Abstract
There is limited epidemiological knowledge on udder health in Upper Egypt dairy cattle and buffaloe that would aid in a pro-active approach towards mastitis prevention. The study objectives were to investigate the prevalence rate of clinical mastitis for dairy bovine animals ownered by small holders, located at all Upper Egypt Governorates. Also detection of the most common mastitis pathogens that affect the level of milk production and to test whether there is a correlation between the location, animal species, and seasons of breeding with prevalence of clinical mastitis. Also to detecte the drugs of choice for the treatement of bovine clinical mastitis in different Governorates of Upper Egypt .A total of 345 lactating cattle cows and 111 lactating buffaloe cows, suffered from clinical mastitis, at different lactation seasons from small holders of six Governorates of Upper Egypt, were tested by general bacteriological investigations, during three cycling visits for the presence of clinical mastitis. The prevalence of clinical mastitis ranged from 7.5 % to 29.3 % for cattle cows and from 13.5 % to 27.9 % for buffaloe cows based on the Governorate location and atmospheric nature. Milk samples from clinical mastitic cattle and buffaloe cows were examined bacteriologically; 95.4% and 92.8 were culturally positive, meanwhile the culturally negative samples were 4.6% and 7.2% for cattle and buffaloe cows' respectivelly. As a mean of infections in all Upper Egypt Governorates ,Staphylococcus aureus (S. aureus) was the predominant mastitis pathogen followed by Escherichia coli ( E.coli ) ,Other strept.and Coagulase negative Staphylococcus ( CNS ) 37.7%, 26.7%, 18.0% and 13.0% respectively for cattle clinical mastitis .On the other hand ,also S.aureus was the main cause of infection for buffaloe cows clinical mastitis (46.8%) followed by CNS, E.coli and Other strept. infections ( 16.2%,15.3% and 14.4% respectively ) .Animal species,Regions and seasons play an important significant role in bovine clinical mastitis affecting causes and treatement in Upper Egypt We concluted from the results of sensitivity test for clinically mastitic milk samples that Amoxicillin/clavulinic acid, Cefiquinom, Ciprofloxacin and Florofenicol were the top antibiotics for the treatement of all pathogens isolated from cattle cows in all Governorates of Upper Egypt.Meanwhile Florofenicol, Gentamycin, Neomycin, Tetracyclin, Penecillin and Ampicillin were the most important antibiotics used for the treatement of clinically mastitic buffaloe cows.These findings provide information about nature of clinical mastitis for improved treatment efficacy and pro-active approaches towards mastitis prevention in Upper Egypt . Sampling of clinical mastitic milk in different seasons would provide complete understanding of udder health throughout the year.

Key words: Key words: clinical mastitis, intramammary infection, Dairy cows , Epidemiology of udder infection.