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  • Author or Editor: Satoru Matsunaga x
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in Journal of the American Veterinary Medical Association



To evaluate cardiopulmonary effects of sevoflurane (Sevo), compared with halothane (Hal), enflurane (Enf), and isoflurane (Iso).


24 healthy Beagles, randomly assigned to 4 groups of 6 dogs each.


Dogs under spontaneous ventilation were anesthetized with Sevo, Hal, Enf, or Iso. After minimum alveolar concentration (MAC) of each anesthetic was determined, anesthesia was maintained at light (1 MAC), moderate surgical (1.5 MAC), and deep (2 MAC), stages and cardiopulmonary variables at conscious state (baseline) and each anesthesia stage were measured.


In dogs of the Sevo group, heart rate increased significantly from the baseline value at all anesthesia stages. Systemic vascular resistance during Sevo anesthesia decreased gradually with increasing anesthesia stage, which was accompanied by dose-dependent decreases in systolic, mean, and diastolic arterial blood pressures. At 1.5 and 2 MAC Sevo, stroke index decreased slightly but significantly from the baseline value; however, cardiac index was unchanged because of the significant increase in heart rate. Respiratory rate decreased significantly at 2 MAC from that at 1 MAC Sevo. Tidal volume and dead space-to-tidal volume ratio were unchanged at all anesthesia stages of Sevo, resulting in significantly decreased expired and alveolar ventilation at 2 MAC, compared with values at 1 and 1.5 MAC Sevo. Pa CO 2 increased and pHa decreased significantly, depending on anesthesia stage; Pa O 2 increased significantly from baseline values, and remained constant because of inhalation of 100% O2.


Cardiovascular effects of Sevo were greater than those of Hal, similar to those of Iso, and less than those of Enf. Respiratory effects of Sevo were similar to those of Iso at all anesthesia stages, greater than those of Hal at 2 MAC, and less than those of Enf at 1.5 and 2 MAC. Up to the moderate surgical anesthesia stage, Sevo can be used safely in dogs undergoing spontaneous ventilation. (Am J Vet Res 1997;58:885–890)

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in American Journal of Veterinary Research


Objective—To determine whether magnetic resonance imaging findings in dogs with paraplegia caused by thoracolumbar intervertebral disk extrusion were predictive of clinical outcome.

Design—Retrospective case series.

Animals—77 dogs.

Procedure—Medical records and magnetic resonance images were reviewed; clinical outcome was classified as successful (regained ability to walk with no more than mild neurologic deficits) or unsuccessful (severe neurologic deficits persisted). The prognostic value of magnetic resonance imaging was compared with prognostic value of deep pain perception, duration of clinical signs, and rate of onset of clinical signs.

Result—33 (43%) dogs had areas of hyperintensity of the spinal cord greater than or equal to the length of the L2 vertebral body on T2-weighted magnetic resonance images. All 44 dogs without areas of hyperintensity on T2-weighted images had a successful outcome, but only 18 of the 33 (55%) dogs with an area of hyperintensity did. Only 5 of 16 dogs with an area of hyperintensity that had also lost deep pain perception had a successful outcome. The odds ratio for an unsuccessful outcome for a dog with an area of hyperintensity (29.87) was higher than the odds ratio for a dog that had lost deep pain perception (5.24). Duration and rate of onset of clinical signs were not associated with clinical outcome.

Conclusions and Clinical Relevance—Findings suggest that results of magnetic resonance imaging can be used to predict clinical outcome in dogs with paraplegia caused by intervertebral disk extrusion. (J Am Vet Med Assoc 2005;227:1454–1460)

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in Journal of the American Veterinary Medical Association


Objective—To determine differentiation and growth inhibition effects of retinoids on canine osteosarcoma cells.

Sample Population—3 osteosarcoma cell lines established from osteosarcomas in dogs.

Procedure—Osteosarcoma cells were incubated with various concentrations of all-trans-retinoic acid and 9-cis-retinoic acid or control medium, counted daily for 10 days, and evaluated for morphologic changes. Synthesis of DNA was measured by use of a cell proliferation ELISA. To analyze effect of retinoids on colony formation on plastic dishes, cells were cultured for 14 days, fixed, and stained; number of colonies was counted.

Results—In a dose-dependent manner, both retinoids induced morphologic differentiation and growth inhibition in the 3 osteosarcoma cell lines and inhibited each cell's ability to form anchorage-dependent colonies.

Conclusion and Clinical Relevance—Retinoids induced differentiation of osteosarcoma cells of dogs, resulting in altered expression of their malignant phenotype. Induction of differentiation by retinoids may have potential as an adjunctive treatment for osteosarcoma in dogs. (Am J Vet Res 2000;61:69–73)

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in American Journal of Veterinary Research


Objective—To determine effects of all-trans and 9-cis retinoic acid (RA) on tumor growth and metastatic ability of canine osteosarcoma cells transplanted into athymic (nude) mice.

Animals—Forty-five 5-week-old female BALB/c nude mice.

Procedure—1 × 107 POS osteosarcoma cells were transplanted subcutaneously into the intrascapular region of mice. All-trans RA (3 or 30 µg/kg of body weight in 0.1 ml of sesame oil), 9-cis RA (3 or 30 mg/kg in 0.1 ml of sesame oil), or sesame oil (0.1 ml; control treatment) were administered intragastrically 5 d/wk for 4 weeks beginning 3 days after transplantation (n = 4 mice/group) or after formation of a palpable tumor (5 mice/group). Tumor weight was estimated weekly by measuring tumor length and width, and retinoid toxic effects were evaluated daily. Two weeks after the final treatment, mice were euthanatized, and number of mice with pulmonary metastases was determined.

Results—Adverse treatment effects were not detected. Tumor weight was less in mice treated with either dose of 9-cis RA than in control mice, although this difference was not significant. Treatment with 30 mg of 9-cis RA/kg initiated after tumor formation significantly reduced the incidence of pulmonary metastasis, compared with the control group.

Conclusions and Clinical Relevance—9-cis RA decreased the incidence of pulmonary metastasis in nude mice transplanted with canine osteosarcoma cells and may be a potential adjunct therapy for treatment of osteosarcoma in dogs. (Am J Vet Res 2000; 61:1241–1244)

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in American Journal of Veterinary Research


Objective—To characterize the clinical features of visceral mast cell tumors (MCT) without associated cutaneous involvement in dogs.

Design—Retrospective study.

Animals—10 dogs with histologically confirmed MCT without associated cutaneous lesions.

Procedure—Information on signalment, clinical signs, laboratory examinations, and time from first admission to death was obtained from the medical record of each dog.

Results—Purebred male dogs of miniature breeds appeared to have a higher prevalence of visceral MCT. Clinical signs included anorexia, lethargy, vomiting, and diarrhea. Anemia (n = 7), hypoproteinemia (5), and mastocythemia (5) were detected. Treatments, including glucocorticoids, were not successful. Primary sites of tumors were the gastrointestinal tract (n = 6) and the spleen or liver (1); the primary site was not confirmed in the remaining 3 dogs. In 7 dogs, tumors were categorized as grade II or III, on the basis of histologic findings. The prognoses were poor, and all dogs died within 2 months after first admission.

Conclusions and Clinical Relevance—Visceral MCT is uncommon in dogs, and the prognosis is extremely poor. Biological behavior and drug susceptibility of visceral MCT may be different from cutaneous MCT. The lack of specific clinical signs may result in delay of a definitive diagnosis. The rapid progression of clinical signs and difficulty in diagnosis contributes to a short survival time. ( J Am Vet Med Assoc 2000;216: 222–226)

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in Journal of the American Veterinary Medical Association