The effect of four anesthetic protocols on the spleen in dogs

Splenic enlargement following administration of barbiturates has been well described in dogs; other agents have not been investigated. This study aimed to compare the effects of four anesthetic protocols on splenic size.
Twenty-four fasted Beagle dogs scheduled for laparotomy were allocated to one of the four groups. Group 1: acepromazine and butorphanol followed by induction with thiopental; Group 2: acepromazine and butorphanol followed by induction with propofol; Group 3: medetomidine and butorphanol followed by induction with propofol; Group 4: medetomidine and butorphanol followed by induction with ketamine and diazepam. Anesthesia was maintained with halothane in oxygen, intravenous fluids were administered. Splenic length, width and height were measured once when the abdomen was opened and again just prior to closure. Spleens were also traced, the image was digitized, and the area was calculated. PCV and total solids were measured before and after pre-medication, after induction, and each time the spleen was measured. Data were analyzed using a Repeated Measures anova with splenic variables indexed by body surface area and dose of induction agent as a covariate.
Area and width of the spleens were less in the dogs of Groups 2 and 3 than in those of the other groups. Splenic area and length did not change significantly during surgery. Dosage of propofol was not significantly different between Groups 2 and 3. Baseline PCV was not significantly different among groups and decreased significantly in all dogs, but at different times. In Groups 1 and 2, the decrease occurred after pre-medication, in Group 3 at induction, and in Group 4 during surgery. A significant decrease in TS occurred in all groups during surgery.
We concluded that the use of propofol resulted in smaller spleen size during surgery than that following the use of thiopental. Multiple factors influenced the PCV.