Immunohistochemical assay for detecting estrogen receptors in canine mammary tumors.

OBJECTIVE: To determine the estrogen receptor (ER) content of canine mammary gland tumors by use of immunohistochemical (IHC) examination of formalin-fixed sections. SAMPLE POPULATION: 21 mammary gland tumors from 20 adult dogs. PROCEDURE: ER were detected in formalin-fixed tissues, using an avidin-biotin alkaline phosphatase IHC assay and were quantified on fresh-frozen tumor samples, using a modified dextran-coated charcoal (DCC) assay. RESULTS: 7 of 21 tumors had visually detectable nuclear ER by use of IHC staining, whereas 8 of 21 tumors were positive for ER by use of the DCC assay. The ER-positive cells in 5 IHC-positive tumors were epithelial cells with histologic criteria of early malignancy. The remaining 2 ER-positive tumors detected by use of IHC had ER-positive mast cells within areas of connective tissue around the tumor. CONCLUSIONS: Immunohistochemistry is an additional method for detection of ER in canine mammary tumors. The major advantage of this type of assay is that it may be performed on formalin-fixed tissues, and individual ER-positive cells may be identified. Discovery of ER-positive mast cells by use of IHC is of concern, particularly if the ER status of a tumor is based on DCC results alone. CLINICAL RELEVANCE: Because most canine mammary tumors are fixed in formalin prior to histologic evaluation, an IHC assay that identifies ER-positive cells is desirable. Adjunctive antiestrogen therapy could be administered to dogs with ER-positive tumors.

Prognosis for dogs with nonlymphomatous, small intestinal tumors treated by surgical excision.

Long-term follow-up information was obtained for 39 dogs that had undergone surgical excision of nonlymphomatous, small intestinal tumors. For all dogs evaluated in this study, the median survival time was 10 months, and the one- and two-year survival rates were 40.5% and 33.1%, respectively. There was no difference in survival times between dogs with adenocarcinomas (n=23) and dogs with leiomyosarcomas (n=16). Survival times were significantly (p less than 0.0001) shorter for dogs with histological evidence of metastases at the time of surgery (median, 3.0 months) than for dogs with no histiological evidence of metastases (median, 15.0 months).

Evaluation of dogs and cats with tumors of the ear canal: 145 cases (1978-1992).

OBJECTIVE: To characterize the frequency, clinical signs, biologic behavior, and response to treatment of tumors of the ear canal in dogs and cats. DESIGN: Retrospective analysis of medical records. ANIMALS: Medical records of 81 dogs (48 malignant tumors, 33 benign tumors) and 64 cats (56 malignant tumors, 8 benign tumors). PROCEDURE: Data were analyzed for cats and dogs with malignant tumors, and risk factors were analyzed for their potential impact on survival time. RESULTS: Malignant tumor types most commonly reported included ceruminous gland adenocarcinoma, squamous cell carcinoma, and carcinoma of undetermined origin. Median survival time of dogs with malignant aural tumors was > 58 months, whereas that of cats was 11.7 months. A poor prognosis was indicated by extensive tumor involvement (dogs) and by neurologic signs at time of diagnosis, diagnosis of squamous cell carcinoma or carcinoma of undetermined origin, and invasion into lymphatics or blood vessels (cats). CLINICAL IMPLICATIONS: Malignant tumors of the ear canal in dogs and cats have a propensity for local invasion, but tend not to metastasize. Squamous cell carcinoma and carcinoma of undetermined origin were the most locally aggressive tumors. Malignant tumors of the ear canal are best managed by aggressive surgical excision. Radiotherapy may be useful when tumors cannot be completely removed.

Evaluation of prognostic factors for dogs with synovial sarcoma: 36 cases (1986-1991).

Medical records of 36 dogs with synovial sarcoma confirmed by microscopic examination of H&E-stained sections of tissue were selected for retrospective analysis from dogs admitted between 1986 and 1991 to participating institutions of the Veterinary Cooperative Oncology Group. Metastasis was evident at the time of diagnosis in 8 (22%) dogs, and 15 (41%) dogs ultimately developed metastatic tumors. Median survival time for all dogs, as determined by life-table analysis, was 17 months. For dogs that were subsequently treated and became tumor free, the median disease-free interval was 30 months. Nine dogs had previously had localized excision attempted, but all had recurrence of the tumor locally (median, 4.5 months). Of 29 dogs that underwent amputation, including the 9 with localized recurrence, 2 had tumor recurrence on the amputation stump. Most dogs had survival time and disease-free interval of > 36 months after amputation. Four dogs that had received chemotherapy for tumors of advanced clinical stages did not respond to treatment. One dog that had received locally applied radiotherapy after localized excision did not have evidence of tumor recurrence 2 years after radiotherapy. Clinical stage, histologic grade, and a positive result for tests that used cytokeratin immunohistochemical staining significantly (P < 0.05) influenced survival time and disease-free interval. Analysis of data for the study reported here suggested that histologic criteria can be an excellent predictor of dogs that are likely to have tumor recurrence after amputation and that would most likely benefit from aggressive treatment with adjuvants.

Unexpected neurotoxicity in dogs receiving a cyclophosphamide, dactinomycin, and 5-fluorouracil chemotherapy protocol.

An inexpensive combination chemotherapy protocol containing cyclophosphamide, dactinomycin, and 5-fluorouracil was evaluated in dogs with carcinomas. Fifteen dogs were entered in this study, and there were 1 complete response and 2 partial responses among 12 evaluable dogs. However, 6 of 15 dogs (40%) developed neurotoxicity. The neurotoxicity of this protocol was compared with a previous 5-fluorouracil-containing protocol and found to be significantly higher. Due to the unacceptably high rate of neurotoxicity, this protocol cannot be recommended for use in dogs with cancer.

Systemic toxicity associated with doxorubicin administration in cats.

The systemic toxicity of doxorubicin, 30 mg/m2 body surface area (BSA) every 21 days to a cumulative dose of 300 mg/m2, was evaluated in six cats. Appetite, body weight, and the presence of vomiting and/or diarrhea were monitored throughout the study. Renal function was monitored by measuring serum blood urea nitrogen (BUN) and creatinine concentrations, urine specific gravity, and creatinine clearance before each treatment. Electrocardiograms and echocardiograms were also done before each treatment. The cats were killed 3 weeks after the last treatment, and complete necropsies were performed. Partial or complete anorexia occurred in all cats with significant weight loss occurring after a cumulative doxorubicin dose of 150 mg/m2 BSA. Mild vomiting and diarrhea that required no treatment also occurred sporadically in all cats. Echocardiographic changes consistent with doxorubicin-induced cardiomyopathy occurred in four cats after cumulative doses of 170 to 240 mg/m2 BSA. Clinical heart disease and electrocardiographic changes were not observed. Subsequent histological examination revealed myocyte vacuolization and myocytolysis in all six hearts. Renal dysfunction, characterized by increasing azotemia with progressively more dilute urine, was detected in two cats. Mean creatinine clearance values also decreased significantly throughout the study. At necropsy, all cats had histological evidence of renal disease.

Hematologic toxicosis associated with doxorubicin administration in cats.

The hematologic toxicity of doxorubicin, 30 mg/m2 body surface area (BSA) every 21 days to a cumulative dose of 300 mg/m2, was evaluated in six cats. Complete blood and platelet counts were performed daily during the first treatment cycle. They were monitored before treatment for all remaining cycles, and at the average neutrophil nadir (day 8) starting with cycle 4. Significant poikilocytosis developed after the first treatment and remained throughout the study, although anemia did not occur. No other red blood cell abnormalities were seen. Platelet counts remained within the reference range throughout the first treatment cycle, but mild thrombocytopenia (88,000-288,000/uL) was found in 11.3% of subsequent complete blood counts (CBCs). Thrombocytosis was seen in 30.9% of CBCs. Neutropenia did not occur during the first treatment cycle although neutrophil counts did decrease, with the nadir occurring between days 8 and 11. All neutrophil counts returned to pretreatment values by day 14. Neutropenia was documented after 14 of 46 (30.4%) doxorubicin treatments, and was associated with fever in 5 cats (10.9%). All fevers responded to oral antibiotic therapy. Neutropenia that lasted more than 14 days developed in two cats, necessitating dosage reduction to 25 mg/m2 BSA. At the dose used in this study, doxorubicin administration was associated with acceptable hematologic toxicosis in most cats.

Kinetics of a rapid, luminol dependent chemiluminescence signal induced in HL-60 cells by amphotericin B and other stimulants.

Addition of the polyene antibiotic amphotericin B or tissue culture medium to nondifferentiated HL-60 cells in the presence of luminol induces a chemiluminescence signal that reaches a peak value within a few seconds and decays exponentially in less than a minute. The kinetics of the signal and its modulation by superoxide dismutase, catalase, and horseradish peroxidase are consistent with a series of solution biochemical processes with a rate-determining step corresponding to the disproportionation of a luminol-superoxide complex. The effects of the enzymes demonstrate that superoxide is a precursor to the rate-determining intermediate and that both catalase and peroxide enhance a reaction that competes with the rate-limiting process.

Canine mast cell tumors.

Mast cell tumors (MCTs) are common in the dog, occurring most frequently in the skin and subcutaneous tissues. Their biologic behavior can be quite variable, with approximately 50% being malignant. Although clinical features and histologic grading can help determine the likelihood of malignancy, it is difficult to predict the biologic behavior of an individual tumor. Consequently, all MCTs should be considered potentially malignant. Wide surgical excision is the most common therapy for canine MCTs, although approximately 50% recur locally. Nonresectable or recurrent MCTs can be treated with radiation and/or chemotherapy. Chemotherapy is also used in the treatment of metastatic MCTs, and it may be helpful in preventing the recurrence and/or metastasis of undifferentiated tumors.

Toxicology of oncologic drugs.

The drugs used in clinical oncology are inherently toxic because they are designed to kill host cells. For the most part, the toxic effects occur in tissues with high growth fractions--that is, bone marrow, gastrointestinal epithelium, and hair follicles. Nevertheless, certain drugs do cause harm to other organs. At therapeutic doses of anticancer drugs, the toxicoses are usually mild to moderate and can be managed without undue discomfort to the animal. Occasionally, however, life-threatening cytopenias occur. By contrast, with drug overdose, life-threatening toxicoses can be a very real concern.

Coagulation abnormalities associated with neoplasia.

Subclinical abnormalities in hemostasis occur commonly in small animal patients with cancer, but the incidence of clinical thrombosis or hemorrhage is unknown. Malignancy can lead to abnormalities in both primary and secondary hemostasis, which in turn can lead to either thrombotic or hemorrhagic tendencies. These coagulation abnormalities can be associated with the tumor itself, with anticancer chemotherapy, or with secondary organ dysfunction. Thrombocytopenia and DIC are probably the most common defects associated with clinical bleeding in small animal patients.

Fine-needle aspiration of the spleen as an aid in the diagnosis of splenomegaly.

Results from transabdominal fine-needle aspiration of the spleen in 28 dogs and 5 cats are reported. Splenomegaly was present in 79% of these patients, and splenic masses were present in 15%. Extramedullary hematopoiesis, the most common cytologic diagnosis, was found in 24% of the patients and was associated with a variety of diseases including immune hemolytic anemia, hemangiosarcoma, and bone marrow hypoplasia. Hematopoietic neoplasms including lymphosarcoma, plasmacytoma, myelogenous leukemia, and systemic mastocytosis were diagnosed in 24% of the patients. Other diagnoses included malignant neoplasia of undetermined cell type and lymphoreticular hyperplasia. Splenic aspirates were considered normal in 18% of the animals. Two (6%) of the aspirates contained liver tissue rather than spleen. Histologic evaluation of splenic tissue was performed in 42.5% of the patients. All cytologic diagnoses correlated well with their final histologic diagnoses. Complications from the aspiration procedure were not observed, even in thrombocytopenic patients.

Cyclic hematopoiesis associated with feline leukemia virus infection in two cats.

Cyclic oscillations in the numbers of blood elements were detected in 2 cats with FeLV infection. Periodic neutropenia, followed by a return to normal neutrophil numbers, was detected in both cats. The mean cycle duration was 11.8 days, with a range of 8 to 14 days. Just before the return of normal neutrophil numbers, monocytosis developed. In 1 cat, cyclic variations in the number of reticulocytes and platelets also were detected. Bone marrow aspirates obtained during periods of neutropenia had a predominance of progranulocytes in the myeloid cell line. myeloid hyperplasia, with numerous segmented neutrophils, was seen in bone marrow aspirates obtained during periods of normal neutrophil numbers. Oral administration of prednisolone resulted in cessation of the cyclic oscillations of blood elements in 1 cat. Cyclic hematopoiesis appeared to be another non-neoplastic manifestation of FeLV infection.

Systemic mastocytosis in 16 dogs.

The clinical and pathologic features of systemic mastocytosis in 16 dogs are reported. There was no apparent breed or sex predilection, and the median age at presentation was 9.5 years. In 14 of 16 cases there was a primary cutaneous mast cell tumor (MCT). When cutaneous tumor location was compared with previous reports, there was no association between location and systemic dissemination. The most common presenting signs associated with the cutaneous tumor were regional dissemination, edema, ulceration, and abscessation. They were present in 12 dogs (69%). Signs of systemic illness, including anorexia, vomiting, and diarrhea, were seen in eight dogs (50%). Other than the cutaneous tumors, the most consistent physical and radiographic abnormalities included lymphadenopathy, splenomegaly, and hepatomegaly. Eosinophilia and basophilia were seen in two and five dogs, respectively. Six dogs had increased numbers of mast cells in peripheral blood or buffy coat smears. Five of the nine dogs evaluated had increased numbers of mast cells in bone marrow aspirates. Bone marrow aspiration was superior to both peripheral blood and buffy coat smears in predicting mastocytosis. Coagulation abnormalities were seen in three of five dogs tested. Using a conventional histomorphologic grading system, 10 of 13 (77%) tumors were classified as Grade III or undifferentiated and were overrepresented when compared with previous reports of cutaneous MCTs. Eighty-eight percent of the dogs either died or were euthanatized because of their tumors. Organs commonly involved at necropsy included lymph nodes, spleen, liver, and bone marrow; four dogs had gastroduodenal ulcers.