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Sorafenib is a multi-kinase small molecule inhibitor that targets serine/threonine and tyrosine kinases including the RAF kinase family, VEGFR-2, and PDGFR. The aim of this study was to evaluate the systemic pharmacokinetics of a previously defined tolerable oral dose of sorafenib in tumor-bearing dogs. Six client-owned dogs with a cytologic or histologic diagnosis of cancer were enrolled in this open-label, tolerability study. Dogs were administered sorafenib at an intended dose of 3 mg/kg and serum samples were obtained for analysis of sorafenib serum concentrations at 0, 1, 2, 6, 12, 24, 48, 72, 96, and 168 h post-drug administration. Median time to peak serum sorafenib concentration occurred at 4 h (range 2-12 h) resulting in an average serum concentration of 54.9 ± 33.5 ng/mL (118.2 ± 72.1 nM). Mean sorafenib levels declined by over 70% relative to peak serum concentrations by 24 h in all dogs, suggesting the value of at least twice daily administration. Doses of 3 mg/kg were well-tolerated and no patients in the study experienced adverse events that were attributable to sorafenib. Future trials in dogs with cancer are recommended at this dosing schedule to assess the effect of sorafenib administration on anti-tumor efficacy signals and relevant pharmacodynamic target modulation in vivo ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Cawley, Stewart, Mochel, Veluvolu, Khanna and Fenger.)

Background: Rabacfosadine (RAB), a novel antineoplastic agent conditionally licensed for the treatment of lymphoma in dogs, is efficacious in both naïve and previously treated dogs. Its use in combination with L-asparaginase (L-ASP) has not been studied., Hypothesis/objectives: To evaluate the safety and efficacy of L-ASP given concurrently with RAB in dogs with relapsed multicentric lymphoma., Animals: Fifty-two dogs with relapse of lymphoma after treatment with at least 1 doxorubicin-based chemotherapy protocol., Methods: Open-label, multicenter, prospective single-arm clinical trial. Dogs were treated with RAB at 1.0 mg/kg IV every 21 days for up to a total of 5 doses. L-asparaginase was administered at 400 IU/kg SQ concurrently with the first 2 treatments of RAB., Results: The overall response rate (ORR) for all dogs was 67%, with 19 dogs (41%) achieving a complete response (CR). The median progression-free survival time (MPFS) was 63 days (range 5-428 days). Dogs experiencing a CR as their best response had an MPFS of 144 days (range 44-428 days). Adverse events were similar to previous studies evaluating single agent RAB. Failure to achieve a CR and having previously received L-ASP were negative prognostic factors on multivariate analysis., Conclusions and Clinical Importance: Concurrent RAB/L-ASP appears to be both efficacious and safe for treating relapsed multicentric lymphoma in dogs. Adverse events were most often mild and no unexpected toxicoses were observed., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: Thyroid dysfunction is associated with the use of tyrosine kinase inhibitors (TKI) in people., Hypothesis/objectives: To determine whether dysfunction in the hypothalamic-pituitary-thyroid axis occurs in dogs receiving the TKI, toceranib phosphate., Animals: Forty-three client-owned dogs with cancer., Methods: Prospective, observational study. Concentrations of total thyroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3), and thyroid-stimulating hormone (TSH) were evaluated on day 0, 30, and 90. Dogs also were evaluated for the presence of thyroglobulin autoantibodies., Results: The proportion of dogs with low TT4, low FT4, low TT3, high TSH, or primary hypothyroidism (increased TSH and decreased TT4, FT4 or both) did not change over 90 days. Hormone concentrations remained within laboratory reference intervals, but FT4 (P = 0.0032) and TSH (P < 0.0001) changed over time. Mean FT4 was 1.22 ng/dL (95% confidence interval [CI], 1.10-1.34) on day 0 and 1.00 ng/dL (95% CI, 0.86-1.16) on day 90. Mean TSH was 0.17 ng/mL (95% CI, 0.13-0.23) on day 0 and 0.34 ng/mL (95% CI, 0.24-0.48) on day 90. Furthermore, TT4/TT3 ratio also changed over time (P = 0.0086). Mean TT4/TT3 ratio was 2.57 (95% CI, 2.26-2.88) on day 0 and 2.02 on day 90 (95% CI, 1.61-2.44). Thyroglobulin autoantibodies were not detected in any dog., Conclusions and Clinical Importance: Toceranib phosphate can disrupt the hypothalamic-pituitary-thyroid axis in dogs. Periodic evaluation of TT4, FT4, TT3, and TSH should be carried out in dogs receiving long-term treatment with this medication., (Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

A combination of technical approaches and forensic tools can determine historic causes, timing, and impacts of site contamination.

The regulation of muscarinic acetylcholine receptor (MAChR) subtypes in rat striatum, bladder and heart was examined following a 14-day administration of neuroleptics (clozapine or fluphenazine), anticholinergics (atropine) or a combination of anticholinergics and neuroleptics. Levels of MAChRs were ascertained by the use of immunoprecipitation and radioligand binding. The combined treatment of fluphenazine and atropine produced an increase in all MAChR subtype levels in striatum with m1 receptor levels having the largest increase (270%) from control. A significant increase (105%) was also seen striatal in m2 receptor levels. Residual muscarinic receptor levels, representing the m3 and m4 subtypes, were increased (72%) to a lesser degree above control. Fluphenazine treatment alone increased levels of the m2 MAChR, whereas clozapine administration had no significant effect on levels of any MAChR subtype in this tissue. Administration of the cholinergic antagonist, atropine, showed a significant increase (89%) in the striatal m1 MAChR subtype. Of the MAChRs found in rat bladder and rat heart, the m2 subtype has been shown to be the most abundant. Results from the rat bladders indicated a reduction (50%) in muscarinic antagonist binding that was limited to the fluphenazine treatment group. In heart, atropine treatment alone produce a slight increase (ca. 10%) in receptor binding. No significant effect on muscarinic receptor levels was seen with the other treatment groups. These data demonstrate that there are differences in muscarinic receptor level modulation between central and peripheral tissues.