PREDNISOLONE AT ANTIINFLAMMATORY OR IMMUNOSUPPRESSIVE DOSAGES IN CONJUNCTION WITH DOXYCYCLINE DOES NOT POTENTIATE THE SEVERITY OF RICKETTSIA-RICKETTSII INFECTION IN DOGS

Dogs were experimentally inoculated with Rickettsia rickettsii to dete rmine if anti-inflammatory or immuno-suppressive dosages of prednisolo ne, when administered in conjunction with an antirickettsial antibioti c (doxycycline), induce therapeutically relevant pathophysiologic cons equences that ultimately influence disease outcome, Although the durat ion of rickettsemia was prolonged in dogs receiving immunosuppressive, but not anti-inflammatory, corticosteroids, concurrent administration of doxycycline and corticosteroids conferred no other detected detrim ental effects, Treatment with doxycycline or doxycycline in conjunctio n with prednisolone resulted in decreased R. rickettsii-specific antib ody titers; however, examination of appropriately timed acute-and conv alescent-phase serum samples would have facilitated an accurate diagno sis of Rocky Mountain spotted fever (RMSF) in all 16 dogs. We conclude that the concurrent use of anti-inflammatory or immunosuppressive dos es of prednisolone in conjunction with doxycycline, early in the cours e of experimental RMSF, confers no clinically relevant detrimental eff ects and that additional studies might be indicated to detect possible beneficial effects in cases of severe or potentially fulminant RMSF, However, because the illness induced in these dogs was of mild to mode rate severity, the results of this study should definitely not be cons trued as supporting the safety or efficacy of prednisolone for treatme nt of severe canine or human RMSF.