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UK Pig Disease Surveillance Report (July 2008)

by 5m Editor
11 September 2008, at 12:00am

The latest UK Veterinary Laboratories Agency (VLA) Surveillance Report for Pigs. Highlights include three reports of swine influenza due to different virus strains, indicating a changing seasonality for this pathogen; swine dysentery; rotavirus; meningitis and bracken poisoning.

Enteric Diseases

Swine dysentery (B. hyodysenteriae)

Swine dysentery was confirmed by culture and PCR as the cause of diarrhoea and wasting in an unspecified number of finisher pigs over a three-week period, with scour containing mucus and blood.

Rotavirus

Diarrhoea was reported in three- to five-week old piglets on a 620-sow unit. There had been a poor response to Aureomycin therapy. Two piglets were submitted to investigate the problem. Both were in poor condition and there was gross evidence of an enteritis. The intestinal contents of one were particularly yellow. Rotavirus was detected by ELISA confirming rotaviral enteritis. No other enteropathogens were identified.

A problem of scour in four-day-old piglets prompted the submission of three live piglets for investigation. All had received antibiotics at birth and a coccidiosis treatment at four days of age. The scour appeared to start between three to six days of age and was unresponsive to Clamoxyl. Post-mortem examination of all three pigs revealed congested mucosa of the small intestine, oedema of the spiral colon and a watery scour with yellow floccules. Rotavirus was detected by PAGE in faeces from all three pigs confirming a virological aetiology to the problem.

Respiratory Diseases

Swine Influenza

A gilt and three piglets were examined following an outbreak of respiratory disease in a 700 sow-breeding unit. Pneumonia was observed grossly and confirmed histologically in the gilt and two of the piglets. Immunohistochemistry and virus isolation revealed infection with Influenza virus H1N2 in all three, with A. pyogenes also isolated from the gilt’s lung.

On another outdoor farm, respiratory disease was characterised mainly by coughing with high (100 per cent) morbidity and low mortality. Gross examination of four weaners/growers identified diffuse pulmonary consolidation with enlargement of associated lymph nodes and white focal lesions of the liver (milk spot lesions characteristic of migrating ascarids). A dual respiratory problem of swine influenza and enzootic pneumonia was suspected on histopathology with ulcerative lesions in the airways and lymphoplasmacytic coughing. The diagnosis was confirmed by immunohistochemical demonstration of swine influenza viral antigen, and avian-like H1 influenza virus similar to A/SW/195852/92 was isolated. Mycoplasma hyopneumoniae was demonstrated by DGGE.

An investigation was undertaken into a respiratory disease outbreak on a finisher unit, and this resulted in the isolation of Streptococcus suis type 7 from lung tissue along with Haemophilus parasuis. In addition, an H1N1 influenza virus was also isolated.

Disease of the Nervous System

Meningitis due to Streptococcus suis

Sporadic deaths in weaned pigs prompted an on-farm post mortem examination by the PVS. Streptococcus suis type 2 was isolated from a brain swab, indicating Streptococcus suis type 2 meningitis.

Streptococcal meningitis was also suspected as the cause of neurological signs in a 14-week-old Large White pig from another unit. The animal became recumbent with paddling and opisthotonos before being euthanased on welfare grounds. Gram-positive cocci were seen in brain stem smears and histology confirmed the presence of a subacute to chronic meningoencephalitis typical of streptococcal infection. However, no bacteria were cultured from the meninges but this was likely to have been due to prior antibiotic treatment.

Ongoing problems with signs of meningitis in 50kg fattening pigs prompted the submission of a carcase for investigation. Post-mortem examination revealed a small increase in peritoneal fluid and moderate meningeal congestion. Culture of liver and lung remained sterile but Streptococcus suis type 2 was cultured in pure growth from brain tissue confirming a diagnosis of streptococcal meningitis.

Systemic Diseases

Bracken Poisoning

A 6-month-old Saddleback pig was found dead in woodland, the second such death in a group of 5 pigs running together. Lungs were heavy and oedematous with approximately 1.5 litres of clear yellow coloured fluid in the thoracic cavity. Mulberry heart disease was initially suspected, but histological examination showed lesions more suggestive of bracken toxicity, and this has been confirmed in this area previously (Harwood et al., 2007. Veterinary Record, 160:914).

Further Reading

- You can view the full report by clicking here.


Further Reading

- Find out more information with ThePigSite's Quick Disease Guide by clicking here.


September 2008