0
Throughout the study, there was an analysis of tissue samples from a total of 83 affected (n=41) and unaffected (n=42) pigs between 7 and 120 day old, from 38 different farms with a history of increase in MHD cases among nursery pigs with 1% to 10% of the animals having been affected by sudden death or macroscopic lesions (enlarged heart with transmural haemorrhages, ascites, enlarged liver). The samples were analyzed for levels of vitamin E, as well as selenium, cadmium, chrome, cobalt, copper, iron, magnesium, manganese, molybdenum, phosphorus, potassium, selenium, sodium and zinc. The samples were also tested using PCR assays to detect pan-morbillivirus, pan-coronavirus, pan-pestivirus, porcine enterovirus (PEV), pan-herpesvirus, porcine circovirus type 1 (PCV1), porcine circovirus type 2 (PCV2), porcine parvovirus (PPV), European and North American porcine reproductive and respiratory syndrome virus (PRRSV), Bungowannah virus (BGWV) and West Nile virus (WNV).
Among affected and unaffected pigs, no significant differences were found in levels of magnesium, phosphorus, and selenium in heart tissues only, copper in liver tissues only, and potassium, calcium, chromium, manganese, iron, cobalt, zinc, molybdenum and cadmium in both heart and liver tissues. However, significant differences (P < 0.05) were observed in levels for sodium (1,441.8 ± 39.4 versus 1,615.8 ± 25.2), copper (4.6 ± 0.2 versus 3.9 ± 0.2) and vitamin E (2.4 ± 0.6 versus 4.4 ± 0.6 in) in heart tissues and sodium (1,586.6 ± 44.8 versus 1,805.0 ± 55.3), magnesium (177.8 ± 4.1 versus 159.2 ± 3.0), phosphorus (2,516.9 ± 55.4 versus 2,363.2 ± 50.6), selenium (1.1 ± 0.1 versus 0.7 ± 0.1) and vitamin E (3.7 ± 1.3 versus 7.9 ± 1.3) in liver tissues. Interestingly, the mean values were often higher in affected pigs compared to non-affected pigs. The difference between affected and unaffected groups observed among heart vitamin E, liver vitamin E, and liver selenium is in agreement with the traditional etiology of MHD. the MHD pigs in this study did have significantly (P < 0.05) lower liver selenium than MHD negative pigs, although it still remained within the normal range for healthy pigs, as with vitamin E, which was also found to be within a normal range. This can be explained as being an effect of the etiology of MHD.. In addition to selenium and vitamin E, several other minerals varied significantly between affected and unaffected groups. While uncertain, it is possible that this could be explained by mineral losses in the course of cardiomyocyte necrosis.
In relation to the pathogens, the affected pigs had a trend for a higher incidence of PCV2 (P = 0.45), PEV (P = 0.25), and pan-herpesvirus (P = 0.25). . In this study no pathogen has been linked to MHD
While the etiology of MHD and its relationship to vitamin E and selenium is still not completely understood, the data generated from this study shows that selenium deficiency is associated with the disease. Furthermore, while the data is not strong enough to point to a definitive pathogen associated with MHD, there does seem to be a relationship between MHD and PEV and herpesvirus.
P.R. Thomas, G. Bortoletto, P.D. Kirkland, W. Kim, A.T. Loynachan, S. M. Ensley, T. Opriessnig. Assessment of vitamin E levels, selenium levels and presence of viral pathogens as the etiology of mulberry heart disease. 2010 AASV Annual Meeting: Implementing Knowledge: 73-74.
