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This article was published in 1981
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Enzootic Pneumonia in Pigs (E.P.)
K.J. Amstrong, Veterinarian, Elanco Products, West Ryde NSW
- Brief review of Pneumonia in Australia
- Description and outline of processes involved in E.P.
- Other respiratory diseases
- Practical approaches to treating E.P.
1. OVERVIEW OF PNEUMONIA IN AUSTRALIA
Three surveys have been undertaken looking at Pneumonia in slaughtered pigs in Australia. These indicated levels of infection ranging from 19.1% (Penny & Edwards, 1971, N.S.W.) to 68% in Victoria (Pullar, 1949). These surveys obviously could not consider the total number of pigs infected at one time or other during their life time. Many pigs will recover completely from Pneumonia and may not show macroscopic lesions at slaughter.
These surveys would help back up Switzer's observation 1970 that E.P. is probably the most common infectious disease of pigs worldwide.
When one considers that estimates of up to 20% reductions in F.C.E.'s have been made, (Goodwin, 1966) and of growth rate depressions of 25% (Betts & Beveridge, 1953) have been made, even low grade E.P. infections could be having substantial economic effects on our big industry. It is time that veterinarians, both private and with government bodies, began to play a far more influential role in the disease and management practices of our pig industry. After all, it is the veterinarians that have been extensively trained as the experts in disease control. Most of us know, however, that pig farmers are presently more influenced by other farmers, stock and station agents and drug company representatives, more than their local veterinarian.
The main emphasis of this discussion will be directed toward the diagnosis of E.P. and practical E.P. treatment and prevention programmes.
2. DESCRIPTION OF B.P.
- Causal agent M. suipneumonia.
- Mycoplasma are highly contagious.
- M. very closely associated with cell membrane.
- Are spread by close body contact.
- Carriers are important sources of re-infection e.g. sows and recovered pigs.
- High morbidity and low mortality (uncomplicated).
- Infection seen in young piglets in three weeks or older.
- Environmental conditions are of paramount importance with this disease.
Clinical Symptoms
- Coughing, dry unproductive cough particularly after feeding or exercise.
- More often seen in winter or change of seasons.
- Symptoms often not noticed until becoming complicated with bacteria such as P. multocida, C. pyogenes, Haemophilus sp., Streptococci and Staphlococcus.
- Illthrift.
Pathology
- Generally cardiac and apical lobes most affected.
- Right lung often more infected than the left lung.
Diagnosis
- From clinical symptoms and post-mortems.
- From isolation of Mycoplasma and 2o bacteria.
NOTE - Mycoplasma are exceptionally difficult organisms to culture and special transport media containing a bacteriostat should be used to send to diagnostic laboratories.
Complications of E.P.
- E.P. is often complicated by parasites, both Metastrongylus and Ascaris spp.
- This should be considered in an effective E.P. control programme
3. OTHER RESPIRATORY DISEASES
a. Porcine Pleuropneumonia
- H. parahaemolytica
- increasing incidents in Australia
- seen in pigs two to six months of age
- sudden onset .
Clinical Symptoms
- abdominal breathing, coughing and frothy discharge from the mouth and nose. Death within one to three days.
- it is highly contagious although immunity does develop in affected herds.
Pathology
- acute haemorrhagic fibrinous pleuropneumonia.
b. Glassers Disease
- H. suis
- M. hyorhinis
- seen in piglets three to twelve weeks of age
- sudden onset with fever as well as cough
- high mortality
- some arthritis develops in survivors
- most often seen after change in environmental conditions e.g. transport
- Pathology, Pleurisy, Pericarditis, Peritonitis
- treatment is difficult particularly if both Mycoplasma and Haemophilus are involved.
c. Atrophic Rhinitis
- H. bronchiseptica + I.B. Virus (?) + P. multocida
- does not occur in Australia.
4. PRACTICAL APPROACH TO TREATMENT AND CONTROL OF E.P.
a. Antibiotics
- no Antibiotic is 100% effective in treating Mycoplasma spp. because of their close associations with cell membranes
- injectable Antibiotics are more effective than water medications which are more effective than feed medications
b. Obviously correct diagnosis is essential - especially if 2o bacteria may be involved.
c) Sensitivity discs can be used as a guide to the choice of appropriate medications, however, differences between in vitro and in vivo responses should be kept in mind.
d. Useful medications include:
- Tetracyclines
- Tylosin
- Lincomycin
- Streptomycin
- Erythromycin
- Tiamulin
- Sulphadimidine
Generally speaking, treatment programmes are really only a fire brigade type exercise in so much as all that one can expect is to stop the disease getting worse. They also involve a great deal of labour.
Control Programmes
Long term control programmes are often more effective than to wait until clinical symptoms arise. These usually involve feed medications.
- Feed medications should be undertaken to prevent the spread of disease from the sows to the newly born piglets and from older carrier pigs.
- Simply, this could involve a two or three week feed medication for sows over five or six months and routine feed medication for weaner piglets.
- Feed medication programmes require considerable monitoring to ensure the correct levels of drug are in use and for the correct reasons. The selection of the most appropriate feed medication should be based on:
- the bacteria isolated
- spectrum of antibiotic
- development of resistance
- human medication implications
Successful feed medication programmes have been based on the use of several products which include: Tylan + Sulphur, Aureo-S-P, Linco-Spectin & Terramycin.