Porcine Respiratory Disease Complex/Mycoplasmal Pneumonia
Overview
Mycoplasmal pneumonia in swine (MPS) is a chronic pneumonia characterized
by a dry, hacking cough; retarded growth; decreased feed efficiency; low mortality and high
morbidity. As one of the most common diseases in the swine industry, it is present in 80 percent
of U.S herds and is at least that prevalent around the globe. Research at the University of Kentucky
in the United States has shown that even mild symptoms disguise inefficiency that costs up to $7.00 (U.S.)
or more for every hog.(1)
Causes
Mycoplasmal pneumonia is caused by Mycoplasma hyopneumoniae, organisms
that have been recognized for almost a century. An important triggering mechanism for the disease is
stress, which may result from:
- movement from pen to pen
- change in nutrition from pen to pen or building to building
- environmental factors such as dust, ammonia, temperature and humidity
- crowding
- commingling
- parasites
(1) University of Kentucky, Morganfield, Swine Research Report, 1985.
Clinical Signs and Diagnosis
The first sign of mycoplasmal pneumonia is a dry, nonproductive cough. In
3-site production systems, it commonly occurs 3-10 weeks after pigs move to finisher. The
cough may last 1 to 3 weeks or continue indefinitely. Pigs with mild infections usually don't
look sick. Pigs with more severe infections, however, become stunted and develop rough coats
of hair. These pigs are the ones most likely to be your "tail-enders."
A definitive diagnosis should involve a combination of tests that detect the organisms by
culture, antigens by fluorescent antibody examination (FA) or immunohistochemistry (IHC),
nucleic acids by polymerase chain reaction (PCR), or serum antibodies by serology. These
tests should be performed along with clinical evaluation of the pigs and demonstration of
typical gross and microscopic lesions on necropsy. Identifying other disease and production
factors that promote mycoplasmal pneumonia is also important.(1)
(1) Pat Halbur, "Making the Diagnosis with Serology, Antigen Detection and
PCR," in Mycoplasmal Pneumonia in Modern Swine Production Units, Proceedings of the
Iowa State University Veterinary Medicine Seminar, April 22, 1997, p.3.
Management
Adverse environmental conditions coupled with management problems can
markedly affect the severity of MPS. The following steps can help in its control:
- Reduce stress caused by frequent moves, overcrowding and extremes of temperature.
- Maintain a clean environment with good ventilation and temperature control.
- Disinfect pens before moving pigs into them.
- Provide proper nutrition and keep animals free of worms.
- Choose the proper medication, one that penetrates lung tissues and is effective against Mycoplasma.
Treatment
See LINCOMIX®
lincomycin hydrochloride for more information on treatment options.
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