T. Schermerhorn et al., WHOLE-BLOOD PLATELET-AGGREGATION, BUCCAL MUCOSA BLEEDING-TIME, AND SERUM CEPHALOTHIN CONCENTRATION IN DOGS RECEIVING A PRESURGICAL ANTIBIOTIC PROTOCOL, American journal of veterinary research, 55(11), 1994, pp. 1602-1607
Whole-blood platelet aggregation (using the impedance method) and aden
osine triphosphate (ATP) release, buccal mucosal bleeding time (BT), a
nd serum cephalothin concentration were measured in 21 adult female Be
agles before (PRE) and 1 hour (1 HR) after IV administration of cephal
othin (22 mg/kg). A second injection of cephalothin (22 mg/kg) was giv
en 3 hours after the first, and blood samples were obtained 1 hour (4
HR, 4 hours after the first injection) and 3 hours (6 HR, 6 hours afte
r the first injection) after the second injection. Samples of jugular
blood were obtained from each dog, using citrate as an anticoagulant.
A platelet count was obtained for each sample. Platelet aggregation an
d Am released from the aggregating platelets were measured within 1 ho
ur of sample collection, using a whole-blood aggregometer. Adenosine d
iphosphate (ADP) and collagen were used as aggregating agents. Aggrega
tion was measured over 6 minutes for each aggregating agent; Am releas
e in response to collagen, but not to ADP, was measured over the same
period. For 1 HR samples, there was a significant (P < 0.01) reduction
from PRE values in the ability of platelets to aggregate in response
to ADP. Bleeding time was determined, using a published procedure, wit
h each dog as its own control. Bleeding time during the same period wa
s found to be significantly increased over PRE values for 1 HR (P < 0.
01) and 6 HR (P < 0.02) samples. There was no significant difference b
etween BT for 1 HR and 4 HR samples. Median serum cephalothin concentr
ations in PRE, 1 HR, 4 HR, and 6 HR samples did not correlate signific
antly to platelet aggregation, An release, platelet count, or BT at an
y time during the study. Because serum cephalothin concentration was s
o low, and because there are few reports of the kinetics of cephalothi
n after IV administration, serum cephalothin was measured in 2 dogs ov
er 2 hours after single IV administration of cephalothin. Values reach
ed a peak at 2 minutes after drug administration, then decreased rapid
ly over 10 to 15 minutes, and were low by 2 hours.