Severe Outbreak of Glasser's Disease in VLA Report

by 5m Editor
1 July 2009, at 9:12am

UK - The Monthly Scanning Surveillance Report for May 2009 from the Veterinary Laboratories Agency (VLA) highlights a case of swine dysentery of unknown origin, parasitic pneumonia, and a severe outbreak of Glasser's disease.

Alimentary Tract Diseases

Iron deficiency anaemia

The carcasses of two, three-week-old piglets were submitted to Starcross investigate an outbreak of diarrhoea. Gross lesions included subcutaneous oedema, fibrin in the abdomen, hydrothorax, pulmonary oedema, generalised carcass pallor and focal pallor of the liver consistent with hepatic necrosis. The findings were suggestive of iron deficiency anaemia, which was subsequently confirmed by liver biochemistry. Rotavirus antigen was also identified as a potential cause of the diarrhoea.

Swine dysentery

Faecal samples were submitted to Thirsk from a 1,000-sow breeding unit where a pen of 70 gilts developed an outbreak of scouring containing blood and mucus. About 80 per cent of the gilts, which weighed about 80 kg, were affected. Brachyspira hyodysenteriae was confirmed from cultures and from PCR testing. MIC testing revealed the isolates to be fully susceptible to lincomycin, tiamulin and valnemulin. The unit had a high level of biosecurity and the only pigs that do come onto the site were AI stud boars that were kept separately from the sows and the gilts. The source of the outbreak is therefore unknown. The unit had no previous history of swine dysentery.

Respiratory Diseases

Parasitic pneumonia

Bury investigated an outbreak of respiratory disease occurring from eight weeks of age in approximately 25 per cent of 8,000 outdoor-reared finishers. Previous submissions had revealed active early PRRSV infection post weaning. One older finisher pig underwent necropsy and had grey-pink consolidation of the lungs. Histological findings were of a sub-acute to chronic exudative eosinophilic bronchointerstitial pneumonia with numerous nematode profiles indicating parasitic pneumonia, probably caused by Metastrongylus apri.

Actinobacillus pleuropneumoniae

Sudden deaths were reported in a large indoor farrow to finish unit affecting eight- to nine-week-old pigs. These were on a wet bed of fully slatted floors in environmentally controlled housing. Four dead pigs were examined at Langford ranging in weight from 15.5 to 29 kg. The main findings in all pigs were a number of dark raised consolidated areas mainly in the dorsal part of the lungs with a covering of fibrinous pleurisy. Actinobacillus pleuropneumoniae was isolated from all the lungs and was further identified as serotype 3. In the UK, APP serotypes 3, 6 and 8 predominate.

Glasser's disease

Four live weaner pigs approximately five weeks old were submitted to Thirsk for post-mortem examination as part of an investigation into a particularly severe outbreak of Glasser's disease on a 750-sow pyramid that practised two-site production. A weekly farrowing system was in place and approximately 300 pigs weaned per week into flat decks. Recently, the proportion of gilts in the breeding herd had increased as part of attempts to try and increase the number of piglets born alive. This increase in gilts had coincided with a worsening of disease in the first stage flat decks.

The disease consisted of pigs becoming tucked-up, breathing badly with pallor and rapid condition loss within ten days of weaning. Mortality among affected pigs was high and prompt treatment with antibiotics was successful in only a proportion of affected animals. Gross findings on post-mortem examination revealed polyserositis in all four pigs with additionally lung consolidation in two of the four pigs. Culture of the affected areas revealed growths of Haemophilus parasuis serotype 10, the most frequently isolated serotype of H. parasuis from the UK archive in a survey published in 2006 (Morris, 2006).
Reference: Morris, S.J. et al., 2006. Characterisation of Field Isolates of Haemophilus parasuis from the UK. Proceedings of the 19th IPVS Congress, Copenhagen, Denmark 2006. Volume 1, abstract number 0.38-01))

Other diseases


Six of 700 16- to 20-week-old finishers died after short-term recumbency on a 200-sow indoor breeder finisher unit. An affected pig was submitted to Bury, the only one affected in a pen of 30. Rearing pigs were vaccinated for Mycoplasma hyopneumoniae and sows were vaccinated for PCV-2. The pig exhibited depression and shivering with a rectal temperature of 104°F. The pig was in good body condition, with slightly enlarged and oedematous lymph nodes and pale kidneys that were, firm to cut, swollen and with dark red pinpoint foci over the renal cortices. Urea concentration in the aqueous humour was high (60.8mmol/l, reference range in serum 2.6 to 8.3 mmol/l). These findings pointed to likely PDNS and histopathology confirmed the diagnosis. There was no evidence of PRRSV involvement.

Osteochondrosis dissecans

A nine-month-old breeding boar was submitted to Bury with a history of being 'twitchy' for approximately two months and unwilling to walk; neck pain had been suspected. Post-mortem examination revealed severe osteochondrosis dissecans in both elbow joints and milder similar pathology in the right stifle joint with secondary joint changes due to arthritis. In view of the history of twitching, histopathology was performed on the brain, which was unremarkable. The clinical signs were likely to have been due to pain from the osteochondrosis dissecans and the presence of lesions in both elbow joints may have masked obvious lameness.

Further Reading

- You can view the full report by clicking here.

Further Reading

- Find out more information on the diseases mentioned in this article by clicking here.

5m Editor