Background and history

Pneumonia is normally uncommon in mature acclimatised animals (unless exposed to a new organism), it occasionally it occurs in gilts but is very common in the growing animal. 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. Mortality in naive animals can be as high as 10 to 15% (no immunity) if prompt treatment is not undertaken.

The onset of swine influenza is usually sudden and affects most pigs. The onset of enzootic pneumonia in a naive herd may be insidious although it may later develop rapidly affecting many sows severely. There is likely to be severe pneumonia and some mortality if the disease is not controlled in herds infected for the first time.

Of all the diseases that affect growing and finishing pigs, chronic respiratory disease is the most economically important. It is extremely common and can be difficult to prevent and control. Growth rates and feed-intake are depressed together with poor feed efficiency and in some herds there is heavy mortality. The control of respiratory disease requires an understanding of the complexities and interaction between the organisms that are present, the pig and the management of the environment.

Pneumonia is affected by:

• The presence of respiratory pathogenic organisms.
• The virulence of the pathogens present.
• The level of the pathogens in the house environment.
• The immunity of the pig and the time of exposure to the organisms
• The presence of secondary opportunistic bacteria.
• The interactions between management, environment, the diseases and the pig

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.

Weaners and growers

• Coughing.
• Rapid breathing.
• Dehydration.
• Inappetence.
• Discharges from the eyes - conjunctivitis.
• Poor circulation.
• Blue discoloration of the skin.
• Loss of condition.
• Huddling.
• Fever.

Sows

• Widespread coughing.
• Some sows obviously very ill.
• Respiratory rate is elevated, some showing acute respiratory distress.

Piglets

• Coughing.
• Heavy breathing.
• Loss of condition.
• Dehydration.

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.

Causes

• If pathogens such as influenza, PRRS virus, Mycoplasma hyopneumoniae or a virulent strain of Actinobacillus pleuropneumoniae enter a susceptible herd for the first time dramatic outbreaks may occur in sows.
• Poor environments.
• Incorrect ventilation and humidity.
• High stocking densities.
• Diseases are commonly transmitted through the movement of carrier pigs.
• Incoming pigs.

Increased clinical disease is associated with the following;

• Overcrowding and large group sizes.
• Less than 3 cu.m. air space/pig and 0.7 sq.m. floor space/ pig.
• Houses that are too wide for good air flow control.
• Variable temperatures and poor insulation.
• Variable wind speeds and chilling.
• Low temperature, low humidity environments.
• High levels of carbon dioxide and ammonia.
• High dust and bacteria levels in the air.
• Pig movement, stress and mixing.
• Housing with a continuous throughput of pigs.
• A combination of diseases, particularly PRRS, App, flu, and aujeszky's.
• Poor nutrition and dietary changes at susceptible times.

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.