David Prandi

Comparison of subcutaneous and transdermal administration of buprenorphine for pre-emptive analgesia in dogs undergoing elective ovariohysterectomy.

The clinical efficacy of a 70 microg/h transdermal buprenorphine patch and of 20 microg/kg of buprenorphine administered subcutaneously (SC) for the relief of post-operative pain was determined in 24 healthy female dogs undergoing elective ovariohysterectomy (OHE). Dogs were randomly assigned to three groups: (1) a control group that received no analgesics, (2) a BSC group that received buprenorphine SC (20 microg/kg), and (3) a BP group that received buprenorphine by a 70 microg/h transdermal patch. Dogs were scored for signs of pain at 0, 2, 4, 6, 8, 10, 14, 20, 26, 32 and 38 h after extubation using the Numerical Rating Scale (NRS) and a modified University of Melbourne Pain Scale (UMPS). Mean NRS and UMPS scores for dogs in the BSC group (2.56 ± 0.23 and 3.05 ± 0.27, respectively) and the BP group (2.02 ± 0.24 and 2.67 ± 0.23, respectively) were significantly lower (P<0.05) compared with dogs in the control group (5.42 ± 0.38 and 7.89 ± 0.44, respectively), whereas differences between the two buprenorphine treatment groups were not significant. The results indicated that the analgesia produced by the 70 microg/h patch was similar to that induced by SC administration of 20 microg/kg of buprenorphine in dogs undergoing OHE, suggesting that the transdermal buprenorphine patch may be a useful alternative for pain management in dogs.

Migration pathways of hypodermically injected technetium-99m in dogs.

Hypodermic injection of technetium-99m (99mTC-pertechnetate) at points of low electrical resistance give rise to rapid, longitudinal, and progressive diffusion of the radioactive tracer. We assessed the effect of cutaneous incisions that did not intersect the migration trajectory of 99mTc-pertechnetate and the re-establishment of pathways after the suture of incisions that intersected the migration trajectory. Linear and rapid migration of 99mTc-pertechnetate was not altered or prevented by incisions that did not intersect the migration pathway. Different patterns of 99mTc-pertechnetate spread were found when incisions intersected the radioactive pathways until restoration of the normal migration pathway observed in undamaged skin occurred. In all experiments in which migration of 99mTc-pertechnetate was observed, lavage of surgical wounds was followed by disappearance of the 99mTc-pertechnetate migration observed around the suture. Linear migration of the tracer was not observed when the incision was left uncovered, filled with petroleum jelly, or with a solid silicone sheet, but it was seen when non-sutured incisions were filled with transonic or silicone gel or covered with a solid silicone sheet parallel to the cutaneous plane. These data show that after a cutaneous incision that intersected the diffusion trajectory of the radioactive tracer, linear migration of 99mTc-pertechnetate hypodermically injected at points of low electrical resistance was restored before healing of the cutaneous incision and was independent of incisions made on the skin not overlying the radioactive pathway. A mechanism similar to that of capillary electrophoresis is suggested to explain the hypodermic diffusion of inert particles through specific and constant linear pathways.

Kinetics of hypodermically injected technetium-99m and correlation with cutaneous structures: an experimental study in dogs

We investigated the involvement of cutaneous structures in specific linear migration pathways of technetium-99m pertechnetate hypodermically injected at points of low electrical resistance in the metacarpus of male beagles. Skin-deep incisions were made in the front or back legs on either the same side as the 99mTc injection or on the opposite side. Incisions in the back legs did not affect the migration pattern. Incisions in the front legs before the injection of 99mTc prevented tracer migration. After the injection of 99mTc, incisions in the front contralateral leg caused sudden cessation of the migration, while incisions in the ipsilateral leg caused immediate disappearance of the pathway previously observed. Radioactivity was not detected in flaps obtained from the skin overlying the migration pathway or from the corresponding area of the contralateral leg. In conclusion, the specific linear migration pathways of 99mTc hypodermically injected at points of low electrical resistance cannot be explained by any known biological function. Although the migration of 99mTc does not seem to be strongly linked to any cutaneous structure, the skin overlying the radioactive pathway and the corresponding area of the contralateral leg must be intact if tracer migration is to take place.