(279) Pneumonia is normally uncommon in the mature herd but occasionally occurs in the gilt if immunity levels are low. However if influenza or PRRS viruses enters the herd for the first time or herd immunity wanes, periodic outbreaks involving a small number of sows may occur. When a new respiratory pathogen is introduced into the herd for the first time, for example, a virulent strain of Actinobacillus pleuropneumoniae, severe pneumonia is likely to develop in all ages of animals.

Clinical signs

These are seen at a herd level when new infections first enter. There is wide spread coughing and up to 20% or more severely ill animals. The respiratory rate is elevated with some sows showing acute respiratory distress.

In herd breakdowns with enzootic pneumonia or actinobacillus pleuropneumonia mortality can be as high as 10 to 15% if prompt treatment is not undertaken. If a clinical picture of widespread, sudden and progressive respiratory disease develops, then suspect a herd breakdown with one of the above organisms.

Diagnosis

This is based on the clinical signs of coughing, rapid breathing a high temperature and post-mortem examinations. At an individual level sows may develop pneumonia due to infectious agents already in the herd. The introduction of swine influenza into a herd is usually dramatic, with large numbers of sows off their food over a period of 3 to 7 days. Wide spread coughing and depression may be seen. In the case of a breakdown with enzootic pneumonia (in a herd that was previously free) the onset may be insidious with some inappetence but a gradual spreading cough over a period of 2 to 3 weeks. It may also appear to develop rapidly affecting sows more severely. There is likely to be severe pneumonia and some mortality if the disease is not controlled. Laboratory tests involving serology and microbiology are necessary to identify the possible causes.

Treatment.

• Usually pneumonia in the sow involves a mixed infection of viruses and secondary bacteria. Broad spectrum antibiotics such as OTC, penicillin streptomycin or amoxycillin are indicated.
• Inject individual cases daily for 3 to 4 days.
• For influenza with secondary bacteria:
  - Combine CTC or OTC in the water at the onset together with in-feed medication at a level of 600g/tonne. - Antibiotic cover is required for at least 14 to 21 days.
• Enzootic pneumonia - If there is a herd breakdown, medicines specifically effective against mycoplasma are indicated
  - Lincomycin - In feed, water, or by injection. - Spectinomycin - Injection.
  - Tiamulin - In feed, water, or by injection.
  - Tylosin - In feed, water, or by injection.
  - Chlortetracycline - In feed, or water.
  - Oxytetracycline - In feed, water, or by injection.
• It is important in the early stages of a breakdown to control the levels of infection, particularly in the numbers of organisms excreted into the air, until an immunity has developed. This can be achieved by using 600-800g/tonne of OTC or CTC in feed for two weeks reducing this to 200 to 300g over the next 3 to 4 weeks.
• Actinobacillus pleuropneumonia. If there is a herd breakdown early treatment of individuals is necessary together with preventative medication in-feed or water. Individuals should be injected with either OTC, penicillin/streptomycin, ceftiofur or sulphonamides.