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AHVLA Monthly Surveillance Report - May 2011

by 5m Editor
1 July 2011, at 9:12am

UK - Necrotising enteritis due to clostridial enterotoxaemia was diagnosed as a component of increased mortality in neonatal pigs, according to the Animal Health and Veterinary Laboratory Agency's Surveillance Monthly Report for May 2011.

Alimentary tract diseases

Necrotising enteritis

Bury diagnosed necrotising enteritis due to clostridial enterotoxaemia as a component of increased mortality in neonatal pigs on an organic outdoor breeder finisher unit. Pigs were being found dead from one-day-old. In one of three dead piglets submitted, which appeared slightly older than the other two, there was marked diffuse necrosis of the jejunal mucosa for most of its length with one section showing reddening and emphysema of the jejunal wall. Clostridial beta toxin was detected in small intestinal contents, confirming enterotoxaemia. In the other two pigs which were stated to be one-day-old, failure to take in colostrum or milk had led to dehydration and hypoglycaemia. The submitting veterinary surgeon suspected that managemental issues around the time of farrowing were playing a role in the clinical problem.

Brachyspira pilosicoli

A history of persistent scour for two weeks after weaning at six-weeks-old on a farm prompted an investigation by Bury. Lincospectin treatment had given a good response but clinical signs had not been eliminated. Seventy percent of a group of 100 were affected and one euthanased 12 to 14-week-old pig was submitted for necropsy which revealed colitis associated with Brachyspira pilosicoli infection. Histopathology revealed no evidence of PCV-2 associated disease or involvement of Lawsonia species.

Respiratory Diseases

Investigation of increased abattoir condemnations

Seven pigs, approximately eight-weeks-old, were submitted to Starcross to investigate a problem of poor growth rates and increased abattoir condemnations due to pericarditis and pleurisy. Gross lesions in all seven pigs were consistent with the abattoir findings and these were supported by histopathological evidence of pneumonia. Various bacterial agents were isolated from the lungs, including Actinobacillus pleuropneumoniae, Haemophilus parasuis, Bordetella bronchiseptica, Pasteurella multocida, Streptococcus suis, Mycoplasma hyopneumoniae and Mycoplasma hyorhinis. PRRS virus was also identified in one pig.

Pneumonia with complex aetiology

Two batches of finisher pigs close to slaughter were submitted to Thirsk to investigate respiratory disease, ill thrift and increased mortality over a two week period on an indoor finisher unit. A few cases of suspect PDNS were also being seen. Coughing was spreading from pigs derived from one source to others. However, the ill thrift and increased mortality were principally affecting the first source only with approximately 4 per cent of pigs affected and 2 per cent mortality. Pigs were vaccinated for Mycoplasma hyopneumoniae but not for PCV-2. Swine influenza virus (not pandemic H1N1 2009) was detected in both batches of pigs submitted with five of six pigs having significant pulmonary consolidation. Pasteurella multocida was isolated from the consolidated lung in several pigs and infections with Arcanobacterium pyogenes and Streptococcus dysgalactiae subspecies equisimilis were associated with vegetative endocarditis, polyarthritis and a pericardial abscess. In addition, PDNS was confirmed in one pig.PCV-2 associated disease was confirmed by histopathology and immunohistochemistry.

Swine Influenza

Swine influenza due to the pandemic (H1N1) 2009 strain (A/H1N1pdm09) was detected in a pig herd with respiratory signs investigated by Sutton Bonington. Coughing had started in preweaned piglets and continued into the nursery, affecting pigs from two to five weeks of age. The problem was increasing and had been observed over six weaning batches. At weaning, about 50 per cent of pigs were affected and loss of condition was observed in about 10 per cent of these pigs. At necropsy, mediastinal and tracheobronchial lymph nodes were enlarged and one pig had multifocal consolidation of cranial lung lobes. Histopathology revealed a tracheitis and bacterial bronchopneumonia in one pig suspected to be a sequel to swine influenza; Pasteurella multocida was isolated from the lung. Another pig tested positive for A/H1N1pdm09 by PCR, confirming the diagnosis. Rearing units managed on a continuous basis potentially allow persistence of infection long term as the influenza virus continues to cycle in groups of young susceptible pigs.

Neurological Diseases

Streptococcal meningitis

Streptococcal septicaemia/meningitis due to Streptococcus Suis type 2 was diagnosed by Bury in five-week-old pigs on an indoor nursery-finisher on which 18 of 1,500 pigs started showing clinical signs in the 24 hours prior to submission. Meningitis, lameness and swollen hocks were seen with six pigs dying. Two dead pigs were submitted, both had fibrinopurulent arthritis and one had a fibrinous polyserositis. Streptococcus suis 2 was isolated in pure growth from multiple sites including meninges, joints and lung of both pigs. Haemophilus parasuis was also isolated from lung showing cranioventral consolidation, the significance of this organism in the overall clinical picture was uncertain given the widespread detection of Streptococcus suis type 2. No viral involvement was detected.

Other Diseases

Bury diagnosed urinary tract infection due to Actinobaculum suis in a batch of sows which had been served four weeks previously. The sows were on an outdoor 760 sow unit where breeding was by AI. Three of 28 sows in one pen were seen to pass blood in the urine; one of these sows was pale and lethargic whilst another was slightly off colour. A mucohaemorrhagic urine sample was submitted and A.suis was isolated in pure growth consistent with a diagnosis of cystitis/pyelonephritis due to this organism.

Further Reading

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

5m Editor