Abstract:
Mastitis in cattle is a complex and multi-factorial disease caused by an interaction between three
major factors: the animal, pathogens, and the environment. A cross-sectional study was conducted
from June 2022 to November 2022 to estimate the prevalence of mastitis in lactating cows, to
assess the risk factors for bovine mastitis, and to isolate and identify coliform and gram-positive
cocci bacteria involved in the mastitis cases from dairy farms in Dire Dawa, Eastern Ethiopia.
Detection of mastitic animal was done based on physical examination of udders and CMT test.
Bacterial culture and biochemical tests were employed to identify the target pathogens. A total of
366 dairy cows and 1,464 quarters were screened for mastitis. Overall prevalence of mastitis at
cow and quarter levels were 24.04 and 13.5%%, respectively. Age, parity, cows udder position,
history of mastitis, barn floor, milking sequences of clinically mastitic cows and leg and udder
hygiene scores were found to be risk factors significantly (P<0.05) associated with mastitis. From
the 191 mastitis-positive milk samples 82.7% (158/191) were culture positive. Out of the isolates
from clinical cases (n=59) and isolates from sub clinical cases (n=99), Staphylococcus aureus
(22%) and E. coli (15.7%) were predominant isolate. The other bacterial isolate in order of
abundance, Coagulase Negative Staphylococcus (10.5%), Streptococcus agalactiae (6.8),
Streptococcus dysgalactiae (5.8%), Staphylococcus intermedius (4.7%), Staphylococcus hyicus
(4.2%), Klebsiella pneumoniae (3.1%), Micrococci spp (2%), Streptococcus uberis (1.6%),
Enterobacter aerogenes (1%), and Enterococci spp (0.5%). The study showed that high parity
number (OR = 19.5; p = 0.005), moderate parity (OR = 10.9; p = 0.022) and history of mastitis
in preceding lactation (OR = 28.4; p = 0.001) were the major risk factors which are significantly
associated with higher prevalence of S. aureus. History of mastitis in preceding lactation (OR =
3.7; p = 0.021) and very dirty (OR = 3.9; p = 0.005) udder and legs were the major risk factors
which are significantly associated with higher prevalence of E. coli. Therefore, hygienic milking
practice, adequate sanitation of the dairy environment, proper attention to the health of mammary
glands and regular screening tests should get emphases as control strategies
