Glasser's Disease

Description

Glasser's disease is caused by the bacteria Haemophilus parasuis. It is a systemic condition affecting young pigs characterised by polyserositis, arthritis and meningitis. It is rapidly fatal in the acute form, in some cases animals die before the development of obvious lesions. In older pigs respiratory signs are most common such as bronchitis, other symdromes may also occur.

Signalment

The disease usually affects weanlings 6-10 weeks old when maternal antibodies wane but it can affect pigs of any age, particularly naive pigs introduced into a herd or through exposure to a strain to which there is little immunity. The stress of mixing, weaning and adverse environmental conditions are predisposing factors.

The disease occurs worldwide, it is endemic in most herds but incidence of clinical disease in the UK is sporadic due to widespread acquired resistance. Increased prevelance has been associated with PRRS, Circovirus and Swine Influenza. Mortality is high where there is no immunity, for example outbreaks in specific pathogen-free herds.

Diagnosis

Clinical signs

• Pyrexia
• Dyspneoa with abdominal effort
• Anorexia
• Cough
• Swollen joints and arthritis
• CNS signs, trembling and paddling
• Sudden death

Clinical signs develop rapidly, the disease is often fatal within 2-5 days. The skin becomes discoloured, turning red to blue before death. Expressed lesions vary between animals.

Survivors or those affected by the chronic form of the disease show less severe clinical signs of weight loss and depression, they become lame with arthritis, develop congestive heart failure, pericarditis or intestinal obstruction due to formation of adhesions. Pregnant sows may abort their fetuses.

Pathology

On post mortem examination there is obvious pericarditis, peritonitis and pleuritis The lesions may be fibrinous with adhesions and thrombi. In cases of fibrinous pericarditis there will also be signs of congestive heart failure such as pulmonary oedema, cardiomegally and hepatomegally.

The lungs show signs of suppurative bronchopneumonia and pleuritis.

There is also polyarthritis of the joints, they are inflammed with turbid yellow joint fluid and fibrin deposits in the joint cavity.

Treatment

Early treatment with parenteral antibiotics can be successful. Penicillin-streptomycin, ampicillin, oxytetracycline and potentiated sulphonamides are all effective.

Medicated water or feed for the duration of an outbreak will prevent the spread of the disease throughout the herd.

Prevention

An inactivated vaccine is available for protection against Glasser's disease, two doses should be given by IM injection 2-3 weeks apart before 10 weeks of age.

Other preventative measures include good management practice, minimising stress, avouiding mixing of age groups and the appropriate vaccination and isolation of naive stock being introduced to the herd.

Prognosis

The prognosis is poor. Treatment must be early if it is to be effective. In many cases the disease is too severe to treat and euthansia is recommended on welfare grounds.

References

• Jackson, G.G. and Cockcroft, P.D. (2007) Handbook of Pig Medicine Saunders Elsevier
• Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial
• Taylor, D.J. (2006) Pig Diseases (Eighth edition) St Edmunsdbury Press ltd