In the majority of herds in which the bacterium is endemic, sows produce a strong maternal immunity which normally persists in their offspring until 8 to 12 weeks of age and as a result, the effects of the infection in weaners are usually nil or very minimal. The pigs become sub-clinically infected when still protected and then stimulate their own immune response. If however the maternal immunity wears off before they become infected they may develop severe disease. It can however become a secondary organism where there are other major pathogens and in particular enzootic pneumonia. Outbreaks of disease are sometimes experienced in sucking pigs, particularly in gilt herds.

Clinical signs

Acute disease
Pigs with glässers disease become rapidly depressed, with an elevated temperature, stop eating and are reluctant to rise. Hps attacks the smooth surfaces of the joints, coverings of the intestine, lungs, heart and brain. In young growing pigs meningitis or middle ear infections are common together with pneumonia, heart sac infection, peritonitis and pleurisy.

Hps also causes individual cases of arthritis and lameness with acute pain, fever and inappetence. It is respiratory spread and a characteristic feature is a short cough of only 2-3 episodes. Sudden death in good sucking piglets is not uncommon in herds with a problem and in particular when immunity in gilt litters is low.

Chronic disease
Sucking piglets are often pale and poor growing and 10-15% may be affected in a litter. Such pigs then continue into the growing period with poor growth. When long standing pericarditis is a feature sudden deaths occur.

Diagnosis

This is confirmed by clinical observations, post-mortem examinations and isolation of the organism in the laboratory but it is not an easy one to grow.

Similar diseases

These would include:

• Actinobacillus suis.
• App.
• Mulberry heart disease.
• Streptococcal meningitis.
• Streptococcal septicaemias.