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Objective

To assess the efficacy and determine prognostic factors of megavoltage irradiation for pituitary macrotumors in dogs with neurologic signs.

Design

Prospective clinical trial.

Animals

24 dogs with pituitary macrotumor syndrome; 19 ACTH-secreting and 5 clinically endocrine-inactive tumors.

Procedure

Dogs were treated with 48 Gy of radiation during 4 weeks on an alternate-day schedule of 4 Gy/fraction. Three (12.5%) dogs did not complete the planned treatment because of progression of neurologic signs.

Results

A significant correlation was found between relative tumor size (ie, size of tumor relative to calvarium size) and severity of neurologic signs and between relative tumor size and remission of neurologic signs after irradiation. In dogs with pituitary dependent hyperadrenocorticism, a significant correlation was found between relative tumor size and plasma endogenous ACTH concentrations. Prognostic factors that independently affected duration of remission of neurologic signs were relative tumor size and endocrine activity. The prognostic factor that independently affected overall survival time was severity of neurologic signs. Prognostic factors of duration of eucortisolism were not found. Use of a large field of irradiation was associated with substantial damage to brain tissue.

Clinical Implications

Because radiation therapy was effective for treatment of tumors of small relative size in dogs, early treatment of pituitary tumors should improve prognosis. Further improvements may be obtained, using protocols in which higher total radiation doses and smaller radiation dose fractions are given. Irradiation was effective for long-term control of functional pituitary macrotumors and resulted in acceptably low complication rates when small fields of radiation were used. (J Am Vet Med Assoc 1998;213:225-231)

Free access
in Journal of the American Veterinary Medical Association

Summary

One hundred twenty cats with hyperthyroidism were treated with radioiodine (131I); 60 cats were administered radioiodine sc, and 60 cats were administered radioiodine iv. Before treatment, radioactive tracer studies were performed on each cat to determine peak radioactive iodine uptake and effective half-life. These data were used to calculate the dose of radioiodine that would have to be given to each cat to deliver 150 Gy to the thyroid tissue. The 2 groups of cats were similar with regard to age, tracer study results, and radioiodine dose. Mean estimated thyroid mass was larger for cats treated iv, but mean serum thyroxine concentration was higher for cats treated sc. Route of administration did not affect thyroidal uptake of radioiodine. However, radiation exposure of personnel was significantly lower with sc administration than with iv administration, even when iv catheterization was performed Eighty-five percent of cats treated iv and 84% of cats treated sc were euthyroid 4 years after treatment. Six percent of the cats became hypothyroid after treatment. When compared with iv administration, sc administration of radioiodine appeared to be as effective for treatment of hyperthyroidism, safer to personnel, and less stressful to the cats.

Free access
in American Journal of Veterinary Research

Objective

To determine quality and duration of progression-free survival (PFS) time in dogs with malignant oral tumors after definitive megavoltage irradiation, to analyze prognostic factors for PFS time and patterns of failure, and to analyze the influence of tumor recurrence and development of metastasis on survival.

Design

Prospective clinical trial.

Animals

105 dogs with squamous cell carcinoma, fibrosarcoma, or malignant melanoma of the oral cavity without evidence of metastasis.

Procedure

Dogs were treated with 48 Gy over 4 weeks on an alternate-day schedule of 4 Gy/fraction. Multivariate analysis was done by use of Cox's regression model to determine significant prognostic factors and by use of a competing risk model to determine the differential effects of prognostic factors on type of, and time to, failure. In 8% of the dogs, severe acute radiation reactions in the final week of treatment resulted in treatment discontinuation. In 7.6% of the dogs, chronic radiation reactions, including bone necrosis and fistula formation, developed.

Results

Prognostic factors that independently affected PFS time were histologic type and tumor T stage. Histologic type significantly influenced pattern of failure, but not time to failure, whereas clinical stage significantly influenced time to failure, but not type of failure.

Clinical Implications

Irradiation was a safe and effective treatment of malignant oral tumors. Because the local efficacy of radiation was influenced only by tumor size, early treatment of oral tumors should improve the prognosis. In dogs without tumor recurrence, systemic metastases, rather than regional metastases, limited long-term survival after radiation therapy. (J Am Vet Med Assoc 1997;210:778–784

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To develop a slow-release carboplatin formulation for intratumoral administration to cats.

Design

Preliminary study to analyze pharmacokinetic effects of purified sesame oil in the carboplatin formulation for intratumoral administration, and a second study to evaluate the efficacy and toxicosis of intratumoral administration of carboplatin in purified sesame oil.

Animals

23 cats with squamous cell carcinomas of the nasal plane.

Procedure

Eight cats with advanced-stage tumors were submitted to intratumoral administration of 100 mg of carboplatin/m2 of body surface area, with or without purified sesame oil, using a two-period, cross-over design. Fifteen additional cats were treated by intratumoral administration of carboplatin in purified sesame oil. Four weekly intratumoral chemotherapy injections of carboplatin in purified sesame oil at a dosage of 1.5 mg/cm3 of tissue were given.

Results

Purified sesame oil in the formulation significantly reduced systemic exposure to carboplatin and drug leakage from the sites of injection. Cumulative effects of repeated intratumoral administrations on plasma concentrations of carboplatin were not observed. Systemic toxicosis was not observed, and local toxicosis was minimal. Healing of ulcerated lesions was not compromised. Rates of complete clinical tumor clearance and complete response were 67 and 73.3%, respectively. Product-limit estimates of mean progression-free survival times was 16 ± 3.3 months. The 1-year progression-free survival rate was 55.1 ± 13%. Local recurrence was observed in 7 cats; 4 had marginal tumor recurrence, and 3 had in-field and marginal tumor recurrence.

Conclusions

Intratumoral carboplatin chemotherapy is safe and effective for cats with squamous cell carcinoma of the nasal plane. Future studies to improve treatment efficacy could include evaluation of increased dose-intensity as well as combination of this modality with radiotherapy.

Clinical Relevance

Intratumoral administration of carboplatin in a water-sesame-oil emulsion was found to be a practical and effective new treatment for facial squamous cell carcinomas in cats.

Free access
in American Journal of Veterinary Research

Summary:

Twenty horses with 30 lesions were studied to evaluate the effects of intratumoral chemotherapy with cisplatin in sesame oil on equine sarcoids (n = 19), squamous cell carcinomas (n = 7), and squamous cell papillomas (n = 4). Treatment consisted of 4 sessions of intratumoral cisplatin chemotherapy at 2-week intervals. A controlled-release formulation of cisplatin in sesame oil was used to limit drug egress from the injection site. Mean dosage per session was 0.97 (±0.17, sem) mg of cisplatin/cm3 of tumor tissue treated for tumor volumes ranging from 10 to 20 cm3. Dosage tended to be slightly higher for smaller tumors and slightly lower for larger tumors. Tumor regression was observed in all horses. Complete response was observed in 18 of the sarcoids, 5 of the squamous cell carcinomas, and 4 of the squamous cell papillomas. The mean relapse-free interval was 21.6 and 14 months in horses with sarcoid and carcinoma/papilloma, respectively. The 1-year relapse-free rates were 87 and 65% for equine sarcoid and carcinoma/papilloma, respectively. In horses with relapse, 70% had tumor recurrence outside the treated field. Cisplatin-related local toxicosis was minimal. Intratumoral cisplatin chemotherapy was found to be a practical and effective treatment of sarcoid and squamous cell carcinoma/papilloma in horses.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine progression-free and overall survival times of cats with squamous cell carcinoma (SCC) of the nasal planum following treatment with a single fraction of strontium Sr 90 (90Sr).

Design—Retrospective case series.

Animals—49 cats with SCC of the nasal planum.

Procedures—Information including FIV infection status, diagnosis of SCC vs SCC in situ (ie, evidence that the tumor did or did not penetrate the epidermal basement membrane, respectively), 90Sr dose and number of probe applications, treatment-related response and complications, and recurrence of SCC and new lesion development was obtained from medical records. The relationships of these variables with calculated progression-free and overall survival times were assessed.

Results—Of 49 cats that underwent 90Sr plesiotherapy (median dose, 128 Gy), 48 (98%) had a response to treatment and 43 (88%) had a complete response. Median progression-free and overall survival times were 1,710 and 3,076 days, respectively. Treatment complications were infrequent (4 [8%] cats) and mild. Following treatment, the SCC recurrence rate was 20% (10/49 cats); 16 (33%) cats developed new lesions in other locations. Overall survival time was significantly longer for cats with a complete response to treatment than for those with a partial response. None of the other variables evaluated had a significant effect on progression-free or overall survival time.

Conclusions and Clinical Relevance—Treatment of cats with SCC of the nasal planum with a single fraction of 90Sr appeared to be effective and well tolerated. Initial response to treatment was predictive of overall survival time.

Full access
in Journal of the American Veterinary Medical Association

Objective

To determine quality and duration of progression-free survival (PFS) time in dogs with periodontal tumors after definitive megavoltage irradiation and to analyze prognostic factors for PFS time and patterns of treatment failure.

Design

Prospective clinical trial.

Animals

47 dogs with acanthomatous, fibromatous, or ossifying epulis.

Procedure

Dogs were treated with 48 Gy over 4 weeks on an alternate-day schedule of 4 Gy/fraction. Multivariate analysis was done by use of Cox's proportional hazards regression model to determine prognostic factors for PFS time.

Results

The only independent prognostic factor for PFS time was tumor T stage. Pattern of local tumor recurrence (marginal vs infield regrowth) was independent of clinical stage, tumor location, and site. In 4% of the dogs, severe acute radiation reactions in the final week of treatment resulted in treatment discontinuation. In 6.4% of the dogs, chronic radiation reactions included bone necrosis.

Clinical Implications

Irradiation was a safe and effective treatment of small (T1 and T2 stage) periodontal tumors. The usefulness of the radiation protocol in this study is limited in dogs with large (T3) tumors, particularly those located in the caudal half of the oral cavity, because of poor results and high risk of acute radiation toxicoses. (J Am Vet Med Assoc 1997;210:785–788

Free access
in Journal of the American Veterinary Medical Association

Summary

Five radiographic protocols for detecting pulmonary metastases in dogs were compared by analyzing receiver operating characteristic curves for the protocols. Protocols compared were a right lateral view only, a left lateral view only, right lateral and dorso- ventral views, both lateral views, and all 3 views. Three radiologists used each of the protocols to evaluate 99 sets of thoracic radiographs. Fifty-two sets of radiographs were from dogs confirmed histologically to have pulmonary metastases and 47 were from dogs proven at necropsy to be free of pulmonary metastases. Results of the 5 protocols were not statistically different. We concluded that a third view is not necessary when routinely screening dogs with cancer for pulmonary metastases and that the standard 2-view thoracic examination should be adequate. However, in individual cases, a third view may be the determining factor in establishing a radiographic diagnosis and should be obtained if any suspicious areas are seen.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the incidence of bovine papillomavirus (BPV) type 1 or 2 in sarcoids and other samples of cutaneous tissues collected from horses in the western United States.

Animals—55 horses with sarcoids and 12 horses without sarcoids.

Procedure—Tissue samples (tumor and normal skin from horses with sarcoids and normal skin, papillomas, and nonsarcoid cutaneous neoplasms from horses without sarcoids) were collected. Tissue samples were analyzed for BPV-1 or -2 DNA, using a polymerase chain reaction (PCR) and restriction fragment length polymorphism. The PCR products from 7 sarcoid- affected horses were sequenced to evaluate percentage homology with expected sequences for BPV-1 or -2.

Results—Most (94/96, 98%) sarcoids contained BPV DNA. Sixty-two percent of the tumors examined had restriction enzyme patterns consistent with BPV-2. Thirty-one of 49 (63%) samples of normal skin obtained from horses with sarcoids contained BPV DNA. All samples subsequently sequenced had 100% homology with the expected sequences for the specific viral type. All tissues from healthy horses, nonsarcoid neoplasms, and papillomas were negative for BPV DNA.

Conclusions and Clinical Relevance—Bovine papillomaviral DNA was detected in essentially all sarcoids examined. There appears to be regional variation in the prevalence of viral types in these tumors. The fact that we detected viral DNA in normal skin samples from horses with sarcoids suggests the possibility of a latent viral phase. Viral latency may be 1 explanation for the high rate of recurrence following surgical excision of sarcoids. (Am J Vet Res 2001;62:741–744)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine expression of a transforming gene (E5) of bovine papillomavirus in sarcoids, other tumors, and normal skin samples collected from horses with and without sarcoids.

Sample Population—23 sarcoids and 6 samples of normal skin obtained from 16 horses with sarcoids, 2 samples of normal skin and 2 papillomas obtained from horses without sarcoids, and 1 papilloma obtained from a cow.

Procedure—Protein was extracted from tissue samples collected from horses and incubated with agarose beads covalently coupled to Staphylococcus aureus protein A and an anti-E5 polyclonal antibody. Following incubation, proteins were eluted from the beads and electrophoresed on a 14% polyacrylamide gel and transferred to a polyvinylidene difluoride membrane. The E5 protein was detected by use of western blot analysis, using a chemiluminescence detection system.

Results—All 23 sarcoids had positive results for expression of E5 protein. Quantity of viral protein appeared to vary among sarcoids. All other tissues examined had negative results for E5 protein. Highest expression for E5 protein was observed in biologically aggressive fibroblastic variants of sarcoids, compared with expression in quiescent tumors.

Conclusions and Clinical Relevance—This study documented that activation and expression of the E5 gene is evident in sarcoids obtained from horses. These data support the conclusion that infection with bovine papillomavirus is important in the initiation or progression of sarcoids in horses. Treatment strategies designed to increase immune recognition of virally infected cells are warranted. (Am J Vet Res 2001;62:1212–1217)

Full access
in American Journal of Veterinary Research