Udder defects and bacterial infection of farmed goats in Hong Kong

Introduction
Unlike for cows and sheep, there is limited literature on udder defects of goats globally and none in Hong Kong. However, it is equally important to investigate udder defects in goats as they are one of the most common species of livestock across the globe. Udder defects can lead to pain or premature culling of does and their offspring, and therefore has important welfare implications. This study was undertaken to address local knowledge gaps by determining the prevalence and types of udder defects in Hong Kong goats, as well as identifying the bacterial species present in their milk and their antimicrobial susceptibility.

Material and methods
Thirty-four does from two smallholder goats farms in Hong Kong were involved. This prospective cross-sectional study utilized non-invasive methods to detect udder defects via visual inspection and palpation of goat udders. Milk was collected for California Mastitis Test (CMT) to screen for mastitis and for microbiological culture to identify udder bacterial pathogens and their antimicrobial susceptibility through Minimum Inhibitory Concentration (MIC) testing. Descriptive statistics were used in this study since qualitative data was involved.

Results and discussion
Udder defects identified include supernumerary teats (69.2%), scabs (7.7%), lumps (7.7%), asymmetry (3.9%), pendulous udder (3.9%), hard gland (3.9%) and subclinical mastitis (3.9%). Species of Staphylococci, Streptococci, Brevibacterium, Corynebacterium, coliforms, Micrococcus luteus and Bacillus arsenicus were detected in the milk samples. Such findings are similar to the types of visible and palpable udder defects, as well as udder bacterial pathogens identified in overseas studies. The MIC results for the tested bacterial isolates of Staphylococcus species showed antimicrobial susceptibility to most antibiotics, but resistance was detected against Doxycycline and Tetracycline in particular, thus careful antibiotic selection of drugs is important for treatment of mastitis to prevent development of antimicrobial resistance.

Conclusion and implications
The pilot data obtained in this study can reinforce overseas literature as it identified similar udder defects and pathogens in Hong Kong goats. Farmers should routinely examine does for udder defects as these can be detrimental to their wellbeing and productivity, predisposing them to further development of mastitis. MIC results indicated there is a wide range of effective treatment options for Hong Kong goat farmers since the Staphylococcus species isolated showed sensitivity towards most of the tested antibiotics. Resistance was however detected against some antibiotics; thus it would be recommended to avoid using these antimicrobial agents when treating mastitis caused by Staphylococcus species. Ideally, local farmers will base the treatment of their goats on milk culture results, interpreted in conjunction with their veterinarian.