Histopathological and virological findings in emaciated pigs from Mexico: an exploratory study

Abstract

The objective of this work was to detect the presence of three main pig respiratory viral agents (porcine rubulavirus [PorPV], porcine circovirus type 2 [PCV-2], and porcine reproductive and respiratory syndrome virus [PRRSV]) in tissues of emaciated piglets from the Bajío Region (Mexico). Necropsies and histopathological studies of 37 pigs with poor body condition were performed; viruses were detected by molecular biology methods and PCV-2 was further assessed by immunohistochemistry (IHC). Histopathologically, interstitial pneumonia was observed in 25/37 (68%) of the piglets. Also, a varying degree of lymphocyte depletion in lymphoid organs was found in 14/37 (38%) animals. Through polymerase chain reaction (PCR) and/or reverse transcription polymerase chain reaction (RT-PCR), from the 37 pigs, 16 were positive for PCV-2, 18 for PRRSV and 1 for PorPV. In accordance with these results, the infection and/or co-infection with PCV-2 and PRRSV were fairly frequent findings in piglets with poor body condition in Mexico, while the infection by PorPV was apparently negligible. Wasting of post-weaning piglets is a global pig farming problem that causes great economic losses and has been associated with diverse factors: microbial agents, environmental factors, nutritional factors, and management. When the Blue Eye Disease was first reported in Mexico, it was associated with severe wasting in post-weaning piglets. This study demonstrated that this disease does not seem to play such an important role in the wasting as was previously thought.