Veterinary Services

Generalised and systemic conditions

Several one-week old piglets were submitted from a herd where there was concern that there had been a flare up of PRRS. Over the previous two weeks some of the piglets born were weak, with low viability and some had paper-thin skin. It was reported that some of the sows had blue ears and that appetite had been reduced. The gilts on the unit were vaccinated against PRRS before farrowing but the adult stock was not vaccinated thereafter. The piglets showed a widespread subacute interstitial pneumonia consistent with a viral-type insult. One piglet also had multifocal chronic abscesses in the myocardium, with gram-positive cocci in the lesions. Streptococcus dysgalactiae was isolated in systemic culture from this and another of the young piglets. Serology on older growing pigs was strongly seropositive for PRRS virus.

Three 25-day-old pigs were submitted to investigate the cause of a neurological condition that had affected seven pigs from three litters, two of which had died. Lesions included meningitis, pneumonia affecting the apical lung lobes and polyarthritis associated with Streptococcus suis serotype 1/14.

Two 19 to 22 kg pigs were submitted to investigate an ill-thrift problem and a slight cough in the group. Findings were subacute enzootic-type pneumonia with more acute exudative pneumonia and early pleurisy associated with Streptococcus suis serotype 7. The lymphoid tissues of both pigs showed evidence of postweaning multisystemic wasting syndrome (PMWS).

Alimentary tract disorders

Three six-hour-old piglets were submitted to investigate an increase in mortality rate in the farrowing house due to piglets with poor viability. Two piglets had hyperaemia of the jejunum and a diphtheritic membrane covering the jejunal mucosa. The small intestinal contents were blood tinged and the mesenteric lymph nodes appeared oedematous in each case. The renal cortices were pale and there were numerous petechiae in the cortices. The findings were suspicious of Clostridium perfringens type C infection and this was confirmed by clostridial toxin ELISA testing.

A scour problem of two weeks duration was reported in a group of ten-week-old pigs. The scour had continued despite medication with chlortetracycline and resulted in uneven growth rates. Postmortem examination on two pigs showed typhlocolitis associated with profuse colonisation by spirochaetes. Brachyspira pilosicoli were isolated from both pigs confirming a diagnosis of spirochaetal typhlocolitis.

Four outbreaks of swine dysentery were confirmed in growing and finishing pigs, in units not previously known to have the disease. In one outbreak, there was 10 percent mortality in four-month-old pigs and all 880 growing and finishing pigs in the unit were reported to be scouring. Co-infection with cryptosporidia (large numbers in small intestine) was evident in one outbreak, while no co-infections were detected in the other three.

Two 15-week-old fatteners were submitted for postmortem examination to investigate the cause of greenish scour in one group. The pigs were vaccinated against porcine proliferative enteropathy. Both pigs had chronic active granulomatous enteritis and colitis associated with Yersinia enterocolitica infection. Examinations for other enteropathogens by PCR and culture proved unrewarding. Yersiniosis was considered to be the cause of the enteritis in this case.

A piece of grossly thickened ileum was collected in the abattoir from a five-month-old finisher to investigate the cause. Histopathology showed well-established lesions of proliferative enteropathy, with epithelial hyperplasia and abscessation affecting many of the crypts. There was also hyperplasia of the submucosal lymphoid tissue associated with the mucosal lesions. Silver-stained sections showed intracellular bacteria consistent with Lawsonia intracellularis infection.

Salmonella Typhimurium DT194 was isolated from four out of 35 faecal samples screened as part of the ZAP Salmonella programme on an indoor unit. Advice on salmonella control strategies was offered.

Respiratory tract disorders

Variable growth rates among growing pigs were investigated on one unit. There was considerable coughing in the farrowing house and at all stages of growth. The herd was previously free of enzootic pneumonia (EP) and no vaccines were used. Three pigs, weight range 10 to 14kg, were euthanased for postmortem examination. All had gross and histopathological lung lesions suggestive of EP, complicated by bacterial infection. Bacteriology from the lung tissues confirmed the following infections among the piglets - Pasteurella multocida, Streptococcus suis serotypes 3 and 22, Arcanobacterium pyogenes and Actinobacillus pleuropneumoniae.

An outbreak of coughing in finishing pigs was associated with swine influenza combined with exudative bronchopneumonia and pleurisy. The herd was classed as free from enzootic pneumonia and porcine reproductive and respiratory (PRRS) virus infection, and testing confirmed that the unit’s health status had not changed in respect of the latter two infections.

Reproductive tract disorders

Investigation of abortion in a sow showed changes in the placenta suspicious of chlamydial involvement. The placenta was grossly thickened (resembling an EAE placenta in sheep) and this was the second time this animal had aborted. There were intracellular acid-fast organisms present in placental MZN smear, and histology showed exudative placentitis and vasculitis similar to those in chlamydial placentitis in sheep. Gram-stained sections showed no evidence of other forms of bacterial infection. The farm also has a lambing ewe flock in which chlamydial abortion has been diagnosed.