Complications and outcomes associated with unilateral thyroidectomy in dogs with naturally occurring thyroid tumors: 156 cases (2003-2015)

Effect of Changes in Canine Thyroid Cancer Terminology on Caregiver Anxiety Levels and Treatment Preferences in a Scenario-Based Study

In human medicine, the choice of medical terminology influences patients' choice of management options and associated anxiety levels in relation to their diagnoses. The objective of this study was to determine the association between canine caregiver's treatment choices and anxiety levels when papillary thyroid cancer is described with or without the term cancer. This randomised cross-sectional study surveyed 683 people over 18 years old over 8.5 months. Respondents ranked their treatment preference (total thyroidectomy, active surveillance, medical therapy, or radiation therapy) following a scenario-based diagnosis of papillary thyroid cancer (PTC), thyroid papillary lesion (TPL) or abnormal cells (AC) in their canine pet. Respondents stated their level of anxiety associated with the diagnosis and treatment choice. Of 683 respondents, 622 (91.7%) were female. When presented with a diagnosis of PTC, TPL or AC, 78.1%, 34.2% and 59.3% of participants, respectively, reported being anxious or very anxious about this diagnosis (p < 0.01). Surgery was chosen as a first-choice treatment for PTC, TPL and AC by 71.8%, 39.8% and 53.8% of respondents, respectively, whereas active surveillance was chosen as a first-choice treatment by 24.5%, 57.5% and 43.9% of respondents, respectively. There was a statistically significant difference in first-choice treatment selection (p < 0.01) and anxiety levels related to treatment (p < 0.01) between the three different terms. The terminology used when presenting caregivers with a diagnosis of PTC influences treatment choices and levels of anxiety.

A combination of pre- and intraoperative techniques identifies sentinel lymph nodes in dogs with thyroid carcinoma: A pilot study

OBJECTIVE

The aim of this study was to develop and describe pre- and intra-operative sentinel lymph node (SLN) mapping techniques in dogs with thyroid carcinoma.

STUDY DESIGN

A prospective, pilot clinical trial was performed.

ANIMALS

Six client-owned dogs with unilateral thyroid carcinoma and no overtly metastatic locoregional lymph nodes (LNs) were enrolled.

METHODS

All dogs underwent preoperative indirect computed tomography (CT)-lymphography (CTL) with peritumoral iohexol injection and intraoperative SLN mapping with peritumoral injection of a visible dye (methylene blue [MB]) and near-infrared (NIR) fluorescent dye (indocyanine green [ICG]). Subsequent LN extirpation and routine thyroidectomy were performed. All excised tissues were evaluated histologically.

RESULTS

Pre- and intra-operative SLN mapping identified at least one SLN in all dogs. A median of one SLN (range, 1-2) was identified on both CTL and intraoperative SLN mapping. Identified SLNs included medial retropharyngeal, cranial deep cervical, and superficial cervical LNs. Variability between pre- and intra-operative SLN findings occurred in 3/6 dogs. A median of two LNs (range, 1-3) were extirpated for each dog. Metastatic carcinoma was diagnosed in extirpated LNs in 2/6 dogs and 3/12 extirpated LNs.

CONCLUSION

In this pilot study, preoperative CTL and intraoperative MB and ICG/NIR allowed for identification of SLNs in dogs with thyroid carcinoma.

CLINICAL SIGNIFICANCE

Sentinel lymph nodes were identified and extirpated using the described techniques, with nodal metastasis identified in a subset of these dogs due to SLN mapping. Large-scale, powered studies are needed to accurately determine the incidence and prognostic significance of nodal metastasis identified by SLN mapping and extirpation in dogs with thyroid carcinoma.

Sodium iodide symporter immunolabelling as a predictor of clinical iodide uptake in canine thyroid carcinoma: A preliminary study

Thyroid follicular tumours may take up iodide via the sodium-iodide symporter. Knowledge of iodide uptake could then allow treatment with I-131 in dogs with high-risk tumours. The objective of this study was to determine the relationship between clinically detectable iodide uptake (as determined by scintigraphy and/or thyroxine concentrations) and sodium iodide symporter immunohistochemical labelling on histologically fixed thyroid tumours. Nineteen dogs were identified who were diagnosed with thyroid carcinoma and underwent surgery from November 2017 to July 2021. All had recorded thyroid hormone concentrations and were hyperthyroid and/or underwent preoperative nuclear imaging using planar scintigraphy (technetium-99m or I-123), or I-124 PET-CT. All dogs subsequently underwent surgery to remove the thyroid mass. Twenty-two tumours were submitted for histopathologic analysis immediately following surgery, which confirmed a diagnosis of thyroid carcinoma for each tumour. Images and/or thyroid hormone concentrations were reviewed for the included cases, and tumours were sorted into an avid/functional group (group 1) and a non-avid/functional group (group 2). The tumour tissues were re-examined histologically using sodium iodide symporter (NIS) immunohistochemistry (IHC). Group 1 contained 15 avid/functional tumours. Twelve of these tumours had membranous NIS IHC labelling. Group 2 contained 7 non-avid tumours. One of these tumours had membranous NIS IHC labelling. This resulted in an overall sensitivity and specificity for identification of avid/functional tumours with membranous NIS of 80.0% and 85.7%, respectively. NIS IHC may predict ion trapping in canine follicular thyroid tumours. Further studies using iodide-based imaging are warranted to better determine the clinical utility of this diagnostic modality.

Clinical outcomes of thyroid tumours with concurrent epithelial and mesenchymal components in 14 dogs (2006-2020)

Background

While rare, multiple individual case reports have described mixed thyroid tumours in dogs containing both epithelial and mesenchymal neoplastic components.

Objectives

In this retrospective case series, we describe the clinical presentation, treatment and outcome of 14 dogs of canine thyroid tumours with concurrent mesenchymal and epithelial neoplastic populations.

Methods

Fourteen cases were retrospectively abstracted from nine institutions. Histopathologic samples and reports were collected from 10/14 dogs and reviewed by a single board‐certified anatomic pathologist.

Results

All 14 dogs had curative‐intent surgery to remove the thyroid neoplasm. The most common surgery performed was a unilateral thyroidectomy (10/14 dogs). Postoperatively, systemic therapy was administered in eight dogs. Six dogs developed local recurrence with a median time to loco‐regional recurrence of 53 days. Ten dogs developed metastatic disease with the most common metastatic site being the lungs (6/10 dogs), with a median time to metastasis of 93 days. Ten dogs were euthanised due to locoregional or distant progression of their mixed thyroid neoplasm. The overall median survival time was 156 days (95%CI: 49–244). The median survival time for dogs treated with adjuvant therapy was 189 days (95%CI: 24–244), whereas dogs without adjuvant therapy had a median survival time of 156 days (95%CI: 35‐upper limit could not be calculated; p = 0.62).

Conclusion

The thyroid tumours with both mesenchymal and epithelial components in this small sample set were associated with a poor prognosis after surgical excision with or without adjunctive therapy.

Outcome and postoperative complications in 73 dogs with thyroid carcinoma with gross vascular invasion managed with thyroidectomy

Excellent outcomes have been reported following thyroidectomy for thyroid carcinoma in dogs, but outcomes for thyroid carcinomas with gross vascular invasion are poorly described. This study describes the clinical outcomes and complications in dogs with thyroid carcinomas with gross vascular invasion undergoing thyroidectomy. Medical records of dogs that underwent thyroidectomy between January 1st 2010 and December 31st 2019 were reviewed at 10 hospitals. Signalment, diagnostic data, primary and adjuvant treatments performed, and outcome were abstracted. Survival was calculated using Kaplan-Meier analysis. Multiple logistic regression was used to identify variables associated with disease-specific survival. Seventy-three dogs were included, of which 58 underwent unilateral thyroidectomy and 15 underwent bilateral thyroidectomy. Complications were reported in five dogs (three major, two minor; 6.8%) intraoperatively and 12 dogs (two major leading to death, 10 minor; 16.4%) postoperatively. Seven (9.6%) dogs developed locoregional recurrence at a median of 238 days postoperatively (range: 15-730 days). Distant metastasis was suspected or confirmed in nine dogs (12.3%) at a median of 375 days postoperatively (range: 50-890 days). Twenty-seven dogs (37%) received adjuvant therapy (chemotherapy: n = 21; radiotherapy: n = 6). Thirty-nine dogs were euthanized or died, with 20 deaths related to disease (n = 10) or of unknown cause (n = 10), 19 due to unrelated causes, and nine lost to follow-up. Median overall and disease-specific survival were 621 days and not reached respectively. One-year disease-specific survival rate was 82.5%. No variables were associated with disease-specific survival in our dataset. Surgery may be considered for loco-regional therapy in dogs with thyroid carcinoma with gross vascular invasion.

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

Tumour stage is a prognostic indicator for canine malignant head and neck tumours (MHNT). However, consensus is lacking on nodal staging in the absence of clinically apparent nodal disease (cN0 neck). This prospective observational study aims to determine the diagnostic accuracy of radiopharmaceutical and blue dye for sentinel lymph node biopsy (SLNB), to assess the correspondence between sentinel lymph node (SLN) and clinically expected regional lymph node (RLN) and the impact on staging of the procedure in dogs with MHNT and cN0 neck. Twenty-three dogs with MHNT and cN0 neck underwent tumour excision and SLNB guided by preoperative lymphoscintigraphy and intraoperative gamma-probe and blue dye. Diagnostic performances and detection rate were calculated. Correspondence between SLN and RLN, number of nodes excised, histopathological status of the SLN and complications related to the procedure were recorded. The mapping technique identified at least one SLN in 19/23 dogs, with a detection rate of 83%. The SLN did not correspond to the RLN in 52% of dogs. Multiple nodes were removed in 61% of dogs. At histopathology, eight (42%) dogs had SLN+, of which four differed from the RLN. Only minor self-limiting complications occurred in five (22%) dogs. Radiopharmaceutical and blue dye guidance is accurate (sensitivity 88.9%; specificity 100%) for SLNB in dogs with MHNT and cN0 and allowed the extirpation of unpredictable and/or multiple SLN with minimal morbidity. Incorporation of SLNB in the management of MHNT is desirable to correctly stage the cN0 neck, owing the unpredictability of the lymphatic drainage.

Preoperative autologous blood donation and transfusion in dogs undergoing elective surgical oncology procedures with high risk of hemorrhage

OBJECTIVE

To describe preoperative autologous blood donation (PABD) and transfusion in dogs undergoing elective surgical oncology procedures with a high risk of intraoperative hemorrhage.

STUDY DESIGN

Prospective study.

ANIMALS

Twelve dogs.

METHODS

Dogs undergoing surgical oncology procedures associated with a high risk of hemorrhage were enrolled. Blood was collected a minimum of 6 days before surgery and separated into fresh frozen plasma (FFP) and packed red blood cells (pRBC). Dogs received FFP at the start of surgery and pRBC intraoperatively when hemorrhage ensued. The mean packed cell volume/total solids (PCV/TS) were calculated on the day of PABD preoperatively, immediately postoperatively, and 24 hours after transfusion. The dogs were monitored for transfusion-related adverse reactions, including hyperthermia, hypotension, tachycardia, bradycardia, pale mucous membranes, prolonged capillary refill time, or tachypnea/dyspnea.

RESULTS

Dogs enrolled in the study underwent mandibulectomy, maxillectomy, chest wall resection, and liver lobectomy. Ten of the 12 dogs that underwent PABD received autologous transfusion at first signs of hemorrhage intraoperatively. Iatrogenic anemia was noted in two dogs (PCV 30% and 31%). The mean PCV/TS levels on the day of blood collection, preoperatively, immediately postoperatively (after transfusion), and 24 hours posttransfusion were 45.1%/7.1 g/dL, 42.2%/6.73 g/dL, 33.2%/5.42 g/dL, and 36.5%/5.65 g/dL, respectively. No dog developed transfusion-related complications.

CONCLUSION

Preoperative autologous blood donation was well tolerated and led to uneventful autologous transfusion in 10 of 12 dogs.

CLINICAL SIGNIFICANCE

Preoperative autologous blood donation and autologous transfusion are feasible for dogs undergoing elective surgical procedures with a high risk of hemorrhage.

Metastasis to ipsilateral medial retropharyngeal and deep cervical lymph nodes in 22 dogs with thyroid carcinoma

OBJECTIVE

To determine the rate of nodal metastasis to the medial retropharyngeal (MRP) and deep cervical lymph nodes in dogs surgically treated for thyroid carcinoma.

STUDY DESIGN

Retrospective study.

ANIMALS

Twenty-two client-owned dogs.

METHODS

Medical records between July 2015 and October 2019 at the Universities of Missouri and Florida were reviewed. Dogs that underwent thyroidectomy with concurrent elective MRP lymphadenectomy ± deep cervical lymphadenectomy were included. Tumor site, preoperative staging, and histopathological findings were recorded.

RESULTS

Twenty-two dogs with 26 total thyroid carcinomas were included. Primary tumors were lateralized in 19 dogs, bilateral in two dogs, and bilateral and midline ectopic in one dog. All dogs underwent ipsilateral MRP resection, including bilateral resection in dogs with bilateral tumors. Three contralateral MRP lymph nodes were excised from dogs with unilateral carcinomas. Four deep cervical lymph nodes and one superficial cervical lymph node were excised. Metastases were identified in 14 lymph nodes in 10 of 22 (45%) dogs. All four excised deep cervical lymph nodes and one contralateral MRP lymph node were identified as metastatic. Size of deposit could be classified in 13 of 14 metastatic lymph nodes. Macrometastasis was detected in seven lymph nodes, micrometastasis was detected in one node, and isolated tumor cells were detected in five lymph nodes.

CONCLUSION

Regional metastasis was common within the lymph nodes sampled in this population of dogs with thyroid carcinoma.

CLINICAL SIGNIFICANCE

These results provide evidence to justify further exploration of a larger population to verify the rate of regional metastasis and determine the prognostic impact of nodal metastasis.