Ifyourdoghasaconcurrentbacterialorviralinfection,oraparasiticinfestation,yourveterinarianwillneedtotreatitfirstwithanappropriateantibioticoranti-parasiticmedicines.

Please segment the words.
If your dog has a concurrent bacterial or viral infection, or a parasitic infestation, your veterinarian will need to treat it first with an appropriate antibiotic or anti-parasitic medicines.