Survival in dogs with nasal adenocarcinoma: 64 cases (1981-1995).

Case records of 64 dogs with nasal adenocarcinoma were reviewed. The effects of age, gender, tumor stage, presence of metastatic lesions, and treatment method on survival time were examined. Surgery groups included rhinotomy (n = 9), transnasal curettage (n = 29), and no surgery (n = 26). Chemotherapy groups included fluorouracil-cyclophosphamide combination therapy (n = 15), mitoxantrone (n = 7), and no chemotherapy (n = 42). Fifty-three dogs received fractionated cobalt 60 radiation therapy. Surgical procedure, chemotherapy group, and stage of primary tumor were not significantly associated with survival time (P > .05). Dogs that received radiation therapy had a significantly longer median survival time (424 days) than dogs that did not (126 days)(P = .0001). The presence of either regional lymph node or pulmonary metastasis was associated with significantly shorter median survival time (109 days) when compared to dogs without metastases (393 days)(P = .0125). When only dogs that had received radiation therapy were considered, neither surgical treatment nor chemotherapy group was associated with significant changes in median survival time. An alternate staging system emphasizing the presence or absence of metastases is proposed.

Response of canine mast cell tumors to treatment with oral prednisone.

Twenty-five dogs with naturally occurring mast cell tumors were treated with daily oral prednisone (1 mg/kg) for 28 days. Five dogs (20%) had reduction in tumor volume and were considered responders. Four of these underwent partial remission and one underwent complete remission. Survival times for the five responders were 3, 5, 6, 7.5, and greater than 28 months, respectively. We therefore conclude that prednisone is effective in some canine mast cell tumors. Further studies are indicated to determine the most effective dose of prednisone, the appropriate duration of treatment, and the efficacy in more benign mast cell tumors, and in combination with other forms of therapy.

Adrenocorticotropic hormone and cortisol concentrations after corticotropin-releasing hormone stimulation testing in cats administered methylprednisolone.

The hypothalamic-pituitary-adrenocortical (HPA) axis was studied in 8 healthy cats after administration of supraphysiologic doses of methylprednisolone (MP). Ovine corticotropin-releasing hormone (oCRH) administration increased cortisol and adrenocorticotropic hormone (ACTH) concentrations. Significant (P < 0.05) suppression of cortisol and a trend toward suppression of ACTH was observed after 1 week of MP administration. The HPA axis quickly recovered from suppressive effects of MP 1 week after administration of the steroid was discontinued. Side effects of oCRH administration were minimal in 7 cats; however, 1 cat had a severe hypotensive reaction. Clinical abnormalities were not associated with MP administration. The HPA axis was suppressed by supraphysiologic doses of MP in all treated cats that lacked clinical signs consistent with iatrogenic HPA axis suppression. Despite the relatively active pars intermedia in cats, compared with human beings and dogs, feedback of MP on the HPA axis resulted in similar trends in oCRH-stimulated ACTH and cortisol concentrations as observed in human beings and dogs. Lack of consistent correlation between ACTH and cortisol concentrations was observed in 3 cats and possibly was related to the active pars intermedia in the cat.

Radiotherapy and hyperthermia in the treatment of fibrosarcomas in the dog.

Ten dogs with oral or external nasal fibrosarcoma were treated sequentially with orthovoltage radiation and radiofrequency (RF)-induced hyperthermia. Total radiation doses ranged from 3,200 to 4,800 rad given in 8 to 12 fractions of 400 rad. Immediately after 2 to 4 radiation treatments, hyperthermia was given. Six oral fibrosarcomas were heated to 50 C for 30 sec, using a hand-held RF generator. Four nasomaxillary fibrosarcomas were heated to 43 C for 30 minutes, using a 500-kHz RF generator. Hyperthermia of 50 C resulted in tumor necrosis and infection in 3 dogs and fatal septicemia in 1 dog. Nine of 10 tumors responded to therapy. One year after therapy, 5 dogs were free of disease. Tumor regrowth occurred in 5 dogs. Mean time to tumor regrowth and mean survival time of all dogs were 343 and 398 days, respectively. The results suggested that sequential radiation-hyperthermia is an effective therapeutic regimen for canine fibrosarcoma. It was concluded that this modality not only may be beneficial in the treatment of canine tumors but may be useful for designing new therapeutic approaches to similar tumors in man.

Hyperthermic treatment of superficial tumors in cats and dogs.

Local current field radiofrequency hyperthermia was applied to 33 superficial tumors in 11 cats and 5 dogs. Squamous cell carcinoma (SCC) in the cat was the most frequent tumor treated. Of 19 SCC in cats, 13 (68%) were reduced completely, combining complete and partial tumor reduction, there was an 89% favorable response to hyperthermia for SCC. A small number of other tumors such as fibrosarcoma in the cat and perianal tumors in the dog were favorably responsive. Local current field hyperthermia (50 C for 30 sec) resulted in destruction of tumor tissue as well as normal tissue. However, tissue destruction did not extend more than 2 or 3 mm from the electrodes. Ulcerative superficial tumors exposed to air rapidly reduced in size, and a dry eschar that developed fell off at 17 to 25 days.

Severe idiopathic thymic hemorrhage in two littermate dogs.

Two 6-month-old littermate Shetland Sheepdogs were found to have severe thymic hemorrhage unassociated with trauma or poisoning. One dog survived the insult with supportive care, and the other died and was necropsied. Antemortem laboratory data and radiographic findings for both dogs were consistent with acute blood loss into the mediastinum. Hemorrhage was restricted to the thymus and mediastinum in both dogs.

Treatment of bovine and equine ocular squamous cell carcinoma by radiofrequency hyperthermia.

Forty-five ocular squamous cell carcinomas (SCC) in 17 cattle and 8 horses were treated by radiofrequency hyperthermia, resulting in 80% complete regression and 16% partial regression. Tumors were histologically diagnosed as SCC; 50% of the tumors were recurrent, having been treated previously by surgery, cryosurgery, radiation, or immunotherapy. After hyperthermic treatment, most animals were available for tumor measurement at 4 to 6 weeks and at 8 to 16 weeks, with a final observation period of 2 to 10 months for all. Complete regression occurred in 8 of 12 tumors given a second hyperthermic treatment. It was concluded that hyperthermia is an effective and easily applied treatment modality for ocular SCC in cattle and horses; however, it cannot be recommended for large tumors (larger than equal to 5 cm diameter) that have deep eyelid or conjunctival penetration.

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.

Hematological and clinical responses to combined mitoxantrone and cyclophosphamide administration to normal cats.

The purpose of this study was to examine the feasibility of a combination chemotherapy protocol ("CYCLONE") in cats, utilizing mitoxantrone and cyclophosphamide. Three normal adult cats were administered mitoxantrone (6.5 mg/m2 intravenously) and cyclophosphamide (100 mg/m2 intravenously) every 21 days for a total of three doses. Individual white blood cell count nadirs (range, 2.0-9.5 x 10(9)/L) and neutrophil count nadirs (range, 0.3 to 5.0 x 10(9)/L) occurred between days 2 and 10 after each dose of chemotherapy. Mean white blood cell count nadirs (range of mean, 5.5 to 8.4 x 10(9)/L) occurred between days 6 and 8, as did the mean neutrophil count nadir (range of mean, 1.7-4.0 x 10(9)/L). Side effects were limited to transient appetite suppression in one cat and loose stools in two cats. Myelosuppression and gastrointestinal side effects were comparable to those observed with single-agent mitoxantrone protocols. Further investigation of this protocol is warranted.

Early-onset leukopenia and severe thrombocytopenia following doxorubicin chemotherapy for tonsillar squamous cell carcinoma in a dog.

Doxorubicin is reported to cause myelosuppression, with a white blood cell count nadir occurring between day 7 and day 10. Thrombocytopenia is less severe and occurs between days 3 and 8. This report presents an early onset of leukopenia (day 5) and a severe thrombocytopenia (4000 platelets/microliter) (day 6) associated with doxorubicin administration for treatment of recurrent tonsillar squamous cell carcinoma in a dog.

Pharmacokinetics and tolerance of weekly OXYGENT CA infusions in the dog.

This study determined the OXYGENT CA (90% w/v perflubron emulsion, Alliance Pharmaceutical Corporation) dose necessary to achieve a 3-4% fluorocrit, and the tolerance of this dose administered once per week for four weeks to dogs. This study simulated OXYGENT CA use as a radiosensitizing agent. Six adult dogs were administered 6 ml/kg OXYGENT CA once per week for 4 weeks. Blood samples were collected following infusion, until fluorocrits were < or = 0.5%. One week after the fourth infusion, three dogs were necropsied. Liver biopsies were obtained from the remaining three dogs which were monitored 12 additional weeks. All dogs achieved fluorocrits > 3.0% (3.5-5.1%) with the 6 ml/kg dose. A 3 ml/kg dose did not provide a fluorocrit > 3.0%. Serum bilirubin concentrations were elevated at 24-hour sampling times and declined within 72 hours. Elevations in ALT, SAP, and bile acids were noted. Splenic and hepatic microvasculature fibrosis occurred in the long-term study dogs. Thrombocytopenia occurred in 5/6 dogs, necessitating exclusions of one dog from 2 infusions. However, 3/5 thrombocytopenic dogs had titers for Ehrlichia sp., which elicits thrombocytopenia. Therefore, we cannot conclude the effect of OXYGENT CA on platelets.

Accuracy of fluorocrit in determination of blood perflubron concentration.

Previous studies examining the radiosensitizing effects of perfluorochemical emulsions have based dose recommendations on a measurement known as fluorocrit. The fluorocrit is the proportion of blood volume occupied by perfluorochemicals and is measured using standard hematocrit procedures. This measurement is inherently crude and subject to error and variability between different individuals measuring the same sample. Furthermore, the fluorocrit method has not been compared to other quantitative methods to determine its reliability. The purpose of this study was to compare fluorocrit measurements to those obtained by gas chromatographic analysis. A 90% w/v perflubron emulsion was administered to six normal dogs once weekly for four weeks and peripheral blood samples were obtained at specified time points for analysis. A total of 123 blood samples were analyzed by both methods. The relationship between blood fluorocrit and plasma perflubron concentration measured by gas chromatography was examined using regression models. Based on the modest predictive value (r2 = 0.3683) of the derived statistical model, we conclude that fluorocrit measurement is an inaccurate method of estimation of blood perflubron concentration. Caution must, therefore, be exercised when extrapolating data and dose recommendations from reports of studies using flurocrit as the only estimate of blood perflubron concentration.