Infectious and Non-infectious Factors Affecting Somatic Cell Count and New Diagnostic Approaches of Intramammary Infections in Dairy Goats: A Review

Abstract

Background: Intramammary infections constitute major animal health and economic problem in commercial dairy goat farms, being responsible for decreases in milk yield, alter milk composition, and lower milk quality. Objectives: This paper reviews the published literature during the last three decades, highlighting the multiplicity of non-infectious and infectious factors that influence somatic cell count (SCC). Besides that, it intends to contribute to understanding the conventional diagnostic methods and their limitations, and supports the implementation of new technologies for efficient mastitis control, including the use of infrared thermography and ultrasonography. Methods: A search on Medline, ScienceDirect, and University Institutional Repositories databases was performed using “goats, AND mastitis OR intramammary infections OR somatic cells count” for publications from 1990 to present (2020). Results: A total of 144 publications were selected. The SCC is the most important criteria to evaluate the inflammatory status of the mammary glands in goats, but several non-infectious factors (e.g., phenotypic, reproductive, lactational factors) should be taken into consideration for its interpretation. Bacteria and fungi as well as lentivirus are commonly responsive for intramammary infections. Intermittent secretion or environmental contamination of milk pathogens, costs, and time delay poses challenges using conventional diagnostic methods. Ultrasonographic and thermographic techniques applied to the udder seem to be of diagnostic value in acute and chronic mastitis. Conclusions: Unlike other ruminants species, non-infectious factors have a major impact on SCC which should be taken in account for mastitis diagnosis, and according to milk pathogens detection. Further research in imagological techniques is needed to accurately contribute to implant new mastitis control strategies.