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  • Author or Editor: Michael D. Lucroy x
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Abstract

Objective—To determine whether transitional cell carcinoma (TCC) cells incubated in media containing 5-aminolevulinic acid (ALA) would produce sufficient protoporphyrin IX (PpIX) to cause lethal phototoxic effects when exposed to 635-nm light.

Sample Population—Canine TCC cells (K9TCC).

Procedure—Cultured K9TCC cells were exposed to graded doses of ALA, and PpIX concentrations were determined. Cells then were exposed to various doses of 635-nm light from a diode laser, and cell viability was assayed.

Results—Production of PpIX was dependent on time and dose of ALA. The K9TCC cells incubated with ALA produced sufficient PpIX to cause lethal phototoxic effects when exposed to 635-nm light. Phototoxic effects were dependent on time and dose of ALA. Increasing laser power density and energy density decreased cell survival.

Conclusions and Clinical Relevance—ALA is an effective photosensitizer for in vitro photodynamic treatment of K9TCC cells. Further studies are warranted to assess the safety and efficacy of ALA as a photosensitizer for use in treating dogs with TCC.

Impact for Human Medicine—On the basis of this study, dogs with TCC may be useful in the development of protocols for ALA-based photodynamic therapy of humans affected with muscle-invasive bladder cancer. (Am J Vet Res 2003;64:131–136)

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in American Journal of Veterinary Research

Abstract

Objective—To determine whether the presence of anemia (Hct ≤ 37%) at the time of diagnosis of lymphoma is a negative prognostic indicator for response to treatment and survival time in dogs that are undergoing chemotherapy.

Design—Retrospective case series.

Animals—96 dogs with lymphoma that were receiving chemotherapy.

Procedures—Information regarding signalment, initial hematologic data, chemotherapy protocol, clinical response, and date of death was retrospectively collected from medical records of dogs with lymphoma. Univariate, multivariate, and survival analyses were performed to determine the effect of anemia on initial response to chemotherapy and on survival time.

Results—Overall, dogs without anemia (n = 56) were 4 times as likely as dogs with anemia (40) to have a complete response following chemotherapy. Anemic dogs had a significantly shorter median survival time (139 days), compared with survival time of nonanemic dogs (315 days). Subset analysis of dogs with multicentric lymphoma (matched for clinical stage and chemotherapy protocol) revealed that the dogs with anemia (n = 24) had a significantly shorter median survival time (101 days), compared with survival time of dogs without anemia (24; 284 days). Other variables were not associated with survival time.

Conclusions and Clinical Relevance—These findings suggested that anemia is a negative prognostic factor for dogs with lymphoma that are undergoing chemotherapy. Further investigation will be necessary to determine the impact of resolution of anemia on clinical outcome in dogs with lymphoma.

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in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objective—To describe diseases, prognosis, and clinical outcomes associated with extreme neutrophilic leukocytosis in cats.

Design—Retrospective study.

Animals—104 cats with extreme neutrophilic leukocytosis.

Procedure—Medical records from 1991 to 1999 were examined to identify cats that had ≥ 50,000 WBC/µl with ≥ 50% neutrophils. Signalment, absolute and differential WBC counts, rectal temperature, clinical or pathologic diagnosis, duration and cost of hospitalization, and survival time were reviewed.

Results—Mean age of cats was 8.3 years, mean WBC count was 73,055 cells/µl, and mean absolute neutrophil count was 59,046 cells/µl. Mean duration of hospitalization was 5.9 days, and mean cost of hospitalization was $2,010. Twenty-nine (28%) cats were febrile, and 63 (61%) cats died. Overall median survival time was 30 days. Cats with neoplasia were nearly 14 times as likely to die unexpectedly as cats with other diseases.

Conclusions and Clinical Relevance—Extreme neutrophilic leukocytosis was associated with a high mortality rate. The prognostic importance of extreme neutrophilic leukocytosis should not be overlooked. Cats and dogs have similar diseases, mortality rates, and treatment costs associated with extreme neutrophilic leukocytosis. (J Am Vet Med Assoc 2001;218:736–739)

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in Journal of the American Veterinary Medical Association

Abstract

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.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether there was a decline in the percentage of dogs undergoing necropsies and whether there was substantial agreement or disagreement between clinical and pathologic diagnoses.

Design—Retrospective study.

Animals—623 dogs.

Procedure—Medical records of hospitalized dogs that died or were euthanatized and necropsied at a veterinary teaching hospital in 1989 and 1999 were reviewed. Clinical and pathologic diagnoses were recorded and compared.

Results—There was a significant decline in the necropsy rate of hospitalized dogs that died or were euthanatized in 1999, compared with 1989. In both 1989 and 1999, there was disagreement between the clinical and pathologic diagnoses in approximately a third of the cases.

Conclusions and Clinical Relevance—Despite improved diagnostic methods, the accuracy of diagnosis did not improve significantly in 1999, compared with 1989. Necropsy is the best method to assess overall diagnostic accuracy. Increased availability of teaching funds may promote efforts to have necropsies performed in veterinary teaching hospitals. ( J Am Vet Med Assoc 2004;224:403–406)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the antitumor activity and toxic effects of a conservative dose of cisplatin administered in combination with piroxicam to dogs with transitional cell carcinoma (TCC) of the urinary bladder.

Design—Clinical trial (nonrandomized, noncontrolled).

Animals—14 client-owned dogs with histologically confirmed TCC of the urinary bladder.

Procedures—Each dog was treated with cisplatin (50 mg/m2, IV, q 21 d [reduced to 40 mg/m2, IV, q 21 d because of toxic effects]) and piroxicam (0.3 mg/kg [0.14 mg/lb], PO, q 24 h). A CBC, serum biochemical analyses, and urinalysis were performed prior to each cisplatin treatment. Tumor staging (determined from thoracic and abdominal radiographic and urinary bladder ultrasonographic findings) was performed before treatment and at 6-week intervals during treatment.

Results—5 dogs received only 1 dose of cisplatin because of the rapid progression of disease (n = 2) or toxic effects (3). With regard to the neoplastic disease among the other 9 dogs, 1 had partial remission, 5 had stable disease, and 3 had progressive disease after 6 weeks of treatment. Median progression-free interval was 78 days (range, 20 to 112 days). Median survival time was 307 days (range, 29 to 929 days). Moderate to severe renal toxicosis and moderate to severe gastrointestinal toxicosis developed in 5 and 8 dogs, respectively.

Conclusions and Clinical Relevance—Because of minimal efficacy and associated renal and gastrointestinal toxicosis, administration of cisplatin (40 to 50 mg/m2) with piroxicam cannot be recommended for treatment of dogs with TCC of the urinary bladder.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare histologic artifacts caused by carbon dioxide (CO2) or 810-nm diode surgical lasers used to obtain small biopsy specimens of skin from healthy dogs.

Design—Prospective study.

Animals—4 dogs.

Procedure—21 skin biopsy specimens were collected from each dog. Three biopsy specimens were obtained with a CO2 or an 810-nm diode laser at 3 operating settings each, and 3 biopsy specimens were obtained with a 6-mm biopsy punch instrument (controls). After processing, biopsy specimens were examined for artifacts related to laser-tissue interactions. Microscopically visible char was measured from the lateral edge of each specimen obtained with a laser.

Results—There were no significant differences among mean char distances in biopsy specimens obtained with the CO2 laser at various settings. Mean char distance was significantly greater in all skin biopsy specimens obtained with the diode laser, compared with those obtained with the CO2 laser. Mean char distance was significantly greater in biopsy specimens obtained with the 810-nm diode laser at high power, compared with biopsy specimens obtained with the 810-nm diode laser at low power.

Conclusions and Clinical Relevance—Results indicated that the CO2 laser caused less thermal injury at margins of skin biopsy specimens; therefore, if a surgical laser is used for removal of cutaneous masses or to obtain skin biopsy specimens, use of the CO2 laser is recommended. Veterinarians performing a biopsy by using a surgical laser should be aware that laser-induced artifacts may render small biopsy specimens useless for providing accurate histologic diagnosis. (J Am Vet Med Assoc 2004;225:1562–1566)

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in Journal of the American Veterinary Medical Association