Veterinary Services

Nutritional and metabolic disorders

Iron deficiency anaemia was diagnosed in several pale, thin piglets that had clearly failed to receive routine iron injections.

Generalised and systemic conditions

Isoimmune thrombocytopaenic purpura was diagnosed as the cause of marked skin discolouration and death in a two-week-old pig. As is typical of the condition, four of the largest pigs in one particular litter of ten had been similarly affected. No other litters were affected and advice was given regarding avoiding this particular mating combination in future.

Meningitis-like signs in three-week-old pigs on an outdoor unit prompted submission of one affected animal. Gross post mortem examination revealed a suppurative polyarthritis and meningitis and Streptococcus suis serotype 1/14 was isolated from the brain and joints. Dramatic spread of S. suis serotype 14 (and 1/14) throughout the industry was experienced in the 1990's, but there have been few new herd outbreaks in more recent years. The source of the infection in this particular case is not known although introduction of a carrier boar would seem most likely.

Examination of a 40kg pig from an organic unit reporting "sudden" deaths in late growers and early finishers revealed evidence of carcase dehydration, generalised lymph node enlargement and marked enlargement of the kidneys. A number of affected pigs had shown skin lesions suggestive of porcine dermatitis and nephropathy syndrome (PDNS). Although there was no obvious evidence of skin lesions in this case, histopathological examination of kidney tissue confirmed PDNS as the diagnosis. Widespread chronic glomerulonephropathy with interstitial fibrosis was noted, consistent with PDNS that has had a chronic progressive course. The lymph nodes and spleen showed extensive lymphadenitis with necrosis and oedema, thought to be terminal changes associated with toxaemia. Post-weaning multisystemic wasting syndrome (PMWS) had previously been a problem on this unit but mortality among younger age groups was now under five percent.

Four eight-week-old pigs were submitted from a nursery unit which had been experiencing increased mortality and wasting. Three of the pigs were dull, depressed and recumbent. Gross post mortem examination of one pig revealed marked hydrothorax, pneumonia (Pasteurella multocida was isolated from lung), pleurisy and pericarditis together with histopathological lesions in lymphoid tissues consistent with PMWS. A Streptococcus spp. (not identified, but biochemically similar to S. mitis) was isolated as a scant growth from the brains of two pigs and from the hock joint of one pig. Neuropathological examination confirmed the presence of bacterial meningitis and choroiditis. It is possible that the immunosuppressive effects of PMWS in the herd were allowing organisms not usually involved as primary pathogens to cause a variety of lesions.

Alimentary tract disorders

Two sixteen-day-old piglets were examined from an indoor unit experiencing mortality in approximately 50% of litters between seven and 21 days of age. Affected piglets were reported to be the biggest in the litter. Most apparently died without preceding clinical signs, except a terminal yellow scour. Post mortem examination revealed congestion of the small intestine with creamy yellow contents. High Isospora suis oocyst counts (17000 oocysts per gram) were found on examination of colonic contents. Histopathological examination also identified areas of focal mucosal necrosis in the small intestine associated with clostridial infection. A diagnosis of concurrent coccidiosis and acute clostridial enteropathy was made, the latter infection accounting for the acute clinical course and higher mortality observed.

Rotaviral diarrhoea was confirmed as the cause of widespread scour in four-day-old piglets on one unit. Alteration of the farrowing house cleansing and disinfection programme appears to have prevented continued cases.

Scour and some deaths among growers on a unit that had undertaken a segregated disease control programme (partial depopulation) sixteen months previously in order to eliminate enzootic pneumonia and swine dysentery, prompted fears of a recrudescence or breakdown involving swine dysentery. Examination of three affected pigs revealed gross and histopathological lesions consistent with proliferative enteropathy in two of the pigs (in one pig lesions were restricted to the colon and caecum) and a mixed bacterial colitis associated with PMWS in another animal. No microscopic or bacteriological evidence of Brachyspira spp. involvement was detected.

Salmonella Typhimurium phage type 104 was isolated on direct culture of a pooled faeces sample from a group of finishing pigs with a three day history of scour and weight loss. Although no other enteropathogens were isolated from the sample, the significance of the isolation is not clear and submission of affected animals for post mortem examination was recommended.