Alimentary tract diseases

Salmonella Typhimurium

Bury investigated an incident where twenty percent of 1,500 five-week-old pigs were estimated to be affected with diarrhoea, malaise and approximately 10 per cent mortality from a week after weaning. Three dead pigs were submitted with watery yellow diarrhoea and Salmonella Typhimurium U288 was isolated. All the pigs also had a generalised fibrinous polyserositis from which Pasteurella multocida was isolated together with Streptococcus suis of two types; 2 and 7. It was suspected that viral or other disease may have pre-disposed to the severe mixed infections; however there was no evidence of swine influenza, PRRSV or PCV2 infections. As pigs were described as being unthrifty at the point of weaning, initiating factors early in rear were considered important to explore.

Swine Dysentery

Swine dysentery was confirmed as the cause of yellow mucoid diarrhoea in about 10 of 20 10-week-old pigs on a smallholder unit with 15 sows of mixed breed mainly kept outdoors. Pigs were affected from two weeks post weaning, a few showed weight loss and none died. They responded to tiamulin treatment. The most recent introduction of pigs to the unit were weaners bought from market a year ago. This was the first indication of swine dysentery on the farm and disease manifested in two litters which were mixed, which differed from the usual practice of rearing litters separately. Brachyspira hyodysenteriae was isolated in culture, confirming the diagnosis.

Swine dysentery was also strongly suspected, on the basis of clinical signs and positive B.hyodysenteriae FAT on faeces, to be the cause of diarrhoea with blood and mucus in 20 week-old finishing pigs on an indoor unit with pigs from two sources. Brachyspira organisms isolated are being identified.

Porcine Intestinal Adenomatosis

The carcases of two 15 week old cross-bred pigs were submitted to Shrewsbury for post-mortem examination with a history of diarrhoea followed by loss of body condition. Post-mortem findings included marked thickening of the distal ileum and ascending colon with a thickened and roughened mucosa and the associated lymphoid tissue within the serosa of the intestine was prominent. Examination of MZN smears from the terminal ileum revealed Lawsonia-like organisms in both pigs and histopathology confirmed findings consistent with Lawsonia infection.

Respiratory Diseases

Swine influenza

Concurrent salmonellosis due to Salmonella Typhimurium phage type U288 and swine influenza infection was diagnosed by Bury in 10-week-old pigs on an outdoor rearing site. One kennel of 70 pigs was affected, in this 35 showed disease with 12 dying over a period of three days and with two culled pigs submitted. Pigs were vaccinated against PCV2 and Mycoplasma hyopneumoniae. A severe necrotic typhlocolitis was present consistent with salmonellosis which was confirmed by culture. There was also mild consolidation of cranial and middle lung lobes and PCR (m-gene) detected swine influenza virus in both pigs. The strain involved was not pandemic (H1N1) 2009, but could not be further identified as no virus was isolated by culture for characterisation.

PRRS

Four ten-day-old piglets were submitted to Thirsk as part of an ongoing investigation into increased mortality in a group of pre-weaned pigs. These were born out of a group of sows that had earlier experienced abortion problems. PRRSv was initially suspected but not confirmed in the aborted foetuses. The description on farm was of classic signs of PRRS with abortions and early farrowing occurring in sows, blue ears, fever spikes and piglet mortality. Post-mortem examination of the four pigs revealed a polyserositis in two of the pigs and marked purple interlobular oedema and consolidation of the craniodependent portion of the lungs in the other two. PRRSv was demonstrated by PCR in three out of the four pigs. This confirmed a PRRS-driven problem with secondary bacterial disease such as Haemophilus parasuis polyserositis and salmonellosis. The scale of the problem on the farm was quite remarkable and reminiscent of the initial descriptions of PRRS in the previous century.

Other diseases

Streptococcus suis

Langford diagnosed Streptococcus suis serotype 2 as a cause of sudden death and arthritis with joint swelling on two pig units. On one of these, a 2,000 place rearing unit, approximately 50 seven-week old pigs were said to be affected and six had died. On the other, three eight-week old piglets in a group of 400 developed hot, swollen and painful hock/carpal joints prior to death. Streptococcus suis serotype 2 also caused CNS signs before death in at least eight weaners out of a group of 40 in a small breeder-fattener herd.

Further Reading

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