Outcomes for dogs with functional thyroid tumors treated by surgical excision alone

Abstract

OBJECTIVE To describe clinical findings and survival times for dogs with functional thyroid tumors treated with surgery alone and investigate potential prognostic factors for outcome in these patients. ANIMALS 27 client-owned dogs. PROCEDURES Medical records of 9 institutions were reviewed to identify dogs with hyperthyroidism secondary to thyroid neoplasia that were treated with surgery alone between 2005 and 2015. Data collected included signalment, hematologic and physical examination findings, tumor staging results, time from diagnosis to treatment, surgical procedure performed, histologic findings, evidence of recurrence or metastatic disease, and date of death or last follow-up. Median survival time and 1-, 2-, and 3-year survival rates were assessed by Kaplan-Meier analysis. Associations between variables of interest and the outcome of death were assessed with Cox proportional hazards models. RESULTS Dogs from 8 institutions met inclusion criteria. Median age at diagnosis was 10 years (range, 8 to 13 years). Golden Retrievers and Labrador Retrievers were commonly represented (5 dogs each). Polyuria with polydipsia (15/27 [56%]) and weight loss (12 [44%]) were the most common clinical signs; 2 dogs without clinical signs had hyperthyroidism identified by routine hematologic analysis. One dog had metastatic disease at the time of diagnosis. Most tumors (23/27 [85%]) were malignant. Estimated median survival time was 1,072 days. No significant prognostic factors were identified. CONCLUSIONS AND CLINICAL RELEVANCE Dogs with resectable functional thyroid tumors had a good prognosis with surgical excision alone. Survival times for these dogs were similar to those in previous studies that included dogs with nonfunctional thyroid tumors.

To map or not to map the cN0 neck: Impact of sentinel lymph node biopsy in canine head and neck tumours

“…This consideration is consistent with the prolonged survival times previously reported for surgically resected early-stage thyroid tumors and with metastases being more frequently detected during necroscopy (60-80%) than at the time of treatment (7-38%). 37,38 In the study population, at least one "hot" node was extirpated in each dog, and only 7/34 hot nodes were not blue stained, confirming the correspondence between RC and blue dye. 9,30 In human medicine adverse reactions to methylene blue injection are not rare, and some authors suggest the omission of blue dye owing the high detection rates reported with use of the radiopharmaceutical alone.…”

“…Reported rates of nodal metastases for thyroid carcinomas varies significantly among studies (7%-38%), probably due to the lack of standardization in staging modalities and inclusion of early to advance stage tumours. [36][37][38] Recently, metastases to surgically excised deep cervical lymph nodes have been described in 45% of dogs with thyroid carcinoma, several of which had negative prognostic factors such has bilateral tumours, lymphatic or vascular invasion and capsular invasion. 39 Conversely, the four thyroid tumours included in the present study were early-stage and no negative prognostic factors were recognized, except for the ectopic location of one thyroid carcinoma.…”

Response of canine thyroid carcinomas to radioiodine

“…2,[6][7][8] Surgical excision is the treatment of choice for non-metastatic, mobile tumours; however, only approximately 25%-50% of cases are amenable to surgery, due to large tumour size and fixation to underlying tissues. 5,[9][10][11] Treatment with external beam radiation therapy (RT) has been reported for non-resectable, advanced stage thyroid carcinomas. 9,[12][13][14] Medical treatment for non-resectable tumours using platinum-based chemotherapy or doxorubicin results in variable outcomes, with 30%-50% tumours showing some response.…”

“…Surgical excision is the treatment of choice for non‐metastatic, mobile tumours; however, only approximately 25%–50% of cases are amenable to surgery, due to large tumour size and fixation to underlying tissues 5,9–11 . Treatment with external beam radiation therapy (RT) has been reported for non‐resectable, advanced stage thyroid carcinomas 9,12–14 .…”

Use of oral chemotherapeutic agent, chlorambucil, as palliative treatment of thryoid adenocarcinoma in a golden‐headed lion tamarin (Leontopithecus chrysomelas)

“…1,2 Thyroid adenocarcinomas are considered malignant and have historically represented most of the thyroid neoplasms in domestic canines, but a few cases have been documented in nondomestic cats, a bald eagle, and transgenic mice. [3][4][5][6][7] No known reports of clinical management with oral chemotherapeutic agents in nonhuman primates have been published. Many chemotherapeutic agents require intravenous administration, which can be challenging to administer in callitrichid species without anesthesia.…”