Uses and effectiveness of pamidronate disodium for treatment of dogs and cats with hypercalcemia

Uncorrected hypercalcemia can cause clinical signs such as polyuria, polydipsia, vomiting, diarrhea, lethargy, and depression and contributes to the development of primary renal failure and soft tissue mineralization. Treatment of hypercalcemia includes diagnosis and treatment of the underlying disease process and some combination of excracellular fluid volume expansion by administration of fluids intravenously and administration of glococorticosteroids, salmon calcitonin, and furosemide. Bisphosphonates such as pamidronate disodium also may be safe and effective in the treatment of hypercalcemia. The purpose of our study was to characterize the efficacy and safety of pamidronate in the treatment of hypercalcemia attritutable to several different disease processes in the dog and cat. Seven dogs and 2 cats were administered pamidronate at a dose of 1.05-2.0 mg/kg IV for a variety of disease processes, including neoplasia (n = 4), calcipotriene toxicity (n = 3), nocardiosis (n = 1), and idiopathic hypercalcemia with chronic renal failure (n = 1). In all the animals, IV pamidronate administration rapidly decreased serum calcium concentrations without evident toxicosis. Two animals received pamidronate several times without obvious toxicosis. On the basis of the findings in our retrospective study, pamidronate may be a safe and effective drug with which to lower both serum total and ionized calcium concentrations in patients with hypercalcemia arising from a wide variety of underlying disease processes.     

Evaluation of Single-Agent Mitoxantrone as Chemotherapy for Relapsing Canine Lymphoma

Many chemotherapeutic regimens will induce remission in dogs with lymphoma, but almost all dogs suffer relapse. Mitoxantrone was selected for evaluation as single-agent chemotherapy for relapsing canine lymphoma based on its use in humans undergoing salvage chemotherapy for non-Hodgkin's lymphoma and its tumoricidal effect against canine lymphoma. Dogs entered into study had multicentric lymphoma, and all had been treated solely with a standard combination chemotherapy protocol. At 1st relapse, all dogs were again staged and underwent lymph node biopsy. Mitoxantrone was administered IV at 6 mg/m² every 21 days. Dogs were evaluated for lymphadenopathy before each dose of mitoxantrone. Fifteen dogs were entered into study. The average age (±SEM) of the dogs studied was 7.7 ± 0.91 years, and most dogs were large (mean ± SEM weight, 24.44 ± 2.15 kg). Twelve dogs (80%) had B-cell lymphoma, and 3 had T-cell lymphoma. Dogs were staged IV (n = 12) or V (n = 3). The median duration of chemotherapy before entry into the study was 98 days. Overall median duration of response after mitoxantrone chemotherapy was 21 days. Complete responses were attained in 7 of 15 dogs (47%) with a median response duration of 84 days. Nine of 15 (60%) dogs attained a complete remission with additional chemotherapy after failing mitoxantrone chemotherapy. Mild toxicities were observed after mitoxantrone administration. No adverse reactions were observed during mitoxantrone infusions. The results of this study demonstrate that mitoxantrone, as a single agent, has limited value for dogs with lymphoma at 1st relapse after conventional multidrug chemotherapy.     

Vascular endothelial growth factor expression in canine intracranial meningiomas and association with patient survival

BACKGROUND: Vascular endothelial growth factor (VEGF) is a regulator of angiogenesis and vascular permeability. In human patients with meningiomas, increased VEGF expression is predictive of postsurgical recurrence. The objectives of this study were to evaluate VEGF expression in canine intracranial meningiomas and to determine whether an association between VEGF expression and patient survival existed. METHODOLOGY: Tumor tissue from 17 dogs with histologically confirmed intracranial meningiomas was obtained surgically. All dogs then were treated with radiotherapy. Immunohistochemistry was performed on 5-microm sections of paraffin-embedded tumor tissue with rabbit anti-human VEGF polyclonal antibody. The extent, intensity, and distribution of VEGF staining for each section were assessed with light microscopy by means of a semiquantitative scale. Survival was analyzed by the Kaplan-Meier procedure. Survival rates among groups were compared by log-rank tests with the significance set at P < or = .05. FINDINGS: VEGF expression was detected in all tumors, with >50% of cells staining positively in tissues from 15/17 dogs. Shorter survival times were associated with greater VEGF expression (P = .01). CONCLUSIONS: VEGF expression can be measured in canine intracranial meningiomas and may be associated with poor outcome. SIGNIFICANCE: The extent of VEGF expression in canine intracranial meningiomas may be used as a prognostic marker and suggests a potential future target for therapy.