Evaluation of tarsal injuries in C57BL/6J male mice.

Tarsal joint abnormalities have been observed in aged male mice on a C57BL background. This joint disease consists of calcaneal displacement, inflammation, and proliferation of cartilage and connective tissue, that can progress to ankylosis of the joint. While tarsal pathology has been described previously in C57BL/6N substrains, as well as in STR/ort and B10.BR strain, no current literature describes this disease occurring in C57BL/6J mice. More importantly the behavioral features that may result from such a change to the joint have yet to be evaluated. This condition was observed in older male mice of the C57BL/6J lineage, around the age of 20 weeks or older, at a frequency of 1% of the population. To assess potential phenotypic sequela, this study sought to evaluate body weight, frailty assessment, home cage wheel running, dynamic weight bearing, and mechanical allodynia with and without the presence of pain relief with morphine. Overall mice with tarsal injuries had significantly higher frailty scores (p< 0.05) and weighed less (p<0.01) compared to unaffected mice. Affected mice had greater overall touch sensitivity (p<0.05) and they placed more weight on their forelimbs (p<0.01) compared to their hind limbs. Lastly, when housed with a running wheel, affected mice ran for a shorter length of time (p<0.01) but tended to run a greater distance within the time they did run (p<0.01) compared to unaffected mice. When tested just after being given morphine, the affected mice performed more similarly to unaffected mice, suggesting there is a pain sensation to this disease process. This highlights the importance of further characterizing inbred mouse mutations, as they may impact research programs or specific study goals.

Evaluation of 4 Presurgical Skin Preparation Methods in Mice.

Mice routinely undergo surgical procedures for use in research; however, studies of skin preparation methods to achieve antisepsis are rare. The present study evaluated 4 skin preparation treatments: depilatory agent followed by povidone-iodine and alcohol scrub; depilatory agent followed by povidone-iodine and saline scrub; electric clippers followed by povidone-iodine and alcohol scrub; and electric clippers followed by povidone-iodine and saline scrub. Swabs for bacterial culture were obtained immediately after hair removal and after scrubbing to measure the reduction in bacterial load. Full-thickness incisions were assigned ASEPSIS wound scores and examined histologically on days 0, 1, and 7 after surgery. Neither bacterial load growth nor ASEPSIS wound scores differed among any of the treatments. Histopathology revealed statistically significant but biologically irrelevant differences. Overall all treatment methods achieved acceptable bacterial load reduction and surgical site healing.

Pharmacokinetic Profiles of Nalbuphine after Intraperitoneal and Subcutaneous Administration to C57BL/6 Mice.

Mice undergo a variety of procedures that necessitate the use of analgesic agents. Opioids are often essential to successful pain management plans, but most are controlled substances, and their use requires appropriate federal and state registrations. Nalbuphine is a potentially effective opioid analgesic for mice that is not currently classified as a controlled substance. This compound has received little attention as an analgesic for mice, and standard dosage regimens have not been developed. Here we compared the pharmacokinetic profiles of 10 mg/kg nalbuphine in male C57BL/6 mice subcutaneous or intraperitoneal administration. Blood was collected from 3 mice per treatment at 5, 10, 20, and 30 min and 1, 2, 3, 6, 12, and 24 h after administration. Plasma concentrations were measured, and standard pharmacokinetic parameters were calculated. Profile characteristics for each route of administration were similar, with significant differences in plasma concentration at 5 and 30 min and 1 and 3 h. Nalbuphine was absorbed more quickly when administered subcutaneously (Tmax, 5 min) than intraperitoneally (Tmax, 10 min), whereas the drug's half-life was similar between the intraperitoneal (0.94 h) and subcutaneous (1.12 h) routes. The AUC0-tldc and AUC0-inf were higher but the apparent clearance and apparent volume of distribution were lower after subcutaneous administration compared with intraperitoneal dosing. Plasma concentrations were below the level of detection by 12 h. These results suggest that nalbuphine is absorbed in and eliminated quickly from mice, making it a possible candidate for acute pain management.