Bovine mastitis is an inflammatory disease of the udder that causes important economic losses in the animal breeding and dairy product industries. Nowadays, the conventional livestock antibiotic treatments are slowly being replaced by alternative treatments. In this context, the main aim of this study was to evaluate the efficacy of natural products in alternative treatment of bovine mastitis. Two natural formulations with previously suggested in vitro antimicrobial effect were tested in vivo on mastitic cows. Animals with a positive diagnosis for mastitis (n = 20) were divided into three treatment groups: two groups (n = 8) were administered formulations of propolis, alcoholic extracts of Brewers Gold and Perle hops, plum lichen, common mallow, marigold, absinthe wormwood, black poplar buds, lemon balm, and essential oils of oregano, lavender, and rosemary designated R4 and R7 (differing only in the latter being more concentrated) and one group (n = 4) a conventional antibiotic mixture. In vivo efficacy of treatments was evaluated by somatic cell and standard plate counts, the treatment being considered efficacious when both parameters were under the maximum limit. R7 was effective in the most cases, being therapeutically bactericidal in six out of eight cows, while R4 gave good results in three out of eight cows, and conventional antibiotics cured one out of four. These results suggest the possible therapeutic potential of these natural products in bovine mastitis.

Two cytopathic agents were isolated on porcine alveolar macrophages following inoculation with homogenates of lung tissues from pigs showing respiratory problems. These isolates were identified as porcine reproductive and respiratory syndrome (PRRS) virus isolates by indirect immunofluorescence using a PRRS virus (PRRSV) specific monoclonal antibody (MAb) and were designated as LHVA-92-1 and LHVA-92-2. Immunogold electron microscopy using a porcine PRRS positive serum pool and protein A-gold resulted in an intense labelling of aggregates of viral particles. Dark specific cytoplasmic staining of porcine alveolar macrophages infected with both virus isolates could be observed by immunogold silver staining (IGSS) using the specific MAb. This method proved effective in detecting PRRSV antigens in several ethanol-fixed tissues of piglets intranasally inoculated with the supernatants of macrophages infected with each isolate. Immunogold silver staining was also successfully used for the detection of PRRSV antigens on sections of formalin-fixed paraffin-embedded lung tissues and on frozen sections of lungs. The present results indicate that colloidal gold may be useful for the identification and immunohistochemical detection of PRRSV in tissues.