Prevalence of mastitis and antimicrobial resistance patterns of Escherichia coli and Staphylococcus aureus isolated from the infected udder of dairy cows in coastal regions

Identification of risk factors is important for the design of control programmes for mastitis in cows. Information about farms and management was collected at a farm visit. California Mastitis Test (CMT) was performed to assess sub-clinical mastitis, and cows, udder and milk were examined for clinical mastitis. A total of 347 lactating cows from 83 farms in the dry season (November - February) and 388 lactating cows from 89 farms in the wet season (June - October) were studied. The overall prevalence of mastitis was 19.9% and 44.8% in dry and wet seasons, respectively. The prevalence of mild mastitis was 17.3% and 40.7%, whereas that of moderate mastitis was 2.6% and 4.1% in dry and wet seasons, respectively. The prevalence of mastitis was higher (P<0.01) in wet than in dry season. On average, 18.7% quarters had mastitis during the wet season and 6.9% in the dry season. In the dry and wet seasons, respectively, 63.9% and 11.2% had completely dry floors, and the prevalence of mastitis was 22.6% and 30.0%. On the other hand, 88.8% and 36.1% of 83 farms had partly or completely wet and soiled floor and the prevalence of mastitis was 40.0% and 59.5% in the dry and wet seasons, respectively. Udder cleanliness, milk yield and peri-parturient diseases significantly (P<0.01) increased the risk of mastitis. The prevalence of mastitis is regarded as quite high. Dry and clean floor to keep cow's udder and teat clean would help control mastitis in the dairy farms of Bangladesh. DOI: 10.3329/bvet.v26i2.4951 Bangl. vet. 2009. Vol. 26, No. 2, 54-60

Mastitis poses a major challenge in dairy cattle farming as it leads to production and economic losses. Some mastitis causing bacteria have shown resistance to some antibiotic and the risk factors associated with the antimicrobial resistance (AMR) are not well understood. The current study assessed the prevalence and risk factors associated with occurrence of mastitis in dairy cows kept by small-holder farmers in Githunguri Sub-County, Kenya. Further, susceptibility of the isolated Staphylococcus aureus and Escherichia coli to commonly used antibiotics was evaluated. The study design was cross sectional where 91 milk samples from 40 farms were sampled from two wards in the study area. Structured questionnaires were used to assess risk factors of mastitis. The milk obtained from lactating cows was first subjected to California mastitis test (CMT) and then taken to microbiology laboratory for isolation and identification of Staphylococcus aureus and Escherichia coli using standard bacteriological tests. Antibiotics sensitivity of the isolated bacteria was examined using disc diffusion method. Based on CMT, the overall prevalence of mastitis was 50.5%. The prevalence of mastitis was associated (p<0.05) with hygiene levels, being highest (69.2%) in the dairy cattle whose udder and leg hygiene were dirty. Highest prevalence of mastitis (p<0.05) was found in cows who were not milked regularly (52.4%) compared to those who were milked regularly (47.6%) (p<0.05). Cows which were cleaned using bore hole water had higher prevalence (53.3%) of mastitis compared to those cleaned using tap water (46.7%) (p<0.05). Cows that produced between 21-30 liters of milk per day had the highest prevalence (66.7%) of mastitis, while those producing between over 30 liters milk per day had lower prevalence (25%) (p<0.05). The prevalence of S. aureus and E. coli were 30.8% and 12.1%, respectively. Staphylococcus aureus isolates showed varied resistance to all the tested antibiotics with the highest resistance being against Oxytetracycline (57.7%) and Tetracycline (38.5%) but were sensitive to Vancomycin (100%), Ampicillin (100%), Chloramphenicol (96.2%), Penicillin (92.3%) and Gentamycin (92.3%). All the Escherichia coli isolates were sensitive to Chloramphenicol, Kanamycin, Gentamycin and Oxytetracycline but were resistant to Ampicillin (88.9%) and Vancomycin (88.9%) amongst other antibiotics. In conclusion, half of the sampled cows had mastitis whose risk factors was associated with poor hygiene and irregular milking of the cows. The isolated bacteria showed varied resistance to commonly used antibiotics. To reduce the prevalence of the mastitis and AMR, there is need for extension service workers to train farmers on improved management of the mastitis.

Bovine mastitis remains a major prevalent disease in cattle and places a significant economic burden on the global dairy industry. The goal of this systematic review and meta-analysis was to examine the overall prevalence of mastitis and its associated risk factors among dairy cows. Scientific articles written in English were recovered from PubMed, ScienceDirect, Web of Science, Google Scholar, Cochrane Library, and other sources from Google Engine and University Library Databases. “Prevalence,” “bovine mastitis,” “clinical mastitis,” “subclinical mastitis,” “associated factors,” “dairy cows,” and “Ethiopia” were search terms used for this study. For critical appraisal, PRISMA 2009 was applied. Heterogeneity and publication bias were evaluated using Cochran's Q, inverse variance (I2), and funnel plot asymmetry tests. A random-effects model was used to calculate the pooled burden of mastitis and its associated factors among dairy cows, along with the parallel odds ratio (OR) and 95% confidence interval (CI). A total of 6438 dairy cows were included in the 17 eligible studies for this meta-analysis. The overall pooled prevalence of mastitis among dairy cows in Ethiopia was 43.60% (95% CI: 34.71, 52.49), of which 12.59% (95% CI: 7.18, 18.00) and 32.21% (95% CI: 24.68, 39.74) were clinical and subclinical cases, respectively. Of the regions, the highest and lowest pooled prevalence estimates of mastitis among dairy cows were 49.90% (95% CI: 31.77, 68.03) and 25.09% (95% CI: 3.86, 46.32) in the Oromia and Amhara regions, respectively. The highest pooled prevalence estimate in the study period was recorded between 2017 and 2022, with a pooled prevalence estimate of 46.83% (95% CI: 35.68, 57.97), followed by the study period from 2005 to 2016, with a pooled prevalence estimate of 39.97% (95% CI: 25.50, 54.44). Gram-positive bacteria (84.70%) were the most prevalent mastitis-causing agents compared with Gram-negative bacteria (15.30%). Breed (AOR: 2.17, 95% CI: 1.44, 2.90), lactation stage (AOR: 1.59, 95% CI: 1.04, 2.15), parity (AOR: 3.31, 95% CI: 1.69, 4.94), history of mastitis (AOR: 3.56, 95% CI: 2.40, 4.71), floor type (AOR: 1.59, 95% CI: −0.16, 3.34), and teat injury (AOR: 6.98, 95% CI: 0.33, 13.64) were factors significantly associated with mastitis among dairy cows in Ethiopia. Early diagnosis and proper medication, as well as implementing appropriate prevention and control measures, are necessary for the management of mastitis in dairy cows.

Mastitis is among the most prevalent disease that contributes for the reduction of milk production in dairy herds. Although several published studies have estimated the prevalence of mastitis, variation among studies is great. The objective of the present meta-analysis was to provide a pooled estimate of the prevalence of overall, clinical, and subclinical mastitis in dairy cattle in Ethiopia. A pooled estimate was also conducted by potential risk factors. The literature search was restricted to studies published in English language from January 2002 to June 2016. Meta-analysis of 39 studies was done under random effects model using metafor package in R software. The pooled estimate of the overall prevalence of mastitis on cow-basis was found to be 47.0% (95% confidence interval [CI] = 42.0, 52.0). The pooled prevalence with the 95% CI for clinical and subclinical mastitis was 8.3% (95% CI = 6.5, 10.3) and 37% (95% CI = 32.9, 40.7) respectively. There is a statistically significant and high heterogeneity of the prevalence estimates between published studies. The odds of occurrence of mastitis were higher in cows at early (odds ratio [OR] = 1.6; 95% CI = 1.4, 1.8) and late lactation (OR = 1.3; 95% CI = 1.2, 1.5) than mid lactation, in cows with 3-4 (OR = 1.5; 95% CI = 1.4, 1.7) and >4 parity number (OR = 2.9; 95% CI = 2.6, 3.4) than those with 1-2 parity number. Previous history of mastitis, floor type, milking hygiene, and udder injury had also statistically significant effect on pooled prevalence of mastitis (P < 0.05). The present study reported that there is high prevalence of mastitis in dairy cows in Ethiopia, which could contribute to the low productivity in lactating cows. The statistically significant association of risk factors such as floor type, milking hygiene, and presence of udder injury with mastitis may suggest that dairy farmers can reduce the occurrence of the disease by improving their management practices.

A cross-sectional study was carried out from January 2023 to February 2023 to study the prevalence of bovine mastitis (Clinical and sub –clinical), risk factors, to isolate and identify major pathogens and to make antimicrobial susceptibility test on the isolates on cross breed lactating cows which kept under intensive farming /husbandry/ system found in Barek and Sululta town. A total of 200 lactating cows examined 66 from Sululta, 71 from Wuchale and 63 from Debre libanos for mastitis by screening test/California Mastitis Test/ for sub clinical and udder observation and palpation for clinical mastitis from 9 kebeles which found in sululta, Wuchale and Debre libanos. The overall prevalence of mastitis was 57 (28.5%), where lower in Sululta and Debrelibanos districts 16(24.24) and 15(23.80) respectively and higher in Wuchale distirict 26(36.61) by clinical and sub clinical type of mastitis. From cultured samples, the bacteria genera species and isolated were as in with high prevalence were Staphylococcus intermidius 35(71.43), Staphylococcus aureus 6(12.25), E.coli 1(2.04). Coryne bacterium (6.12%) and Bacillus cereus 4(8.13). From currently tested few isolates using selected antimicrobial agents, all susceptible for Chloramphenicol and Gentamycin except one each isolates of S.aureus and for both which shows intermediate. Similarly, most of the isolates susceptible to Erythromycin and Amoxicillin except some isolates of Staphylococcus aureus, and bacillus cereus. However, high resistance was observed by most of isolates to Penicillin and tetracycline. Those cows with different lactation stage and farming system revealed significant difference (p&lt;0.05) in prevalence of mastitis. The prevalence of both age and parity by risk factors were insignificance (P&gt;0.05), however, there was significance difference between semi intensive and extensive farming system (P&lt;0.05). Prevalence of mastitis, particularly, the subclinical one could bring about major economic losses in dairy cows without notice as result of reduced milk production, poor growth or mortality of suckling calves and dam health. The resistance to penicillin and tetracycline were observed with poor efficacy may be due to prolonged and indiscriminate usage these antimicrobials in the area so that Chloramphenicol, Gentamycin and Erythromycin could be the drugs of choice in the present study.

IntroductionMastitis is an inflammation of the mammary gland that could either be clinical or subclinical, and can be caused by infectious agents. It has different aetiological pathogens such as Staphylococcusaureus, Streptococcusagalactiae, Escherichia coli that pose different economic and health impacts. In Ethiopia, previous studies on mastitis have been focused on semi‐intensive and intensive dairy production system. The objectives of this study were therefore to estimate prevalence, aetiology of causative pathogens and identify different risk factors of mastitis in extensive management systems. A total of 532 lactating cows were randomly selected for a cross‐sectional study carried out in four districts of west Wollega, western Oromia, Ethiopia.ResultBased on the clinical examination and California mastitis test, 39.67% overall prevalence of mastitis on cow level was recorded. Of them, 16.70% and 22.70% were clinical and subclinical mastitis, respectively. Among 2,128 quarters examined 210 were blind teats. The associated risk factors age ≥8 years (16.35%), parity 1–3 calving (27.63%), milk yield 1–2 litres (21.98%), lactation stage <4 months (18.04%) and tick infestation (26.70%) were significantly associated in the occurrence of mastitis. Staphylococcus spp. (15.60%) were the dominant bacteria isolated from collected mastitic milk.ConclusionMastitis is an important disease for dairy cows kept under an extensive management system. Its occurrence is determined by risk factors like age, parity, milk yield, lactation stage and tick infestation. This study is indicated Staphylococcus species as the major bacteria isolated from mastitic milk. This study warrants further study on the prevalence, aetiology, economic impact and potential risk factors of mastitis in dairy cows kept in extensive production system.

A cross-sectional study was conducted from December 2019 to July 2020 on the prevalence of bovine mastitis, risk factors, and isolation of major causative pathogens in and around Hargeisa, Somaliland. The study was carried out on 384 dairy cows. Based on clinical examination, the California mastitis test (CMT), and isolation of bacterial pathogens using standard techniques, the overall prevalence of mastitis was 28%. Among them, 78.7% had subclinical mastitis, whereas 21.3% had clinical mastitis. At quarter level, 414 quarters were examined, and the overall prevalence was 37.7%. The prevalence of blind teats was 2.6% due to the absence of 40 teats during a physical examination. The current study found that the prevalence of mastitis was statistically significant and associated with age, parity, lactation, and previous history of mastitis. On a bacterial examination of the milk sample, the most isolated bacteria was Staphylococcus aureus, which scored 42.5%, while micrococci (13.8%) were the least identified bacteria. The conclusion of this study revealed that there is a high prevalence of mastitis, particularly subclinical mastitis, in the study area. Awareness creation and increasing animal health services, especially regular screening, prevention, and treatment strategies for mastitis, should be needed.

A cross-sectional study was conducted on 316 lactating dairy cows from November 2021 to May 2022 in and around Modjo. The main objectives of this study include estimating the prevalence and isolation of aerobic bacterial pathogens and observing compositional changes in mastitic milk. To this end, mastitis was diagnosed both clinically and using California mastitis test (CMT). Isolation of major aerobic pathogens and alterations in milk composition were determined using their respective standard techniques. Accordingly, the overall prevalence of mastitis observed in the study was 72.8%, of which 9.5% was clinical and the rest 63.3% subclinical mastitis. Quarter level prevalence was 45.2%. Among the potential risk factors considered, the presence of teat/udder injury, poor udder and farm hygiene showed higher prevalence of mastitis (p &lt; 0.05) compared to the corresponding categories. The most predominant bacterial pathogen isolated was Staphylococcus aureus (11.25%), followed by E. coli (10%), Micrococcus species (10%) and Pseudomonas aeruginosa (10%). Protein, solid non-fat (SNF), pH and freezing point measurements showed statistically significant difference (p &lt; 0.05) between milk from mastitic and non-mastitic udders. However, fat and density were not statistically different (p &gt; 0.05). In conclusion, mastitis was highly prevalent and clinically important disease of dairy cows in the study area and hence deserves attention to minimize its impact. Cows’ udder and farm should be kept clean as much as possible to reduce the prevalence of mastitis. Some of these bacterial isolates can be the real causes of mastitis. However, studies should be conducted to establish causal relationship.

A cross-sectional study was conducted from November 2014 to March 2015 to determine the prevalence, associated risk factors, and effect of bovine mastitis on economic return in dairy farms in Holeta, Ethiopia. It was carried out on 384 dairy cows based on a data collection questionnaire survey, clinical examination, and California Mastitis Test. The overall prevalence of mastitis was 65.1% (n=250); where 25.8% (n=99) and 39.3% (n=151) was clinical and subclinical cases, respectively. The prevalence among successive stages of lactation was 65.6%, 60.3%, and 68.9% in early, mid, and late lactation respectively and it was statistically significant (P&lt;0.05). Mastitis prevalence in first, second, third, fourth, and more than fourth parities was 68.5%, 61.5%, 58.7%, and 71.5%, respectively. The prevalence of mastitis was 78.3%, 60.3% and 68.9% in cows of age greater than 8, 5-8 and less than 5 years respectively. Retrospective data related to treatment costs, discarded milk during the course of treatment, and culled cows due to chronic mastitis in Holeta from 2013 to 2014 was analyzed to estimate the annual economic loss due to mastitis in four dairy farms. The study estimated the annual economic loss of bovine mastitis from 10,044.18 - 15,280.28 birr. Out of this, the total economic loss per cow to treat mastitis was 63.29-139.00 birr and the cost due to discarded milk during the course of treatment was 128.00-535.95 birr per head of a cow. The economic loss due to culled cow and replacement was 9,500-14,666 birr. This study concluded that mastitis is a major health problem of dairy cows in Holeta which undoubtedly affect farm economic return of dairy farms and hence warrants serious attention.

Staphylococcus is increasing in both primiparous and multiparous cows.By comparing the sampling areas we can deduce that the western area of the region can be considered as a risk indicator compared to the northern area while the other two areas are not.On the other hand, the association of the two factors, i.e. stage of lactation and sampling zone, the risk of the western zone becomes insignificant (p=0.07) while the middle of the stage of lactation persists as a non-risk phase.The present study allowed us to evaluate the frequency of subclinical mastitis and to identify the different bacterial strains of staphylococci responsible.In Conclusion, determining the risk factors for the development of Subclinical Mastitis allows us to establish a control program to improve the health of the udder of dairy cows and thus increase milk production.

Mastitis is an inflammation of the mammary gland caused by pathogenic microorganism, occurs in all mammalian species but particularly important in dairy cattle. A cross sectional study design was conducted from June 2015 to September 2015 to screening bovine mastitis in randomly selected dairy farms in and around D/Tsige town. About 384 (118 cross, 153 Exotic, 113 local breed) of lactating cows were included in the study. Prevalence of the clinical mastitis was determined through examination of abnormalities of milk and udder of cows; and California mastitis test to diagnose sub-clinical mastitis. The overall prevalence of clinical mastitis was 9.64% and 9.63% at cow and quarter level respectively. Of the 1536 quarters examined, prevalence of clinical mastitis, sub clinical mastitis and blind quarters (non-functional teats) were found to be 9.63%, 33.85% and 1.2%, respectively. On cow basis, out of 384 lactating cows, 167 (43.49%) cows had abnormalities in their udder, teats and milk as evidence of clinical mastitis. The prevalence of mastitis at cow level was higher in exotic breeds (39.8%) and those were found in late lactation stage (42.2%), parity number was found to be statistically significant (P<0.05). In the present study, there was high prevalence of sub clinical mastitis that result losing of milk production and cause economic lose to the dairy farm. In view of this, the routine test of dairy cows, and preventive and control measures are recommended to reduce the prevalence of clinical and sub clinical mastitis in dairy farms in and around D/Tsige town.

Bovine mastitis continues to be a leading cause of heavy economic losses in the dairy industry and a public health hazard globally. This cross-sectional study investigated the prevalence, etiologies of clinical and subclinical mastitis, and associated predisposing factors in Embu and Kajiado counties in Kenya. A semistructured questionnaire was administered to 154 smallholder dairy farmers to collect data on management practices, animal factors, and disease history. A total of 395 dairy cows were initially screened for subclinical mastitis using the California mastitis test (CMT), and milk samples were aseptically collected. Both CMT positive and CMT negative samples were analyzed using conventional bacteriological isolation and identification procedures. In the present study, the overall prevalence of mastitis based on CMT and clinical examination was 80% (316/395), out of which 6.8% (27/395) was clinical mastitis, while 73.1% (289/395) was subclinical mastitis. Based on culture, the overall prevalence of clinical and subclinical mastitis was 51.6% (815/1580), 74.4% (294/395), and 76.6% (118/154) at the quarter, cow, and farm level, respectively. From the 1574 milk samples analyzed by cultured, 1016 bacteria were yielded. The predominant bacteria were coagulase-negative Staphylococcus (CNS), 42.8% (435/1016), and in decreasing order, Streptococcus species, 22.2% (226/1016), Staphylococcus aureus, 15.7% (160/1016), and Pseudomonas aeruginosa, 5.1% (52/1016), and the least was Enterobacter species, 0.7% (7/1016), while 23.7% of the sample yielded no bacterial growth. Risk factor analysis revealed that milking mastitic cows last (p=0.002), using a clean udder drying towel for each cow (p=0.033) and previous history of mastitis (p=0.046) were significantly associated with presence of mastitis. The current study has shown a relatively high prevalence of subclinical mastitis with CNS as predominant bacteria. Therefore, control measures are urgently warranted. Management factors such as milking mastitic cows last, using a clean towel for udder drying for each cow, and culling mastitic cows should be considered and included in the Kenyan mastitis control programs.

A cross sectional study was conducted from November, 2011 to April, 2012 in Adigrat, Ethiopia, with the objective of assessing the prevalence of bovine mastitis, the risk factors associated with the disease and identifying the bacteria responsible for the disease. A total of 322 cows were selected from 10 small holder dairy farms using simple random sampling method. California Mastitis Test (CMT), clinical examination of udder and teats and bacteriological examination were employed. The overall prevalence of mastitis at a cow level was 64.3% (207/322), from which 15 (31/322) and 85% (176/322) were clinical and subclinical, respectively. The quarter level prevalence of the disease was also 54% (696/1288) from which 20.5 (264/1288) and 33.5% (432/1288) were clinical and subclinical form, respectively. As compared to the others, the right hind quarters were affected with the highest infection rate (63.9%). The left hind quarters were the second with an infection rate of 59.3% followed by right front quarters (52.5%) and left front quarters (40.4%). Among the bacterial causes of bovine mastitis in the study area, Staphylococcus aureus, Echerichia coli and Streptococcus agalactiae were the major isolates with percentages of 51.7, 20.9 and 20.3, respectively. All the potential risk factors considered in this study namely, parity, age, stage of lactation and breed showed significant effects on prevalence of mastitis in the present study. The present study concludes that mastitis was a major health problem of dairy cows in the area. Hence, strategic control measures against the disease and regular surveillance measures are recommended. Key words: Prevalence, bovine mastitis, risk factors, bacteria, Adigrat, Ethiopia.

ABSTRACTBovine mastitis is a widespread and important disease of cows that affects the global production and quality of milk in the dairy industry. A cross‐sectional study conducted from February to August 2022 in the Uba Debretsehay District aimed to determine the prevalence of bovine mastitis, assess the associated risk factors and the antibiotic susceptibility profiles of Staphylococcus aureus isolates from mastitis‐positive cows. A total of 432 cows were screened through clinical examinations and the California mastitis test to determine the occurrence of clinical and sub‐clinical mastitis respectively. A milk sample was collected from mastitis‐positive cows and standard microbiological procedures were used to identify S. aureus. Antimicrobial susceptibility testing was performed using 10 antimicrobials following the Kirby–Bauer disc diffusion method. The overall prevalence of mastitis was 44.2% (191/432; 95% CI = 0.37–0.51) and 41% (702/1728) at the cow and quarter level respectively. The odds for the occurrence of mastitis significantly decreased without tick infestation and or injury (OR = 0.15; 95% CI = 0.07–0.28), and the previous history of mastitis (OR = 0.28; 95% CI = 0.17–0.47). Cows in mid‐stage lactation were 2.13 times more likely to develop mastitis than early‐stage lactating cows. Additionally, cows kept with in larger herds were 1.57 times more prone to mastitis than those on small herd size. Out of the 191 mastitis‐positive milk samples, S. aureus was isolated in 2.6% (5/191) of these samples using the BioLog microbial identification system. S. aureus isolates showed no susceptibility (0%) to penicillin G or tetracycline, but exhibited 100% susceptibility to amoxicillin‐clavulanate, cefoxitin, ciprofloxacin, chloramphenicol, oxacillin, trimethoprim‐sulphamethoxazole, and gentamicin. Mastitis is a severe problem for dairy production in the study area, and the resistance of S. aureus to commonly used antibiotics was observed. Therefore, proactive management strategies including adequate sanitation of the dairy environment, regular screening of animals, and rational use of antibiotic agents were recommended to maintain the productivity and well‐being of dairy cows in the study areas.

A cross-sectional study was conducted from November 2011 to March 2012 on lactating dairy cows to determine the overall prevalence of bovine mastitis, identify associated risk factors and isolate the predominant bacterial agents involved in causing mastitis in and around Wolaita Sodo. A total of 349 lactating cows were examined for mastitis using clinical examination and California mastitis test (CMT). Bacteriological methods were also employed to isolate the causative bacteria. An overall 29.5% (95% CI: 24.7, 34.3) prevalence of mastitis was recorded in the area of which 2.6% (95% CI: 0.9, 4.3) were clinical and 26.9% (95% CI: 22.2, 31.6) subclinical cases. About 90 bacterial isolates belonging to 6 species were identified from mastitic milk samples. The isolates based on their relative frequency of occurrence were Staphylococcus aureus (30%), Streptococcus agalactiae (17.78%), Escherichia coli (17.78%), Staphylococcus epidermids (13.3%), Corynebacterium bovis (12.2%) and Streptococcus dysgalactiae (8.9%). The prevalence of mastitis varied significantly (p&lt;0.05) among breeds, where the highest prevalence was recorded in Jersey (60% (95% CI: 49.3, 70.7)), followed by Holstein-Zebu cross (30.8% (95% CI: 22.9, 38.7)) and Zebu (10.8% (95% CI: 5.6, 16.0)). It was also appreciated that lactation stage and parity significantly (p&lt;0.05) influenced the occurrence of mastitis. Animals at early stage of lactation were severely affected with mastitis than at end and mid lactation stages. The prevalence of mastitis was found to have a direct relation with parity, as the occurrence of mastitis increased with parity. Inadequate sanitation of dairy environment and lack of proper attention to health of mammary gland were important factors (P&lt;0.05) contributing to the prevalence of mastitis. Generally, the study showed that mastitis is an important problem and a serious threat for dairy industry in the study area. Therefore, appropriate control measures targeting the specific causative agents should be in place to reduce the impact of the disease. The farmers should also be aware of the impact of the disease and practice hygienic milking, culling of chronic mastitis carriers and treating of clinically infected cows. Key words: Bacterial isolates, bovine mastitis, lactating cow, prevalence, risk factors, Wolaita Sodo.