App (Actinobacillus pleuropneumoniae, pleuropneumonia)

Description

The Actinobacillus pleuropneumoniae (App) bacteria, has at least fifteen different serotypes, some of which do not produce any clinical signs, while others may cause serious disease. The serotypes vary depending on the country. Serotypes 1,2,5,9 and 11 are normally quite virulent, while serotypes 3 and 7 are quite mild. The App is transported in the tonsils and the upper respiratory tract. It is transmitted in short distances through aerosol and only survives outside the pig for a few days.

The organism may affect the pig from weaning to slaughter, but normally it affects pigs 8 to 16 weeks old. The incubation period is very short; as short as 3 hours. The toxins produced by the bacteria can cause severe pulmonary damage. Infected animals can carry the organism during several months without showing any symptom.

App is not very common in sows, unless they did not had previous contact, or unless the subclinical disease is triggered by PRRS or influenza.

Symptoms

All ages

Not very common in adult pigs and very young piglets, except when the farm did not have previous contact with App.
Sudden death/low or high mortality – the unique symptom is a nasal bloody discharge.
Sudden death - no symptoms, more than 1% of the deaths are in this category. Post mortem examination is necessary.
Breathing difficulties.
Ears turn blue.
Severely depressed animals .
High body temperature.
Loss of appetite.
Pleuritis.
Nasal bleeding.
Lameness.
Pale pigs.
Pneumonia.
Bad general condition – deteriorated and poor looking.

Causes / contributing factors

Introducing infected or carrier pigs
Can be transmitted through fomites and visitors.
Sudden temperature changes.
Stress/movements.
Nutritional changes
Continuous flow production.
High animal density.
Other pulmonary diseases (PRRS, influenza).

Diagnosis

Based on the farm history, clinical signs, post mortem examination including slaughterhouse exams and culture of the organism. Pulmonary lesions are very typical. Serology may be used to identify serotypes, but its interpretation can be difficult due to cross reactivity between serotypes.

App must be differentiated from enzootic pneumonia, PRRS, influenza, and pneumonia caused by Salmonella choleraesuis.

Control / prevention

Due to the acute course of the disease, it is important to identify the clinical cases quickly and inject the affected animals. The infected pigs stop eating and/or drinking, so medicating trough feed or water is not an adequate treatment method. App is sensitive to a wide range of antibiotics. The following antibiotics are effective.

Ampicilin.
Ceftiofur. This product acts quickly and provides a good response
Enrofloxacin.
Florfenicol.
Long action chlortetracycline can be used in chronic cases. Repeat every two days.
Penicilin/streptomycin.
Tiamulin.
Tildipirosin.
Tilmicosin.
Tulathromycin.

It is important to determine the time the outbreak can take place and administer strategic medication before it appears.

Medication used in feed during the risk period include:

Chlortetracyclin.
Fenoximetil penicilin.
Trimethoprim/sulfa.

Preventive medication in feed is not always effective, probably due to the speed of the disease’s onset, and the quick loss of appetite.

Water medication during the risk period may result more effective to control the disease. Animals should be treated during 4 to 7 days. Use the same antibiotics used in feed.

In acute outbreaks, the population at risk should be examined three times a day in order to identify the disease as soon as possible. It might be necessary to inject or medicate the water of all the group. The decision to inject depends on the balance between the result obtained when injecting, and the risk of increasing the number of pigs presenting the disease due to the stress caused by the associated handling.

There are several vaccines available. These vaccines should include the specific strain of the outbreak.

Select replacement animals from herds negative to App.