Periodontal disease is a multifactorial chronic inflammatory disease that can have a significant impacts on a pet's health. Home oral hygiene and diet have been shown to have an impact on periodontal health. The present study aimed to evaluate the effect of periodontitis on the development of oxidative stress and the disturbance of some reproductive hormones in male cats. The present study was carried out on twenty male cats aged from 7 months to 2.5 years, 10 healthy and 10 suffering from oral inflammation, from some veterinary clinics in Cairo. They were divided into 3 groups. group1 apparently healthy, group2 chronic oral inflammation gp before treatment, group3 the same oral inflammated cats treated by clindamycin for 7 days (clindamycin treated gp). Our results displayed a significant increase in serum malondialdehyde, glucose, estradiol, liver, kidney, and heart biomarkers; conversely, a significant decrease in serum total protein, albumin, total beta, albumin: globulin ratio, and testosterone were observed in oral inflammation-non-treated cats as compared with normal healthy cats. The results of the present study suggested that oral inflammation in cats is associated with oxidative stress. Furthermore, our study showed that oral inflammation diseases could not only cause oral local diseases but could also induce systemic diseases through the effect of oxidative stress.