ASSOCIATION OF TUMOR-NECROSIS-FACTOR AND ACUTE-PHASE REACTANT CHANGESWITH POST ARRIVAL DISEASE IN SWINE

Severe weight loss in the absence of respiratory, enteric or systemic clinical disease or gross pathologic lesions is often observed when im munologically naive boars are placed in conventional health swine faci lities. Affected animals develop this weight loss in spite of receivin g pre-entry vaccinations against common swine pathogens, such as Haemo philus parasuis or Mycoplasma hyopneumoniae. In many cases, the weight loss is non-responsive to long term and biotic therapy. In order to d etermine the relationships between the severity of post arrival weight loss and disease and its potential immunological or physiological ind icators, tumour necrosis factor (TNF) and acute phase reactant levels were correlated with the clinical status in immunologically naive boar s following their transfer to a conventional facility. Boars had highe r TNF (P < 0.0001) and plasma protein (P = 0.0054) levels and decrease d zinc (P = 0.0004) levels during periods of clinical sickness. Likewi se, peak and average plasma TNF, serum haptoglobin, and serum zinc wer e correlated indicating a prolonged stress or pathogenic insult (r = 0 .89, P < 0.0001 for TNF; r = 0.67, P = 0.01 for haptoglobin; r = 0.73, P = 0.005 for zinc). An acute phase response, a systemic TNF increase and the development of a lymphopenia were observed in post arrival di sease in swine. This is the first time cytokines and acute phase react ants have been investigated in a field study involving immunologically naive or high health swine.