Abstract
Background:
Postbreeding endometritis in Arabian mares poses a significant reproductive challenge, necessitating proper pathogen identification and antimicrobial susceptibility determination.

Aim:
To investigate the prevalence of intrauterine pathogens and their antimicrobial susceptibility patterns in Arabian mares with postbreeding endometritis.

Methods:
Seventeen Arabian mares were examined clinically and ultrasonographically. Uterine swabs were collected for bacterial isolation and antimicrobial susceptibility testing.

Results:
Clinical endometritis was detected in 29.4% of the mares. Ultrasonographic examination revealed varying degrees of uterine wall thickness: slight (58.82%), moderate (11.76%), and severe (29.41%). Escherichia coli was the predominant pathogen (76.47%), followed by Streptococcus spp. (11.76%), with mixed infections occurring in 11.76% of cases. Both pathogens exhibited high resistance to several antimicrobials but significant susceptibility to β-lactam antibiotics and selected fluoroquinolones.

Conclusion:
Escherichia coli was the primary pathogen associated with postbreeding endometritis in Arabian mares. The high antimicrobial resistance patterns observed emphasize the importance of culture-based treatment selection. β-lactam antibiotics showed promising efficacy against both isolated pathogens.

Key words: Arabian mares, Endometritis, Staphylococcus spp., E. coli, Hira