An investigation into the analytical, cytotoxicity and immunotoxicity of mycotoxins found in commercially available pelleted pet foods in Durban, South Africa.

Abstract

Introduction: Dry pelleted dog food in the South African market is available via supermarket, pet stores (standard brands - SB) and veterinary channels (premium brands-PB). Similarly, cat food were viewed in two market segments. Methodology: Representative feeds from both categories were analysed for four main mycotoxins viz. aflatoxins (AF), fumonisin (FB), ochratoxin A (OTA), and zearalenone (ZEA) using standard well-described extraction, characterisation and quantitation processes. Results: All foods showed contamination with fungi (mainly Aspergillus flavus, Aspergillus fumigatus and Aspergillus parasiticus) and mycotoxins (the most prevalent being aflatoxins and fumonisins), irrespective of the brand. This study determined the immunotoxicity of extracts from pelleted dog and cat feed for mycotoxins. Isolated dog peripheral blood mononuclear cells (PBMCs) were treated with feed extracts to determine mitochondrial function, oxidative stress, and markers of cell death using luminometry and flow cytometry. Glutathione was significantly depleted by SB extracts. Markers of apoptosis and necrosis were elevated by both SB and PB feeds when compared to controls, with SB extracts being significantly higher than PB. ATP levels decreased with increased mitochondrial depolarization in cells that were exposed to both feed extracts with SB showing the greatest differences when compared to the control. Cat peripheral blood mononuclear cells (PBMCs) were isolated and treated with various feed extracts to determine oxidative stress (TBARS and GSH assay), mitochondrial integrity and cell death (Luminometry and Flow cytometry). Both PB and SB extracts showed significantly decreased ATP levels and increased mitochondrial depolarization except for the PB acid fraction. Lipid peroxidation was significantly increased in both PB and SB extracts with a concomitant decrease in GSH levels. Phosphatidylserine externalization and necrosis levels were increased in both PB and SB extracts when compared to the control. Executioner caspases-3/7 was also elevated following extract exposure except for the PB acid fraction. Conclusion: There were high levels of fungal contamination and mycotoxins in both categories of feed, regardless of the notion that higher priced PB’s were of a higher quality.