Radioiodide (131I) therapy for the treatment of canine thyroid carcinoma

OBJECTIVE: To assess the efficacy of radioactive iodine treatment (131I) for canine thyroid carcinoma, as both the sole therapeutic modality and as an adjunct to surgery. DESIGN: Retrospective analysis of case records from the Gladesville Veterinary Hospital Nuclear Medicine Service, Sydney, between August 1988 and December 2001. CASE DETAILS: The records of 65 dogs with thyroid carcinoma were analysed according to therapy and outcome. Forty-three dogs received radioiodide therapy, either as the sole therapeutic modality (32) or as an adjunct to surgery (11). Radioisotope therapy consisted of one to three doses of 131I with a dose range of 555 to 1850 MBq. For analysis, dogs were divided into groups according to therapy: no treatment, surgery alone, surgery with radioiodide therapy or radioiodide therapy alone. Mode of therapy, dosage of 131I, clinical staging and age were all independently analysed according to survival to compare efficacy or predictive value respectively. RESULTS: When radioiodide therapy was used as an adjunct to surgery, median survival was 34 months. Censored median survival time for dogs that received radioiodide alone was 30 months. Dogs that did not receive treatment had a median survival of only 3 months. Log rank statistical analysis indicated that mode of therapy was significantly correlated with survival but that clinical stage of disease was not. CONCLUSION: The authors conclude that 131I therapy is effective at extending survival time, both as a sole therapeutic modality and as an adjunct to surgery, in dogs with invasive canine thyroid carcinoma. Incomplete surgical resection may not prolong survival in dogs also receiving 131I therapy, however surgical resection with curative intent should be recommended as the first line of therapy for mobile thyroid carcinomas. Radioisotope therapy can be recommended for cases where surgery alone is considered unlikely to be curative because of metastatic disease or local invasion, or for cases where surgery has been attempted but complete surgical removal has not been achieved.     

Prognostic factors and patterns of treatment failure in dogs with unresectable differentiated thyroid carcinomas treated with megavoltage irradiation

OBJECTIVE: To determine quality and duration of progression-free survival (PFS) time in dogs with unresectable thyroid carcinomas treated with definitive megavoltage irradiation and analyze prognostic factors of PFS and patterns of failure (local recurrence vs metastasis). DESIGN: Prospective clinical trial. ANIMALS: 25 dogs with locally advanced thyroid carcinomas and no evidence of metastasis. PROCEDURE: Dogs were treated with 48 Gy during 4 weeks on an alternate-day schedule of 4 Gy/fraction. RESULTS: Irradiation was safe and effective for treatment of large unresectable thyroid carcinomas. Progression-free survival rates were 80% at 1 year and 72% at 3 years. Time to maximum tumor size reduction ranged from 8 to 22 months. Factors affecting PFS were not found. Twenty-eight percent (7/25) of dogs developed metastasis. Dogs with bilateral tumors had 16 times the risk of developing metastases, compared with dogs with a single tumor. Dogs with no evidence of tumor progression had 15 times less risk of developing metastases. Radiation-induced hypothyroidism was suspected in 2 dogs 13 and 29 months after irradiation. CONCLUSIONS AND CLINICAL RELEVANCE: Irradiation is effective for local control of thyroid tumors, despite their slow regression rate. Results provided evidence that local tumor control affects metastatic outcome in dogs with thyroid carcinomas and is a strong basis for the development of new approaches that include irradiation in the management of dogs with advanced thyroid carcinomas. Improvements in local tumor control alone may be insufficient to improve survival times because of the high risk of metastatic spread before an initial diagnosis is made, which warrants initiation of early systemic treatment.     

COMPARISON BETWEEN CLINICAL,ULTRASOUND, CT,MRI, AND PATHOLOGY FINDINGS IN DOGS PRESENTED FOR SUSPECTED THYROID CARCINOMA

This study compares clinical, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and pathology findings in 16 prospectively, and seven retrospectively recruited dogs presented for suspected thyroid carcinoma. Of these, 17 were confirmed thyroid carcinoma, while six were initially misdiagnosed. These included four carotid body tumors, one para‐esophageal abscess, and one undifferentiated squamous cell carcinoma. Thyroid carcinomas occurred in older dogs without evidence of sex predilection, and were more often unilateral. All were large, heterogeneous, moderately to strongly vascularized, and most commonly contained areas of dystrophic mineralization and/or fluid accumulations. On MRI, thyroid carcinomas appeared hyperintense compared to surrounding musculature in all imaging sequences used, while on CT they had a lower attenuation value than normal thyroid gland tissue. Histologically confirmed tumor capsule disruption with invasion of the surrounding structures was most commonly detected with MRI. Palpation was not an accurate predictor of locally invasive vs. well‐encapsulated masses. Computed tomography had the highest specificity (100%) and MRI had the highest sensitivity (93%) in diagnosing thyroid carcinoma, while ultrasound had considerably lower results. We conclude that ultrasound is adequate for use as a screening tool for dogs with suspected thyroid carcinoma, but recommend either CT or MRI for preoperative diagnosis and staging.     

Sodium iodide I 131 treatment of dogs with nonresectable thyroid tumors: 39 cases (1990-2003)

OBJECTIVE: To determine outcome for dogs with nonresectable thyroid carcinomas treated with sodium iodide I 131 and identify factors associated with outcome. DESIGN: Retrospective case series. Animals-39 dogs. PROCEDURES: A definitive or presumptive diagnosis of thyroid tumor was made on the basis of cytologic or histologic examination, abnormal accumulation of sodium pertechnetate Tc 99m during scintigraphy, or both, and dogs were treated with sodium iodide I 131. Dogs with cervical thyroid tumors were evaluated 3 to 6 weeks after 131I therapy, and residual tumor was resected when feasible. RESULTS: Prior to 131I therapy, 32 dogs had a solitary mass and 7 had metastases; 21 were hyperthyroid, 16 were euthyroid, and 2 were hypothyroid. Median survival time for dogs with local or regional tumors (ie, stage II or III) was significantly longer (839 days) than median survival time for dogs with metastasis (366 days). Tumor site (cervical vs ectopic), dose of sodium iodide I 131, age, body weight, treatment (131I therapy alone vs 131I therapy followed by surgery), and serum T4 concentration prior to 131I therapy were not significantly associated with survival time. Three dogs died of radioiodine-associated myelosuppression within 3 months after treatment, but no specific factor associated with development of toxicosis was identified. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that 131I therapy may result in prolonged survival times in dogs with nonresectable thyroid tumors, regardless of serum thyroxine concentration prior to treatment. Dogs undergoing 131I therapy should be monitored for signs of bone marrow suppression.     

131‐I therapy for Advanced, Unresectable Thyroid Tumors in Dogs

Introduction:  Greater than 50% of dogs with thyroid tumors present with surgically unresectable disease for which external beam radiotherapy has been reported to prolong survival. The success of ¹³¹I for control of thyroid tumors in cats and in humans suggests such therapy may also play a role in the management of canine thyroid cancer.
Methods:  Thirty‐nine dogs with WHO stage II/III (invasive or ectopic; n = 32) or IV (metastatic; n = 7) thyroid tumors were treated with ¹³¹I alone. Changes in thyroid function, ^99MTc‐pertechnetate (^99MTc) scintigraphic changes, and tumor response were recorded. Dogs with ventral cervical tumors were evaluated for feasibility of surgical resection following ¹³¹I.
Results:  Median overall survival was 839 days and 366 days for dogs with stage II/III and stage IV tumors, respectively. Thyroid hormone status, site and surgical resection were not associated with outcome in dogs with stage II/III tumors. Three dogs developed severe bone marrow suppression.
Conclusions:  These findings suggest ¹³¹I should be investigated more thoroughly in dogs with thyroid tumors not considered surgical candidates to more clearly characterize the indications for therapy and followup recommendations. ¹³¹I dosimetry in dogs with thyroid tumors remains problematic. Administration of ¹³¹I is currently based on empiric recommendations and, in general, the treatment is well tolerated although additional studies are indicated to optimize response and minimize toxicity.     

Clinical Features and Treatment Outcomes of 41 Dogs with Sublingual Ectopic Thyroid Neoplasia

Background

Thyroid neoplasia is common in dogs, but there are few reports of dogs with ectopic, sublingual thyroid tumors.

Objectives

To describe clinical features and outcomes of dogs with ectopic, sublingual thyroid neoplasia.

Animals

Five hundred and forty‐four dogs with thyroid neoplasia.

Methods

This retrospective study reviewed the medical records of dogs referred for thyroid neoplasia between 1995 and 2013. Data extracted included signalment, extent of thyroid disease (eutopic or ectopic; metastasis), serum thyroxine (T₄) concentration, treatment, and survival.

Results

Of 544 dogs with thyroid neoplasia, 41 (7.5%) dogs had ectopic sublingual thyroid tumors. The clinical features of these 41 dogs were similar to the cohort group of 503 dogs with eutopic or ectopic mediastinal thyroid tumors, but dogs with sublingual tumors were younger and less likely to have metastatic disease (15% versus 30%, P < .05). Of the 41 dogs, 28 received treatment: 21 with surgery (which included partial hyoidectomy in 13), 7 with radioiodine alone, and 13 with surgery followed by administration of radioiodine. Overall median survival was 562 days (range, 1‐1,850 days).

Conclusions and Clinical Importance

When compared with eutopic thyroid carcinomas, ectopic sublingual thyroid tumors generally have a less aggressive biologic behavior. Many dogs have prolonged survival, even without treatment, although death because of local tumor invasiveness or metastasis can develop in some dogs. Surgical thyroidectomy, including partial hyoidectomy, is generally effective for control of local disease. Administration of radioiodine, alone or in combination with surgical treatment, is recommended for multifocal disease or metastasis.     

Thyroid tumors in dogs and cats.

The clinical presentation and biologic behavior of thyroid tumors vary widely among dogs, cats, and human beings. Although thyroid tumors in dogs are rare, they are most likely to be malignant. Clinical signs are usually the result of impingement on surrounding structures, and clinical hyperthyroidism is rare. In contrast, hyperthyroidism resulting from benign thyroid proliferation is relatively common among older cats. Malignant tumors are extremely uncommon but have high metastatic potential. Irrespective of the tumor's ability to produce functional thyroid hormone, scintigraphy is often helpful in the diagnosis and staging of thyroid tumors in all three species. Treatment with surgery is a reasonable treatment option for noninvasive tumors. Iodine 131 is a well-established treatment for thyroid nodules in cats, but its effectiveness in dogs is controversial. In dogs, external beam radiation therapy has produced more consistent results in affording local tumor control when surgery is not possible.     

Computer-assisted image analysis of neovascularization in thyroid neoplasms from dogs

OBJECTIVE: To develop a computer-assisted image analysis procedure for quantitation of neovascularization in formalin-fixed paraffin-embedded specimens of thyroid gland tissue from dogs with and without thyroid gland neoplasia. SAMPLE POPULATION: 47 thyroid gland carcinomas, 8 thyroid gland adenomas, and 8 specimens of thyroid tissue from dogs without thyroid gland abnormalities (normal). PROCEDURE: Serial tissue sections were prepared and stained with antibodies against human CD31 or factor VIII-related antigen (factor VIII-rag). The areas of highest vascularity were identified in CD31-stained sections, and corresponding areas were then identified in factor VIII-rag-stained sections. Image analysis was used to calculate the total vascular density in each section, and neovascularization, expressed as a percentage, was determined as the absolute value of the total vascular density derived from factor VIII-rag-stained sections minus the vascular density derived from CD31-stained sections. RESULTS: Mean vascular density of thyroid gland carcinomas derived from CD31-stained sections was significantly greater than density derived from factor VII I-rag-stained sections. This incremental difference was presumed to represent degree of neovascularization. However, significant differences were not detected between vascular densities derived from CD31 and factor VIII-rag-stained sections for either normal thyroid gland tissue or thyroid gland adenomas. No significant correlations were found between vascular density in thyroid gland carcinomas and survival time following surgery. CONCLUSION AND CLINICAL RELEVANCE: A computer-assisted image analysis method was developed for quantifying neovascularization in thyroid gland tumors of dogs. This method may allow identification of dogs with tumors that are most likely to respond to treatment with novel antiangiogenesis agents.     

Preoperative immunosuppressive therapy and surgery as a treatment for anal furunculosis

OBJECTIVES: To evaluate the efficacy of combining preoperative immunosuppressive therapy with surgical excision for treatment of anal furunculosis (AF) in dogs. STUDY DESIGN: Retrospective study. ANIMALS: Dogs (n=25) with stages 1-4 AF. METHODS: Preoperative immunosuppressive therapy was either cyclosporine A (CyA) alone or in combination with ketoconazole (Group 1; n=18), or azathioprine combined with prednisolone (Group 2; n=7). Surgical excision of residual draining tracts, cryptectomy, and anal sacculectomy were performed. Only dogs with postoperative clinical follow-up exceeding 9 months were retained for the study. RESULTS: Both immunosuppressive protocols were effective in reducing progression of AF. Subsequent draining tracts excision, cryptectomy, and anal sacculectomy were bilateral (12 dogs) or unilateral (13 dogs of which 4 had bilateral anal sacculectomy). Postoperative recovery was uneventful, except for 2 dogs that had wound breakdown. Recurrence was not observed in any of the dogs that had bilateral surgical excision and or in 9 dogs that had unilateral excision. CONCLUSION: Preoperative immunosuppressive therapy, combined with bilateral surgical resection of affected tissue consistently, resulted in resolution of AF. Four dogs that had recurrence had unilateral excision despite initial bilateral involvement, suggesting that all diseased tissue should be excised. CLINICAL RELEVANCE: These preliminary results suggest that immunosuppressive therapy before surgical excision for AF yields minimizes recurrence in dogs.     

Cranial mediastinal carcinomas in nine dogs*

Nine dogs were diagnosed with cranial mediastinal carcinomas. Based on histological and immunohistochemical analysis, four dogs were diagnosed with ectopic follicular cell thyroid carcinomas, one dog with ectopic medullary cell thyroid carcinoma, two dogs with neuroendocrine carcinomas and two dogs with anaplastic carcinomas. Clinical signs and physical examination findings were associated with a space‐occupying mass, although one dog was diagnosed with functional hyperthyroidism. Surgical resection was attempted in eight dogs. The cranial mediastinal mass was invasive either into the heart or into the cranial vena cava in three dogs. Resection was complete in six dogs and unresectable in two dogs. All dogs survived surgery, but four dogs developed pulmonary thromboembolism and two dogs died of respiratory complications postoperatively. Adjunctive therapies included pre‐operative radiation therapy (n = 1) and postoperative chemotherapy (n = 3). Three dogs had metastasis at the time of diagnosis, but none developed metastasis following surgery. The overall median survival time was 243 days. Local invasion, pleural effusion and metastasis did not have a negative impact on survival time in this small case series.     

INCIDENTAL AND NONINCIDENTAL CANINE THYROID TUMORS ASSESSED BY MULTIDETECTOR ROW COMPUTED TOMOGRAPHY: A SINGLE‐CENTRE CROSS SECTIONAL STUDY IN 4520 DOGS

Thyroid nodules are common in dogs and are increasingly likely to be detected with the increased use of advanced imaging modalities. An unsuspected, nonpalpable, asymptomatic lesion, defined as a thyroid incidentaloma, may be discovered on an imaging study unrelated to the thyroid gland. The objective of this single‐center cross‐sectional study was to assess the prevalence and computed tomography (CT) characteristics of incidental and nonincidental thyroid tumors in a large population of dogs, using prospective recruitment of patients undergoing CT examination for various reasons during the period of 2005–2015. Unilateral or bilateral thyroid masses were detected in 96/4520 dogs (prevalence, 2.12%; 95% confidence interval [CI], 1.70–2.54%). Seventy‐nine (82.3%) lesions were malignant and 17 (17.7%) were benign. Masses were discovered incidentally in 34/96 dogs (overall prevalence of incidentaloma, 0.76%; 95% CI, 0.51–1.02), and 24 (70.6%) of these 34 masses were thyroid carcinomas. Among the CT variables assessed, mineralization, vascular invasion, and tissue invasion were detected only in malignant tumors. Intratumoral vascularization was significantly associated with the presence of thyroid malignancy (P < 0.001). Although incidental thyroid nodules in dogs are relatively rare, they are often malignant. Findings indicated that the neck should be thoroughly assessed in middle‐aged and old patients undergoing body CT for various reasons. Thyroid nodules detected incidentally on CT should be sampled to avoid missing thyroid cancer.     

A Comparison of Medullary Thyroid Carcinoma and Thyroid Adenocarcinoma in Dogs: A Retrospective Study of 38 Cases

The medical records of 38 dogs with thyroid neoplasia that were treated by surgical excision of the tumor, or had an incisional biopsy performed as a diagnostic procedure, were reviewed. Of the 38 dogs, 21 (55%) had resectable tumors, whereas 17 (45%) had an incisional biopsy as the tumors were nonresectable. All dogs had an initial diagnosis of thyroid carcinoma. The type of carcinoma was confirmed in 33 dogs by histological and immunohistochemical examination. Twelve dogs (36%) had medullary thyroid carcinoma, and 21 dogs (64%) had thyroid adenocarcinoma. Of the 12 dogs with medullary thyroid carcinoma, 10 (83%) had resectable tumors. Of the 10, three (30%) had at least a 1-year survival. None had radiographic evidence of metastasis at the time of surgery. Of the 21 dogs with thyroid adenocarcinoma, 11 (52%) had resectable tumors. Of the 11 dogs, five (45%) had at least a 1-year survival. Three dogs had radiographic evidence of metastasis at the time of surgery. Of 10 dogs with nonresectable thyroid adenocarcinoma, two dogs (20%) had at least a 1-year survival. In the dogs in this study, medullary thyroid carcinoma was more prevalent than previously reported. Most of the medullary thyroid carcinomas were well circumscribed and resectable. Medullary thyroid carcinoma may possess gross and histological characteristics of a less malignant nature when compared with other thyroid carcinomas.     

Surgical therapy of canine nasal tumors: A retrospective study (1982-1986)

The results of surgical therapy in 15 dogs with histologically confirmed nasal tumors were analyzed retrospectively and compared to previous reports. Median survival time for all dogs was seven months. When adjusted for nontumor-related deaths, median survival increased to nine months. These values are two to three times longer than previous reports. To determine possible prognostic indicators, tumor stage, location, and histological type were compared to survival time. Dogs with unilateral nasal tumors had a median survival of 11 months, as compared to three months for dogs with bilateral tumors (p = 0.005). Tumor stage and histological type were not significant factors in comparing survival times.     

Clinical and pathologic features of thyroid tumors in 26 dogs

Thyroid tumors were diagnosed in 26 dogs between 1977 and 1984. A total of 23 of the 26 tumors were carcinomas, and 3, detected as incidental findings at necropsy, were adenomas. The median patient age was 9.5 years. Dogs of the Beagle breed were affected most commonly (5 dogs). The most common physical abnormalities in carcinoma patients were cervical swelling, dyspnea, and coughing. A total of 25 of 26 dogs were clinically euthyroid. Aspiration cytology provided diagnostic information in 8 of 17 cases. In dogs with thyroid carcinoma, a cervical soft tissue lesion was identified consistently by use of radiography and scintigraphy with sodium pertechnetate. Pulmonary metastases were detected radiographically in 8 of 21 dogs with thyroid carcinoma. Thoracic nuclear imaging confirmed the radiographic findings in 11 of 14 dogs. Surgical excision of the thyroid mass was the primary treatment for 17 dogs with carcinoma. Eight dogs died within 2 years (median, 7 months) of surgery because of primary tumor regrowth or metastases. Four dogs were alive at a range of 3 to 48 months after surgery, and 4 dogs died from unrelated causes. Necropsy of 7 dogs with thyroid carcinoma revealed neoplastic infiltration of the cervical blood vessels and pulmonary metastases in each dog. The most common histologic patterns of thyroid carcinoma were solid or compact cellular (11 dogs) and mixed solid-follicular tumors (8 dogs). Dogs with a solid carcinoma had a median survival time of 10.5 months (6 dogs), and dogs with a mixed solid-follicular tumor had a median survival time of 8 months (3 dogs).     

Diagnosis and treatment of arthrosis of cervical articular facet joints in Scottish Deerhounds: 9 cases (1998-2002)

OBJECTIVE: To determine diagnostic features and efficacy of treatment of arthrosis of the cervical articular facet joints between C2 and C3 in Scottish Deerhounds. DESIGN: Retrospective study. ANIMALS: 9 client-owned dogs. PROCEDURE: Medical records of affected dogs were reviewed. Diagnosis was confirmed by results of clinical examination (signs of severe pain from unilateral or bilateral flexion of the cervical vertebral column), radiography, myelography, and computed tomography. Treatment consisted of fluoroscopy-guided intra-articular injection of corticosteroids and lidocaine. RESULTS: Unilateral or bilateral arthrosis of the cervical facet joints between C2 and C3 was detected in all dogs. In 7 dogs, signs of pain were elicited by flexion of the side of the neck in which affected joints were detected radiographically. Two dogs had signs of pain during right lateral flexion, although bilateral lesions were detected. Five dogs had unilateral lesions, and 4 dogs had bilateral lesions; sclerosis and hypertrophy of the articular process were common. Two dogs had bridging of the articular space. Use of computed tomography confirmed the diagnosis. Myelography did not reveal abnormalities of the spinal cord or canal. After treatment, 8 dogs had rapid marked improvement of clinical signs, and 7 dogs remained free of clinical signs for > 4 months. CONCLUSIONS AND CLINICAL RELEVANCE: Arthrosis of the cervical facet joints in Scottish Deerhounds is a severely painful condition for which conventional radiography is a useful screening test. Intra-articular administration of corticosteroids and anesthetic is efficacious, long-lasting, and minimally invasive.     

犬乳腺肿瘤手术治疗及其预后的调查

本研究采用单个乳腺切除、区域乳腺切除、单侧乳腺切除对临床31例犬乳腺肿瘤病例进行手术治疗,调查不同手术方法及肿瘤质量对良性、恶性乳腺肿瘤术后预后的影响。结果显示,犬乳腺肿瘤的大小与其预后相关,随着犬瘤体质重的增加,其术后预后不良愈加明显,复发率、死亡率呈上升趋势;区域乳腺摘除术或乳腺完全根除术对乳腺肿瘤患犬的预后有一定影响。     

Ultrasonographic characteristics of both adrenal glands in 15 dogs with functional adrenocortical tumors.

Ultrasonographic examination of both adrenal glands was performed in 15 dogs with functional adrenocortical tumors (FAT). Bilateral adrenal tumors were diagnosed in three of 15 dogs, and unilateral tumors were diagnosed in 12 of 15 dogs. Adrenal tumors were characterized by adrenal gland enlargement with loss of the normal shape and parenchymal structure. The contralateral adrenal gland could be imaged in all dogs with unilateral tumors. Based on size, shape, and parenchymal structure, the contralateral adrenal gland was similar to adrenal glands of normal dogs. The results of this study show that: 1) both adrenal glands should be imaged routinely in dogs with hyperadrenocorticism; 2) bilateral adrenocortical tumors seem to be more frequent than previously assumed; 3) one normal adrenal gland does not exclude the existence of a contralateral FAT; and 4) the functional atrophy of the contralateral adrenal gland in dogs with FAT may not be apparent ultrasonographically.     

Surgical treatment and long-term outcome of ferrets with bilateral adrenal tumors or adrenal hyperplasia: 56 cases (1994-1997).

OBJECTIVE: To determine signalment, clinical signs, concurrent diseases, response to surgical treatment, and long-term outcome of ferrets with bilateral adrenal tumors or adrenal hyperplasia. DESIGN: Retrospective study. ANIMALS: 56 ferrets with bilateral adrenal tumors or adrenal hyperplasia confirmed histologically following subtotal bilateral adrenalectomy. PROCEDURE: Medical records of all ferrets with bilateral adrenal tumors or hyperplasia examined between 1994 and 1997 were reviewed. Ferrets underwent a subtotal bilateral adrenalectomy or a unilateral adrenalectomy initially, followed by a unilateral subtotal adrenalectomy when tumors or hyperplasia later developed on the contralateral adrenal gland. A long-term follow-up of a minimum of 18 months after final adrenal gland surgery was obtained by examination of medical records and follow-up telephone conversations. RESULTS: Clinical signs of hyperadrenocorticism included bilaterally symmetric alopecia, return to male sexual behavior in castrated male ferrets, or swollen vulva in spayed female ferrets. Surgical treatment of bilateral adrenal disease by subtotal bilateral adrenalectomy (or unilateral adrenalectomy followed by contralateral unilateral subtotal adrenalectomy) was effective with a mortality rate of < 2%. Only 3 (5%) ferrets required glucocorticoid or mineralocorticoid replacement following subtotal bilateral adrenalectomy. Recurrence after bilateral adrenalectomy was 15% with a mean long-term follow-up period of 30 months. CONCLUSIONS AND CLINICAL RELEVANCE: Bilaterally symmetric alopecia, return to male sexual behavior in castrated male ferrets, or swollen vulva in spayed female ferrets are indicative of adrenal tumors or adrenal hyperplasia in ferrets. Surgical treatment of bilateral adrenal disease by subtotal bilateral adrenalectomy is effective, with a low rate of complications and postoperative recurrence rate.     

DEFINITIVE RADIATION THERAPY FOR INFILTRATIVE THYROID CARCINOMA IN DOGS

The medical records of eight dogs with histopathologically confirmed infiltrative thyroid carcinoma treated with external beam radiation were reviewed and a retrospective analysis of survival and local tumor control were performed. The dogs received a definitive radiotherapy protocol of 46.8-48 Gray. All dogs had a reduction in tumor size to a clinically undetectable level on follow up examinations. Kaplan-Meier analysis indicated a median survival time of 24.5 months. Pulmonary metastasis was detected in three dogs and one of these dogs had concurrent bone metastasis. One dog had bone metastasis alone. Two dogs were alive at the censor. This study suggests that fractionated, definitive radiation therapy using multiple, moderate doses of radiation is an effective treatment for local control of invasive thyroid carcinoma in dogs.