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  • Author or Editor: Antonella Borgatti x
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Objective—To determine the threshold for acute toxicosis of parenterally administered zinc phthalocyanine tetrasulfonate (ZnPcS4), a candidate second-generation photosensitizer, in mice and evaluate the compound's safety in a phase I clinical trial of ZnPcS4-based photodynamic therapy (PDT) in pet dogs with naturally occurring tumors.

Animals—Male Swiss-Webster mice and client-owned dogs with naturally occurring neoplasms.

Procedures—For the study of acute toxicosis, mice were given graded doses of ZnPcS4. To determine safety, a rapid-titration phase I clinical trial of ZnPcS4-based PDT in tumor-bearing dogs was conducted.

Results—In mice, administration of ≥ 100 mg of ZnPcS4/kg resulted in renal tubular necrosis 24 hours after IP injection. In tumor-bearing dogs, ZnPcS4 doses ≤ 4 mg/kg induced no signs of toxicosis and resulted in partial to complete tumor responses in 10 of 12 dogs 4 weeks after PDT. Tumor remission was observed with ZnPcS4 doses as low as 0.25 mg/kg.

Conclusions and Clinical Relevance—A conservative starting dose of ZnPcS4 was arrived at on the basis of mouse toxicosis findings. Zinc phthalocyanine tetrasulfonate–based PDT was tolerated well by all dogs and warrants further study. The identification of the maximum tolerated dose through traditional phase I clinical trials may be unnecessary for evaluating novel PDT protocols.

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in American Journal of Veterinary Research



To identify physical examination and perioperative CBC variables in dogs with splenic hemangiosarcoma (HSA) that could aid in predicting progression-free interval (PFI) and overall survival time (OST) in affected dogs.


70 client-owned dogs with splenic HSA treated with splenectomy and chemotherapy between September 2004 and October 2016.


A retrospective search of the University of Minnesota Veterinary Medical Center medical records database was performed to identify dogs with splenic HSA treated with splenectomy and with evidence in the medical records of intent to treat with chemotherapy. Data collection included dog signalment and body surface area, results from CBCs performed within 6 days before to 2 days after splenectomy, whether dogs had hemoabdomen or received transfusions, and tumor stage. Hematocrit, WBC count, and platelet count were treated as categorical variables (divided into terciles: above, within, or below reference limits) because of variation among reference intervals for the numerous analyzers used. Associations between variables and PFI or OST were investigated with Cox regression analyses, and hazard ratios (HRs) for a shorter PFI or OST were reported. Population Pearson correlation coefficient (ρ) analysis was performed to identify potential associations between variables of interest.


Stage 3 HSA was identified as a negative prognostic indicator of PFI (HR, 6.6) and OST (HR, 4.5). Perioperative thrombocytopenia was similarly associated with shorter PFI (HR, 2.2) and OST (HR, 2.0). Results for Hct correlated (ρ = 0.58) with those for platelet count, and although our findings did not indicate a notable association between anemia and shorter PFI, such could not be ruled out.


The prognostic value of thrombocytopenia warrants further substantiation to understand causal and mechanistic connections, and the presence of thrombocytopenia ultimately may prove valuable in guiding treatment recommendations for dogs with splenic HSA.

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in Journal of the American Veterinary Medical Association