The control of experimental canine Pseudomonas aeruginosa infection was optimised via a combined therapy including enrofloxacin against the bacteria and parthenolide (active component of the plant Tanacetum parthenium) for correction of inflammatory reaction. The aim of the present study was to evaluate the effect of this therapy on absolute neutrophil counts (ANC), blood neutrophilic function (phagocytosis, oxidative burst activity), serum naturally occurring antibodies (NAbs), procalcitonin (PCT) in infected animals. Blood samples were collected prior to the infection – hour 0 and post infection hours 4, 24, 48, 72 and day 7 from 25 male dogs, divided into five equal groups. Group C included healthy dogs (negative control). Dogs from Group 0 were injected subcutaneously with P. aeruginosa bacterial culture (1×108 CFU/mL) and untreated (positive control). The infected dogs from group I were treated s.c. with enrofloxacin on post infection hour 48 at 5 mg/kg. Dogs from Group II were treated beginning from the 4th hour post infection with standardized feverfew extract – 90 mg, 0.7% parthenolidegiven orally at 2 capsules daily for 6 days. Group III included