A case control study was conducted to ascertain the prevalence of clinical disease and clinical disorders of sick pet dogs presented to the City Veterinary Hospital Kathmandu Valley Nepal for a period of one year from July 2020 to June 2021. A total 1409 clinically ill pet dogs were examined and recorded the disease and disorders on the basis of age, season and breeds of dogs. Among diseases and disorders the highest prevalence (26.54%), was significantly (p <0.01) seen by viral disease followed by digestive disorders (10.14%), ear and eye disease (8.72%), respiratory disorders (7.73%), fungal disease (7.16%), protozoan disorders (6.52%), urinary disorders (5.53%), metabolic and nutritional disease (5.39%), genital disease (5.03%), skin disorders (4.54%), helminthiasis (3.97%), external parasite (3.12%), poisoning (3.12%), and lowest (2.41%) by edema. It is observed that the prevalence of diseases and disorders was significantly (p <0.01) higher above 36 months of age group and moderate in 7-36 months’ age and lowest in 0 to 6-month age groups. According to season the highest prevalence (29.59%) was seen in winter season (December-February) followed by 25.90% in summer (March-May), 24.27% in autumn and lowest 20.22 % in rainy season and it was statistically significant (p <0.01). According to breed the prevalence was significantly higher 34.56% in local dogs followed by 14.05% in German shepherd dogs, 10.14% in Labrador breed, 7.94% in pug, 7.59% in Golden Retriever breed, 6.03 % in lhasa Apso breed, 5.89% in Doberman breed, 4.61% in Spitz breed, 3.97% in Boxer breed, 3.26% in Beagle breed and lowest 1.92% seen in Spaniel breed. The present study demonstrated the excellent efficacy of Amoxicillin @ 20mg/kg body weight against secondary bacterial infection of canine parvo virus infection reduced the clinical signs of CPVI within 6.0±0.32 days than Ceftriaxone @ 25 mg/kg body weight and Enrofloxacin @ 8mg/kg body weight that took recovery period of 7.4±0.25and 7.9±0.37 days respectively but it was not statistically significant and present study demonstrated the excellent efficacy of Doxycycline @ 10mg/kg body weight against Ehrlichiosis reduced the clinical signs within 5.0±0.32 days than Rifampicin @ 20 mg/kg body weight orally that took recovery period of 8.0±0.25 days In conclusion it was observed that the age, seasons and breed has effect on disease and disease conditions of pet dogs and commercial drug was found effective to control infections and healing of CPVI lesion.