Effects of doxycycline, amoxicillin, cephalexin, and enrofloxacin on hemostasis in healthy dogs.
OBJECTIVE
To determine the effects of enteral administration of doxycycline, amoxicillin, cephalexin, and enrofloxacin at therapeutic dosages for a typical duration on hemostatic variables in healthy dogs.


METHODS
14 Beagles.


METHODS
Doxycycline (10 mg/kg, PO, q 12 h), amoxicillin (30 mg/kg, PO, q 12 h), cephalexin (30 mg/kg, PO, q 12 h), and enrofloxacin (20 mg/kg, PO, q 24 h) were administered in random order to 10 healthy dogs at standard therapeutic dosages for 7 days, with a 7-day washout period between subsequent antimicrobials. In addition, 4 Beagles served as control dogs. Variables were evaluated before and after antimicrobial administration; they included platelet count, Hct, 1-stage prothrombin time (PT), activated partial thromboplastin time (PTT), fibrinogen concentration, and platelet function. Platelet function was assessed via buccal mucosal bleeding time, aggregation, and a platelet-function analyzer.


RESULTS
Administration of all antimicrobials caused a slight prolongation of 1-stage PT and activated PTT and slight decrease in fibrinogen concentration. Cephalexin caused a significant increase in 1-stage PT and activated PTT, amoxicillin caused a significant increase in activated PTT, and enrofloxacin caused a significant decrease in fibrinogen concentration. Platelet count or function did not differ significantly after administration of any antimicrobial.


CONCLUSIONS
Oral administration of commonly used antimicrobials in healthy dogs resulted in minor secondary hemostatic abnormalities, with no change in platelet count or function. Although these changes were clinically irrelevant in healthy dogs, additional studies of the effects of antimicrobial administration on hemostasis in animals with underlying disease processes are warranted.
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
Jinelle A
JA
Webb
Dana G
DG
Allen
Anthony C G
AC
Abrams-Ogg
Patricia A
PA
Gentry
D000658:Amoxicillin / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001760:Bleeding Time; D002506:Cephalexin / Q000008:administration & dosage / Q000494:pharmacology*; D004285:Dogs / Q000097:blood*; D004318:Doxycycline / Q000008:administration & dosage / Q000494:pharmacology*; D000077422:Enrofloxacin; D005260:Female; D024841:Fluoroquinolones / Q000008:administration & dosage / Q000494:pharmacology*; D006487:Hemostasis / Q000187:drug effects*; D008297:Male; D010314:Partial Thromboplastin Time; D010976:Platelet Count; D010979:Platelet Function Tests; D011517:Prothrombin Time; D012016:Reference Values
D024841:Fluoroquinolones; D000077422:Enrofloxacin; D000658:Amoxicillin; D004318:Doxycycline; D002506:Cephalexin