalovirus

Viral Pulmonary Disorders in Animals: Neoplastic and Nonneoplastic

Respiratory infections in animal species are as ubiquitous as they are in humans. Species that may be affected include mammals, birds, and reptiles. In these animal species some viruses primarily infect the respiratory tract, while other viruses infect non-respiratory organs. Viruses are generally classified according to the type of their nucleic acid, their protein structure, and whether or not they have a lipid-containing envelope surrounding the viral particle. In general, most viruses gain entry into the lungs via the conducting airways. In nonprimate mammalians these infections are most prominent in the cranioventral lung lobes because of their horizontal position. Table 24.1 lists some of the major viruses that cause pneumonia and other lung diseases in animals.

Pulmonary lesions in lambs experimentally infected with ovine adenovirus 5 strain RTS-42

Twelve lambs were inoculated transtracheally and intranasally with Mastadenovirus ovi 5 strain RTS-42 and killed sequentially. Pulmonary lesions were studied by light and electron microscopy. Four lambs served as sham inoculated controls. Pulmonary lesions consisted of multifocal areas of bronchiolitis and alveolitis associated with necrosis and sloughing of isolated type I and type II alveolar epithelial cells and nonciliated bronchiolar epithelial cells. This was followed rapidly by hyperplasia of the remaining epithelium and repair of the damage. A cellular infiltrate of neutrophils and macrophages began at 2 days after inoculation, peaked at 4 days after inoculation, gradually diminished until minimal at 12 days after inoculation, and was resolved at 21 days after inoculation. Surfactant was abundant and, along with debris, was removed from the alveoli by macrophages. Clinical disease was not seen, but lesions were believed to be sufficient to allow bacteria to colonize the lungs and cause severe disease.