Comparison of clinical findings, microbiological results, and farming parameters in goat herds affected by recurrent infectious mastitis

A total of 1388 goats from 31 farms distributed throughout Sardinia, Italy, were investigated in this study. The goat population of Sardinia accounts for a quarter of the entire goat population of Italy. In this work, data and information concerning each farming site were collected, a detailed clinical examination of the udder of lactating animals was carried out, and microbiological examination of milk was performed. Results were then subjected to statistical analysis in order to highlight possible correlations among all findings. Significant results were obtained by comparing clinical findings with bacteriological positivity of milk.Intra-mammary infections were detected in 22.7% of all goats examined. Staphylococcus spp., Streptococcus spp., and Mycoplasma spp. were detected in 73.5%, 9.7%, and 4.7% of positive milk cultures, respectively. Other bacterial genera showed a prevalence lower than 3%. Milk positivity to Staphylococcus aureus was significantly associated to presence in the udder of pustules, ulcers, nodules, and rubor (p < 0.05). Staphylococcus caprae was associated to manual vs mechanical milking, age, udder edema, and absence of mammary secretions (p < 0.05). Staphylococcus epidermidis was positively associated to age (p < 0.05). Streptococcus uberis was associated to mechanical milking, atrophic udder texture, and reactive mammary lymph nodes (p < 0.05). Several other factors showed statistically significant correlations. Taken together, the results presented in this work highlight the specificity, the usefulness, and the practical value of performing a clinical examination of the udder, and suggest its relevance as the most important diagnostic tool for complementing microbiological examination of milk.