HERD HEALTH
PIH-29
pork industry handbook
COOPERATIVE EXTENSION SERVICE • PURDUE UNIVERSITY • WEST LAFAYETTE, INDIANA
Mycoplasmal Pneumonia and Other Mycoplasmal Diseases of Swine
Authors
Alex Hogg, University of Nebraska
William P. Switzer, Iowa State University
Daniel O. Farrington, Iowa State University
Reviewers
Don McKenzie, Marcellus, Michigan
Lewis J. Runnels, Purdue University
William E. Wise, University of Kentucky
Swine producers are often confused by the complexity of the mycoplasmal infections. This fact sheet is an attempt to clarify the information that is currently available about these swine diseases. There are three recognized Mycoplasma spp. of bacteria that cause disease in pigs— Mycoplasma hyopneumoniae, Mycoplasma hyorhlnis and Mycoplasma hyosynovlae.
Mycoplasmal Pneumonia
Mycoplasmal pneumonia (in the U S.) or porcine enzootic pneumonia (England, and other countries) is caused by Mycoplasma hyopneumoniae. Another synonym for this disease is swine enzootic pneumonia (SEP). Fifteen years ago this disease was called virus pneumonia of pigs (VPP); since that time it has been discovered that a mycoplasma, not a virus, is the cause. Mycoplasma are very small and readily pass through ordinary bacterial filters. In addition, mycoplasma are difficult to grow in the laboratory. For these reasons, it was originally assumed that mycoplasmal pneumonia was a virus.
Mycoplasmal pneumonia affects pigs of all ages, starting with those as young as 7-10 days of age. It is estimated that 90% or more of the swine herds in the midwestern United States are infected with mycoplasmal pneumonia.
Mycoplasmal pneumonia is a chronic disease. A high percentage of the pigs are affected, but the death loss is
low. Pigs usually show first signs of the disease between 3 and 10 weeks of age. The incubation period is 10 days or more after exposure to carrier swine. The pigs have a dry, nonproductive cough that is most noticeable after exercise. Pigs may cough for only 1-3 weeks, or the coughing may persist indefinitely. Other conditions such as influenza, pasteurella pneumonia and lungworms also cause pigs to cough and should be considered in making a differential diagnosis.

In general, pigs with mycoplasmal pneumonia continue to eat reasonably well, but some do not grow at a normal rate if lesions are extensive or secondary bacterial pneumonias occur. Severe pneumonia also results when mycoplasmal pneumonia is complicated by large numbers of ascarid (roundworm) larvae passing through the lungs. Pigs are also more severely affected when lungworms are present. Growth retardation due to mycoplasmal pneumonia is variable. Generally, the more severe the lesions the greater the effect.

Adequate treatment of established mycoplasmal pneumonia is not currently available. Several promising treatments are being investigated. Sulfas and antibiotics are very useful in the control of secondary bacterial pneumonias. Good nutrition, a warm, dry, dust- and draft-free environment and ascarid and lungworm control programs are useful in minimizing the effects of mycoplasmal pneumonia. Uncomplicated lesions may heal in 55-60 days without treatment.
Cooperative Extension Work in Agriculture and Home Economics. State of Indiana. Purdue University and U. S. Department of Agriculture Cooperating. H. G. Diesslin, Director, West Lafayette, Ind. Issued in furtherance of the Acts of May 8 and June 30, 1914. It is the policy of the Cooperative Extension Service of Purdue University that all persons shall have equal opportunity and access to its programs and facilities without regard to race, religion, color, sex or national origin.