Diagnosis of causes of respiratory diseases in cattle.

Cattle with Pasteurella bronchopneumonia usually have a fever, abnormal respiratory sounds in the cranioventral lung fields, consolidation, pleuritis and abscesses. Lungworms primarily affect 4- to 6-month-old calves, which become febrile and dyspneic, with moist rales. Diagnosis is by fecal examination using the Baermann technic. Proliferative pneumonia usually affects stabled adults, which develop severe dyspnea and tachypnea. Diagnosis is by the history, clinical signs and lung biopsy. Acute bovine pulmonary emphysema is caused by ingestion of large amounts of L-tryptophan in lush pasture. Affected cattle have severe, acute dyspnea, an expiratory grunt and froth around the muzzle. Diagnosis is by the history and clinical signs. Bronchiolitis obliterans narrows the airways of older animals to cause dyspnea. A positive response to corticosteroids aids diagnosis. Anaphylaxis occurs in cattle of all types and ages and is precipitated by various antigens in a type-I hypersensitivity reaction. Use of atropine aids diagnosis. Allergic or hypersensitivity pneumonia is caused by an allergy to insecticides, dead ascarid larvae or the mold, Micropolyspora faeni. Diagnosis is by a history of insect fogger use, finding M faeni in the forage, and typical histologic lesions in lung samples. Cattle with caudal vena caval thrombosis have dyspnea, a fever, froth around the muzzle, an expiratory groan and hypergammaglobulinemia. Malignant catarrhal fever is diagnosed by a history of previous exposure to sheep and finding swollen lymph nodes, fever, neutropenia and arteritis.