Objective—To determine the effects of infiltration of the incision site with bupivacaine hydrochloride as part of a multimodal analgesia protocol (incisional block) on postoperative analgesia and incisional healing.
Procedures—As part of a multimodal analgesic protocol for ovariohysterectomy, dogs received 1 of the following treatments at the incision site: no injection (26 dogs), preincisional infiltration with saline (0.9% NaCl) solution (12 dogs) or bupivacaine (21 dogs), or postincisional infiltration with bupivacaine (33 dogs). Postoperative pain was assessed with the Glasgow pain scale and response to mechanical stimulation with von Frey filaments. Incisions were monitored for signs of inflammation (edema, erythema, and discharge) and complications in wound healing.
Results—There was no difference in pain scores or response to mechanical stimulation over time among treatments. There were no significant differences in incisional edema or discharge among treatments. There was significantly more erythema in dogs that received preincisional infiltration with saline solution at 4 hours after surgery and less erythema in dogs that received postincisional infiltration with bupivacaine at 24 hours after surgery, compared with other treatments. The number of complications for dogs that had preincisional infiltration of bupivacaine was higher than for dogs that had other treatments; complications included excessive inflammation, splenic laceration, and herniation.
Conclusions and Clinical Relevance—No additional analgesic benefit was found in dogs that underwent local bupivacaine infiltration as part of a multimodal analgesic protocol for ovariohysterectomy.
Objective—To characterize the radiosensitivity and capacity for sublethal damage repair (SLDR) of radiation-induced injury in 4 canine osteosarcoma cell lines.
Sample Population—4 canine osteosarcoma cell lines (HMPOS, POS, COS 31, and D17).
Procedures—A clonogenic colony-forming assay was used to evaluate the cell lines' intrinsic radiosensitivities and SLDR capacities. Dose-response curves for the cell lines were generated by fitting the surviving fractions after radiation doses of 0 (control cells), 1, 2, 3, 6, and 9 Gy to a linear quadratic model. To evaluate SLDR, cell lines were exposed to 2 doses of 3 Gy (split-dose experiments) at an interval of 0 (single 6-Gy dose), 2, 4, 6, or 24 hours, after which the surviving fractions were assessed.
Results—Mean surviving fraction did not differ significantly among the 4 cell lines at the radiation doses tested. Mean surviving fraction at 2 Gy was high (0.62), and the α/β ratios (predictor of tissue sensitivity to radiation therapy) for the cell lines were low (mean ratio, 3.47). The split-dose experiments revealed a 2.8- to 3.9-fold increase in cell survival when the radiation doses were applied at an interval of 24 hours, compared with cell survival after radiation doses were applied consecutively (0-hour interval).
Conclusions and Clinical Relevance—Results indicated that these canine osteosarcoma cell lines are fairly radioresistant; α/β ratios were similar to those of nonneoplastic, lateresponding tissues. Future clinical investigations should involve increasing the fraction size in a manner that maximizes tumor killing without adverse effects on the nonneoplastic surrounding tissues.