Pulmonary lymph node charting in normal dogs with blue dye and scintigraphic lymphatic mapping

Evaluation of mediastinoscopy for cranial mediastinal and tracheobronchial lymphadenectomy in canine cadavers

OBJECTIVE

To report technical feasibility and describe procedural details of a novel single incision minimally invasive approach to the mediastinum in cadaver dogs.

STUDY DESIGN

Cadaveric study.

ANIMALS

Large breed (25-40 kg) cadaver dogs (n = 10).

METHODS

Three of 10 cadavers were used for preliminary technique development without data recording. Cadaver specimens underwent pre- and postoperative thoracic computed tomographic scans. Seven dogs were placed in dorsal recumbency and mediastinoscopy was performed via a SILS port placed cranial to the thoracic inlet with CO2 insufflation of the mediastinum at 2-4 mmHg. Retrieval of all CT and visually identified mediastinal lymph nodes (LN) was attempted; endoscopic compartmental and individual LN dissection times and subjective operative challenges were recorded. Procedural success scores for visualization and dissection as well as NASA-task force index scores were recorded per lymph node, per cadaver.

RESULTS

Median time required for initial approach including SILS placement was 5 min (range 5-10 min). Individual LN retrieval times ranged from 2 to 32 min. Mediastinoscopic retrieval of LNs was most commonly successful for the left tracheobronchial LN (7/7), followed by the right tracheobronchial LN (4/7), the left and right sternal LNs (3/7 each), and the cranial mediastinal LNs (1/7). Post-procedure pleural gas was identified on CT in 4/7 cadavers.

CONCLUSIONS

Mediastinoscopy as reported was feasible in large breed canine cadavers and retrieval or cup biopsy of a variety of lymph nodes is possible from the described approach. Application in living animals and its associated challenges should be further investigated.

CLINICAL SIGNIFICANCE

Mediastinoscopy may provide a novel minimally invasive approach to the evaluation and oncologic staging of the cranial mediastinum in dogs.

Evaluation of Surgical Aid of Methylene Blue in Addition to Intraoperative Gamma Probe for Sentinel Lymph Node Extirpation in 116 Canine Mast Cell Tumors (2017-2022)

Methylene Blue (MB) is combined with radiopharmaceutical for intraoperative sentinel lymph node (SLN) mapping, but its role during SLN extirpation has not been investigated yet in veterinary medicine. The aim of this study was to assess whether MB increased surgical detection of SLN beyond the use of intraoperative gamma-probe (IGP) alone in clinically node-negative dogs with mast cell tumors (MCTs) following the detection of sentinel lymphocentrums (SLCs) via preoperative planar lymphoscintigraphy. Dogs enrolled underwent MCT excision and SLC exploration guided by both MB and IGP. Data recorded for each SLN were staining (blue/non-blue), radioactivity (hot/non-hot), and histopathological status (HN0-1 vs. HN2-3). A total of 103 dogs bearing 80 cutaneous, 35 subcutaneous, and 1 mucocutaneous MCTs were included; 140 SLCs were explored, for a total of 196 SLNs removed. Associating MB with IGP raised the SLNs detection rate from 90% to 95%. A total of 44% of SLNs were metastatic: 86% were blue/hot, 7% were only blue, 5% were only hot, and 2% were non-blue/non-hot. All HN3 SLNs were hot. Combining MB with IGP can increase the rate of SLN detection in dogs with MCTs; nonetheless, all lymph nodes identified during dissection should be removed, as they might be unstained but metastatic.

Intraoral approach for zygomatic sialoadenectomy in dogs: An anatomical study and three clinical cases

OBJECTIVE

To describe an intraoral approach (IOA) for zygomatic sialadenectomy in dogs and to compare this surgical approach to a modified lateral orbitotomy approach (LOA).

STUDY DESIGN

Cadaveric study and short case series.

SAMPLE POPULATION

Ten canine cadavers and three dogs with clinical disease.

METHODS

Bilateral zygomatic sialoadenectomies were performed in six mesocephalic, two brachycephalic and two dolichocephalic cadavers, randomly assigned to IOA on one side and LOA on the contralateral side. Duration of surgery, ease of surgical stage scores (rated on 5-point Likert scale) and completeness of gland removal were recorded. Additionally, IOA was performed in three dogs with zygomatic salivary gland (ZSG) disease.

RESULTS

Removal of the ZSG was complete in 8/10 and 10/10 dogs using the IOA and LOA, respectively. Surgery was faster with IOA (42.0 min; 33.5-49.6 min) than LOA (65.7 min; 54.9-76.4 min, p = .005). Ease of removal did not differ between approaches (p = .091). Diseased ZSGs were successfully removed in three dogs without intra- or short-term postoperative complications.

CONCLUSIONS

The intraoral approach described here was technically equally challenging but faster than the LOA. Its clinical use led to an uneventful surgery with excellent short-term outcome in three dogs.

CLINICAL RELEVANCE

The IOA provides an alternative approach for zygomatic sialoadenectomy in dogs with ZSG disease.

Klinisch-pathologische Befunde, postoperative Überlebenszeiten und prognostische Faktoren bei Hunden mit primären Lungenkarzinomen

Einleitung Primäre Karzinome der Lunge (PLK) beim Hund sind selten, ihre Behandlung erfolgt chirurgisch. Ziel dieser Studie war die Untersuchung klinisch-pathologischer Befunde, postoperativer medianer Überlebenszeiten (mÜZ) und prognostischer Faktoren.

Material und Methoden Retrospektive Auswertung von 61 Hunden mit 62 PLK, die zwischen 2007 und 2017 chirurgisch behandelt wurden. Die statistische Auswertung erfolgte mittels Kaplan-Meier und Logrank Methoden.

Ergebnisse Von 62 PLKs lagen 35 (56 %) peripher im Lungenlappen, 21 (34 %) hilusnah und 6 (10 %) betrafen den gesamten Lungenlappen. In 49 Fällen lagen differenzierte Adenokarzinome vor; niedrig differenzierte bzw. anaplastische Karzinome (n = 10) und Plattenepithelkarzinome (n = 2) waren deutlich seltener. Eine Prädisposition für bestimmte Lungenlappen war nicht nachzuweisen. Dreizehn (21 %) Patienten zeigten keine und 10 (16 %) nur unspezifische, nicht auf den Respirationstrakt hinweisende Symptome. Insgesamt zeigten 48 (79 %) Hunde klinische Symptome wie Husten, Dyspnoe, Lethargie, Gewichtsverlust, Leistungsschwäche, Erbrechen und/oder Fieber. Die tracheobronchialen Lymphknoten (TBLN) waren in 9 von 51 untersuchten Fällen histologisch positiv für Metastasierung (N1) und negativ (N0) in 42 Fällen (nicht untersucht n = 10). Daten zum Langzeitverlauf waren für 50 Patienten verfügbar. Prognostisch relevante Variablen waren Lymphknotenmetastasierung in die TBLN (mÜZ: N1 41 Tage, N0 570 Tage; p < 0,01), Lungenmetastasen (mÜZ: M1 125 Tage, M0 630 Tage; p < 0,01), histologischer Subtyp (mÜZ: differenzierte Karzinome 620 Tage; andere Karzinome 135 Tage; p < 0,01), Tumordurchmesser größer als 3 cm (mÜZ < 3 cm 1155 Tage, ≥ 3 cm 330 Tage; p = 0,02) und Tumorlokalisation (mÜZ: hilusnah 330 Tage, peripher 650 Tage; p = 0,04).

Schlussfolgerung Beim PLK sind TBLN Status, Organmetastasen, Tumorlokalisation, histologischer Subtyp und Tumorgröße prognostisch relevante Kriterien. Hunde ohne prognostisch negative Faktoren können lange Überlebenszeiten aufweisen. In mehr als einem Drittel der Fälle bleiben die Tumoren asymptomatisch (21 %) bzw. ohne respirationstraktspezifische (16 %) Symptome.

Quantitative and Semi-quantitative Methods for Assessing the Degree of Methylene Blue Staining in Sentinel Lymph Nodes in Dogs

Background: To develop a digital algorithm for quantitative assessment of surface methylene blue staining in whole lymph nodes and validate a semi-quantitative visual scoring method for patient-side use.

Methods: Lymph nodes from canine patients with spontaneous tumors undergoing sentinel lymph node mapping were prospectively assessed ex vivo and photographed. Using an open-source computer-based imaging software, an algorithm was developed for quantification of staining based on a signal-to-background ratio. Next, two blinded observers evaluated images and assigned a semi-quantitative visual score based on surface staining (0—no blue stain, 1−1–50% stained, and 2−51–100% stained) and those results were compared to the established quantitative standard.

Results: Forty-three lymph nodes were included. Image analysis successfully quantified blue staining and differentiated from normal lymph node tissue in all cases. Agreement between observers using the Kappa coefficient demonstrated strong agreement (k = 0.8581, p < 0.0001) between semi-quantitative visual scoring and image analysis. There was substantial interobserver and intraobserver agreement for the scoring system (k = 0.7340, p < 0.0001 and k = 0.8983, p < 0.0001, respectively).

Conclusion: A digital algorithm using an open-source software was simple and straightforward to use for quantification of blue staining. The use of a semi-quantitative visual scoring system shows promise for a simple, objective, repeatable assessment of methylene blue staining at the time of surgery. This study demonstrates reliable and repeatable methods for blue staining quantification thereby providing a novel and objective reporting mechanism in scientific research involving sentinel lymph node mapping.

A Contemporary Retrospective Study of Survival in Dogs With Primary Lung Tumors: 40 Cases (2005-2017)

Objective: To report the median survival time in a contemporary cohort of dogs with primary lung tumors and intrathoracic nodal metastasis.

Design: Retrospective Case Series.

Animals (or sample): Dogs with primary lung tumors treated with lung lobectomy and lymph node biopsy.

Procedures: The medical record database at Colorado State University was queried for dogs with primary lung tumors from January 1, 2005 to December 31, 2017. Patients were identified for inclusion if they had lung lobectomy and an intrathoracic lymph node biopsy performed. The median survival time (MST) for lymph node positive (LN+) and negative dogs (LN–) was calculated as well as the MST in dogs that did or did not receive adjuvant chemotherapy. Differences were compared between groups with significance set at p < 0.05.

Results: The MST in LN+ dogs (n = 11) was 167 days which was not statistically different from LN– dogs (n = 29) at 456 days (p = 0.2407). No significant difference in the MST in LN+ dogs was identified between dogs that received adjuvant chemotherapy (n = 4; 110 days) and those that did not receive adjuvant chemotherapy (n = 6; 125 days) (p = 0.4409). There was no difference in survival time in LN– dogs receiving chemotherapy (n = 12; 335 days) as compared to those LN– dogs (n = 10) that did not receive adjuvant chemotherapy (258.5 days; p = 0.6475).

Conclusions and Clinical Relevance: The survival of primary pulmonary neoplasia in dogs with intrathoracic nodal metastasis is longer than previously reported in this contemporary cohort. Chemotherapy did not appear to improve survival in LN+ or LN– dogs. The combination of tumor size between 100 and 999 cm³ and positive lymph node status significantly reduced survival.

The use of methylene blue to assist with parotid sialadenectomy in dogs

INTRODUCTION

There is an important morbidity associated with parotidectomy. The most commonly reported permanent complication is facial nerve injury. Methylene blue staining has been used as an intra-operative tool to improve tissue visualisation and preserve facial nerve integrity.

OBJECTIVES

To describe the functionality and feasibility of the use of methylene blue for parotidectomy in dogs.

MATERIALS AND METHODS

Retrospective study included seven client-owned dogs that underwent parotidectomy after injection of methylene blue from 2016 to 2019 in a referral centre. Cross-sectional imaging was used to confirm parotid gland surgical disease and for staging purposes. All dogs underwent parotid resection and removal of the parotid duct after injection of methylene blue. Methylene blue was either administered via cannulation of the parotid duct or directly injected into the abnormal gland.

RESULTS

In all cases, the gland stained dark blue within seconds without any evident leakage. Complete parotid gland resection and removal of the parotid duct was achieved successfully in all dogs with a mean surgical time of 97 minutes. Subjectively, the staining was useful to identify innervation outside the coloured gland and facilitated dissection. No complications, including facial nerve injury, were recorded.

CLINICAL SIGNIFICANCE

Methylene blue staining for complete parotidectomy was feasible, rapid and easy in these dogs. It can be used as an indirect facial nerve identification technique, and can therefore facilitate dissection and possibly reduce the incidence of post-operative facial nerve paralysis.

Nonselective Lymph Node Dissection and Sentinel Lymph Node Mapping and Biopsy

Clinical staging is important for determining the extent of disease in animals with malignant cancers. The status of the lymph node will help determine whether adjuvant treatment is indicated. Historically, the regional anatomic lymph node has been sampled to determine the presence or absence of metastatic disease, but there is increasing evidence that the regional anatomic lymph node is often different to the sentinel lymph node. As a result, several sentinel lymph node mapping techniques have been described for more accurate clinical staging of oncologic patients.

Use of Minimally Invasive Surgery in the Diagnosis and Treatment of Cancer in Dogs and Cats

Surgical management of neoplastic disease is common in veterinary medicine. Minimally invasive surgery (MIS) has gained widespread acceptance by veterinary surgeons and is experiencing rapid growth and frequency of use. Many neoplastic diseases in the abdomen and thorax of dogs and cats can be treated as effectively with MIS as with traditional open surgery. Additionally, MIS allows for less invasive options for organ biopsy in cancer patients either for initial diagnosis or for staging to inform prognosis and treatment. Despite the recent increase in MIS, additional research is required to further characterize the benefits to oncology patients and to ensure that surgical oncologic principles and patient outcomes are not compromised by the use of MIS.

Sentinel lymph node mapping by near-infrared fluorescence imaging and contrast-enhanced ultrasound in healthy dogs

Sentinel lymph node (SLN) mapping is a valuable and crucial diagnostic procedure in staging malignancies. We compared two non-invasive techniques, near-infrared (NIR) fluorescence imaging and contrast-enhanced ultrasound (CEUS), to identify the SLNs in three superficial anatomical regions in an animal model. Six healthy laboratory dogs were included in a proof-of-concept trial. A NIR fluorescent dye (Indocyanine Green) and microbubbles (Sonovue) were consecutively injected subdermally in the Inguinal, axillary and popliteal region to map the SLNs. Transcutaneous NIR fluorescence imaging identified SLNs in 17 out of a total of 18 occasions. CEUS identified SLNs in all regions (18/18). Whereas NIR fluorescence imaging performed better in the visualization of the afferent lymphatic tract, CEUS demonstrated different filling patterns of the SLNs, a feature potentially critical for the concept of SLN mapping in cancer patients. Both NIR fluorescence imaging and CEUS are safe, non-invasive, practical and accurate methods to perform real-time transcutaneous SLN mapping with potential in a clinical setting.