Prospective assessment of canine thyroid cancer-part I: nodal metastatic rate and impact of nodal immunohistochemistry in 70 dogs.

OBJECTIVE: To determine the rate of nodal metastasis in dogs with thyroid cancer and evaluate whether immunohistochemistry (IHC) identifies additional metastases beyond evaluation with H&E. ANIMALS: 70 prospectively enrolled client-owned dogs with thyroid cancer managed with thyroidectomy. METHODS: Dogs underwent thyroidectomy with concurrent elective bilateral medial retropharyngeal (MRP) ± deep cervical lymphadenectomy. Thyroid tumors and associated lymph nodes were reviewed by a single board-certified pathologist. Immunohistochemistry was used for all primary tumors (thyroid transcription factor-1 and calcitonin) to support a diagnosis of follicular or medullary carcinoma. Lymph nodes without evidence of metastasis after H&E review were labeled with the antibody associated with the wider uptake in the primary tumor. RESULTS: 77 thyroid cancers were resected from the 70 dogs enrolled, including 61 (79.2%) follicular, 8 (10.7%) medullary, and 7 (9.3%) mixed follicular/medullary carcinomas, with 1 (1.3%) carcinosarcoma. Twelve dogs had evidence of nodal metastasis following H&E review. Occult micrometastasis was identified in 1 dog following nodal IHC, resulting in documented metastasis in 13 of 70 (18.6%) dogs. Metastasis was more common with medullary (5/8) and follicular/medullary carcinoma (3/7) than follicular carcinoma (5/61). All MRP metastases were ipsilateral (7/77 [9.1%]), without contralateral MRP metastases (0/62). Fourteen of 41 (34.1%) deep cervical lymph nodes were metastatic. CLINICAL RELEVANCE: Nodal metastasis was uncommon for follicular carcinoma but was seen in > 50% of dogs with thyroid cancer involving a medullary component. Routine nodal IHC appears to be low yield for thyroid carcinoma. Extirpation of ipsilateral MRP and identifiable deep cervical lymph nodes is recommended with thyroidectomy until detailed preoperative risk stratification becomes available.

Hypercoagulability based on thromboelastography is common in dogs undergoing adrenalectomy.

OBJECTIVE: Thromboelastography (TEG) is a whole blood assay that yields global assessment of hemostasis, as it evaluates clot time, strength, and kinematics of clot formation and lysis. The main objective was to describe preoperative TEG findings in dogs that had an adrenalectomy performed and, secondarily, to describe TEG findings in the dogs with or without hyperadrenocorticism (HAC). ANIMALS: 30 dogs that had preoperative TEG and adrenalectomy performed. METHODS: Medical records between 2018 and 2022 were reviewed. Signalment, diagnostic data, and perioperative treatment were abstracted. RESULTS: 53% (16/30) of the dogs were hypercoagulable, and none were hypocoagulable. Based on histopathology, 6 of 9 dogs with adenocarcinoma were hypercoagulable, 4 of 8 with pheochromocytoma were hypercoagulable, and 6 of 10 with adenoma were hypercoagulable. None of the 3 dogs with other histopathologic diagnoses or combinations of diagnoses (adrenocortical hyperplasia, poorly differentiated sarcoma, and both adrenocortical adenocarcinoma and pheochromocytoma) were hypercoagulable. Of the 14 dogs tested preoperatively for HAC, 4 of 8 HAC dogs were hypercoagulable and 2 of 6 non-HAC dogs were hypercoagulable. CLINICAL RELEVANCE: The present report describes for the first time TEG findings for dogs undergoing adrenalectomy and suggests that the majority of dogs with adrenal neoplasia are hypercoagulable based on TEG results.

Surgical approach and presence of preoperative pleural effusion impact thoracostomy tube usage in dogs and cats following thoracic surgery for suspected neoplasia.

OBJECTIVE: To assess factors associated with increased pleural fluid and air evacuation, longer duration of thoracostomy tube usage, and longer hospitalization in dogs and cats following surgery for thoracic neoplasms. ANIMALS: 62 dogs and 10 cats. METHODS: Medical records were reviewed for dogs and cats undergoing thoracic surgeries between August 1, 2019, and June 30, 2023, for resection of suspected neoplasia in which a thoracostomy tube was placed. Data collected included patient signalment, type of procedure performed, histologic diagnosis of the primary mass removed, volume of fluid and air evacuated from the thoracostomy tube, and time in hospital. RESULTS: Median sternotomy was associated with increased total fluid evacuation (median, 12.1 mL/kg; IQR, 15.4 mL/kg; P = .012), whereas rib resection was associated with increased total air evacuation (median, 2.1 mL/kg; IQR, 13.6 mL/kg; P = .06). The presence of preoperative pleural effusion was associated with higher total fluid evacuation (20.6 mL/kg; IQR, 32.1 mL/kg; P = .009), longer duration with a thoracostomy tube in place (42.5 hours; IQR, 41.9 hours; P = .027), and longer hospitalization period (61 hours; IQR, 52.8 hours; P = .025). Cats had a thoracostomy tube in place for a longer time compared to dogs (median, 42.6 hours; IQR, 23.5 hours; P = .043). CLINICAL RELEVANCE: Animals undergoing median sternotomy and rib resection may be expected to have higher fluid and air volumes, respectively, evacuated postoperatively. This often leads to an increased duration of thoracostomy tube usage and a longer period of hospitalization.

Outcome in dogs with invasive adrenal gland tumors that did not pursue adrenalectomy.

OBJECTIVE: To report the survival times in dogs diagnosed with adrenal tumors with vascular or soft tissue invasion that did not undergo adrenalectomy. ANIMALS: Retrospective case series of 32 client-owned dogs. METHODS: The medical records of a referral veterinary hospital were reviewed to identify dogs that were diagnosed with an invasive adrenal mass and did not undergo adrenalectomy between January 2013 and December 2022. Data collected included signalment, examination findings, and diagnostic results from the initial presentation. Descriptive statistics were calculated to summarize dog signalment information, and Kaplan-Meier survival analysis was performed for calculation of median survival time. RESULTS: Most dogs (n = 28) had vascular invasion, primarily into the caudal vena cava. Surgery was offered but not pursued due to perceived risk of sudden death (n = 5), risk of hemorrhage (4), or concurrent diagnosis of disseminated intravascular coagulation (1). Only 1 dog pursued stereotactic body radiation therapy, and 1 was prescribed toceranib phosphate (Palladia). Of these 32 dogs, 30 (93.8%) died or were euthanized and 2 (6.2%) dogs survived. The median follow-up time was 49 days (range, 0 to 1,910 days). The median survival time was 50 days (95% CI, 4 to 194 days). The most common cause of death or euthanasia was hemoabdomen (n = 8). CLINICAL RELEVANCE: Nonsurgical management of invasive adrenal tumors was associated with short survival times in this case series.

Unilateral nephrectomy in dogs is associated with a high rate of intraoperative and postoperative complications.

OBJECTIVE: To determine the incidence of complications in the intraoperative and postoperative period for dogs undergoing nephrectomy for renal disease. ANIMALS: 69 dogs. METHODS: Medical records of dogs undergoing nephrectomies for renal disease were reviewed for signalment, date of surgery, results of blood analyses, and intra- and postoperative complications. Long-term follow-up was obtained via client telephone interview or referring veterinarian medical records. A Fisher exact test was used to assess the relationship between postoperative acute kidney injury and NSAID administration with long-term development of chronic kidney disease. RESULTS: Complications occurred in 44.9% and 42.6% of dogs in the intraoperative and postoperative periods, respectively. Most of these were lower-grade complications, though a total of 7 dogs died during the postoperative period. An acute kidney injury was diagnosed in 12 dogs postoperatively, with 2 dogs euthanized due to the severity of the injury. Long-term follow-up was available for 53 dogs, with 24 (45.3%) dogs developing chronic kidney disease. Postoperative acute kidney injury (P = .385) and NSAID administration (P = .519) were not statistically associated with the development of chronic kidney disease in this population. CLINICAL RELEVANCE: Unilateral nephrectomy is associated with high intraoperative and postoperative complication rates in dogs. Chronic kidney disease was diagnosed in almost 50% of the population with available long-term follow-up.

Treatment of retroperitoneal sarcoma results in improved outcomes.

OBJECTIVE: To report the clinical characteristics, treatments, and outcomes in a cohort of dogs with histologically confirmed retroperitoneal sarcoma (RPS) and to identify potential variables of prognostic significance. ANIMALS: 46 client-owned dogs from 10 clinics with histopathologic diagnosis of a sarcoma originating from the retroperitoneal space. METHODS: Medical records were retrospectively reviewed to obtain information regarding clinical characteristics, treatments, and outcomes. Recorded variables were analyzed to report descriptive data for all cases and overall survival time. Multivariate analysis was utilized to evaluate prognostic factors for overall survival. RESULTS: Hemangiosarcoma was the most common histologic subtype diagnosed (76.1%). Cytoreductive and curative intent surgical excision of the RPS was attempted in 12 and 22 dogs, respectively; 12 dogs underwent no surgery or had an exploratory laparotomy with incisional biopsy only. Nineteen dogs received adjuvant chemotherapy, either injectable or metronomic, and 1 dog received adjuvant radiation therapy. Fourteen of the 34 (41.2%) surgically treated dogs developed evidence of local recurrence, but there was no difference in local recurrence when comparing dogs categorized as curative intent versus cytoreductive surgery. The median overall survival time was 238 days. On multivariable analysis, treatment approach was associated with survival with surgical excision (vs palliative treatment) and adjuvant chemotherapy following surgery being protective against death. A diagnosis of hemangiosarcoma was associated with a greater hazard of death. CLINICAL RELEVANCE: This study demonstrates a substantially greater survival time than previously published and suggests a survival benefit from surgical excision and adjuvant chemotherapy.

Characteristics and outcomes for 61 cats that underwent either surgery or stereotactic radiotherapy as treatment for intracranial meningioma (2005-2017).

OBJECTIVE: To report clinical features and outcomes of cats undergoing either stereotactic radiotherapy (SRT) or surgical excision for the treatment of intracranial meningioma. ANIMALS: 61 client-owned cats. METHODS: Medical records were retrospectively reviewed of cats with intracranial meningiomas that were treated with surgical removal and/or SRT between 2005 and 2017. Signalment, clinical signs, duration of clinical signs, diagnostic imaging reports, histopathology reports, treatment protocol, complications, recurrence or progression, and survival time were obtained from the medical record and through follow-up phone calls. RESULTS: Of the 61 patients, 46 had surgery, 14 had SRT, and 1 had surgery followed by SRT for initial treatment. Significantly more cats that underwent surgery had peritreatment complications compared to the SRT group (P < .0001). Cats that received surgery initially had a significantly longer median survival time (MST) of 1,345 days compared to the MST of 339 days for the SRT cats (P = .002). Fourteen (30%) cats in the surgery group and 4 cats in the SRT group (28%) had MRI- or CT-confirmed tumor regrowth or new tumor growth (P = 1.00). Five cases that had SRT for subsequent recurrence had an MST of 700 days (range, 335 to 1,460 days) after the last treatment. CLINICAL RELEVANCE: SRT proved to be a safe, alternative treatment option for feline patients with intracranial meningiomas; however, the survival times with surgery alone were significantly longer. SRT for the treatment of recurrence following initial surgery may show promising results.

Evaluation of the clinical outcome of hypercalcemia of malignancy and concurrent azotemia in dogs with lymphoma.

BACKGROUND: Hypercalcemia of malignancy (HM) secondary to lymphoma in dogs has the potential to cause renal injury. HYPOTHESIS/OBJECTIVES: Characterize outcomes related to acute kidney injury (AKI) secondary to HM. We hypothesized that dogs do suffer AKI regardless of HM severity at the time of lymphoma diagnosis or relapse. ANIMALS: Retrospective study. Twenty-nine dogs with lymphoma, HM, and azotemia (International Renal Interest Society [IRIS] grade II or higher AKI) that underwent chemotherapy were identified at 2 veterinary institutions. METHODS: Logistic regression and descriptive statistical analysis were performed to evaluate data for potential prognostic factors. RESULTS: After initiating treatment, resolution of hypercalcemia and azotemia occurred in 100% (29/29) and 79.3% (23/29) of dogs, respectively. Resolution of azotemia was influenced by serum creatinine concentration (odds ratio [OR], 0.148; Confidence interval [CI], 0.03-0.734; P = .02) and total hypercalcemia (OR, 0.36; CI, 0.14-0.93; P = .04) at diagnosis, whereas blood urea nitrogen concentration, IRIS grade, sex, and whether or not dogs were hospitalized were not significant factors. At data analysis, 13.8% (4/29) of dogs were alive or lost to follow-up. Of those dead, 4 dogs (15%) had renal disease at the time of death, 2/4 having concurrent lymphoma progression. CONCLUSIONS AND CLINICAL IMPORTANCE: Although AKI may be of clinical concern in dogs with HM secondary to lymphoma at diagnosis, death secondary to renal impairment appears to be infrequent.

Primary extraskeletal osteosarcoma of the post-hepatic caudal vena cava in a dog-Case report.

Extraskeletal osteosarcoma (EOSA) in dogs is a rare malignant mesenchymal tumor of somatic soft tissues or more commonly visceral organs with a poor prognosis. In dogs, EOSAs have been described as arising from multiple locations, but differently from humans, never from a main vessel. In this report, we describe the first case of an EOSA arising from the post-hepatic caudal vena cava in a 7-year-old male neutered mix breed dog. This report focuses on the description of the diagnostic challenges to obtain a preoperative diagnosis, highlights the importance of histopathology for a correct diagnosis, and introduces a new differential diagnosis for an animal presenting with a suspected thrombus of the vena cava.

Indicators of surgical stress and influence of clinical experience, simulation models, and cadaveric laboratory on the stress response of third-year veterinary students performing first elective surgery.

OBJECTIVE: To evaluate the role of simulation models and previous surgical experience on subjective and objective stress levels of students performing their 1st elective surgery within the veterinary curriculum. SAMPLE: 141 third-year veterinary students. METHODS: Using a pre-post experimental design, salivary alpha-amylase, and cortisol were evaluated as markers of physiologic stress response before students' first elective surgery. Student self-reported State-Trait Anxiety Inventory (STAI) scores and quantitative measures of experience were correlated to biomarker results. RESULTS: No association was found for change in salivary biomarkers of stress, alpha-amylase, and cortisol, between baseline and presurgical samples accounting for gender, age, type of elective surgery performed, previous surgical experience, or simulation model use. Salivary cortisol levels were markedly elevated falling between the 66th and 99th percentile compared to an age and gender-matched population. Salivary alpha-amylase levels were also 2 to 3 times higher than those recorded by other health professionals. Veterinary student STAI scores were high falling between the 65th and 73rd percentile compared to working adults in the general population. CLINICAL RELEVANCE: Veterinary students' salivary cortisol, alpha-amylase, and STAI scores fell into the upper 2/3rds of the general population, demonstrating a high level of stress. Simulation models and previous surgical experience were not associated with decreased stress. Further evaluation of the implementation of high-fidelity simulation models and the role of stress on performance is indicated.

Surgical and oncologic outcomes in dogs with malignant peripheral nerve sheath tumours arising from the brachial or lumbosacral plexus.

Malignant peripheral nerve sheath tumours (MPNST) of a plexus nerve or nerve root cause significant morbidity and present a treatment challenge. The surgical approach can be complex and information is lacking on outcomes. The objective of this study was to describe surgical complication rates and oncologic outcomes for canine MPNST of the brachial or lumbosacral plexus. Dogs treated for a naïve MPNST with amputation/hemipelvectomy with or without a laminectomy were retrospectively analysed. Oncologic outcomes were disease free interval (DFI), overall survival (OS), and 1- and 2-year survival rates. Thirty dogs were included. The surgery performed was amputation alone in 17 cases (57%), and amputation/hemipelvectomy with laminectomy in 13 cases (43%). Four dogs (13%) had an intraoperative complication, while 11 dogs (37%) had postoperative complications. Histologic margins were reported as R0 in 12 dogs (40%), R1 in 12 dogs (40%), and R2 in five dogs (17%). No association was found between histologic grade and margin nor extent of surgical approach and margin. Thirteen dogs (46%) had recurrence. The median DFI was 511 days (95% CI: 140-882 days). The median disease specific OST was 570 days (95% CI: 467-673 days) with 1- and 2-year survival rates of 82% and 22% respectively. No variables were significantly associated with recurrence, DFI, or disease specific OST. These data show surgical treatment of plexus MPNST was associated with a high intra- and postoperative complication rate but relatively good disease outcomes. This information can guide clinicians in surgical risk management and owner communication regarding realistic outcomes and complications.

Fluorescence-guided surgical system using holographic display: from phantom studies to canine patients.

Significance: Holographic display technology is a promising area of research that can lead to significant advancements in cancer surgery. We present the benefits of combining bioinspired multispectral imaging technology with holographic goggles for fluorescence-guided cancer surgery. Through a series of experiments with 43D-printed phantoms, small animal models of cancer, and surgeries on canine patients with head and neck cancer, we showcase the advantages of this holistic approach. Aim: The aim of our study is to demonstrate the feasibility and potential benefits of utilizing holographic display for fluorescence-guided surgery through a series of experiments involving 3D-printed phantoms and canine patients with head and neck cancer. Approach: We explore the integration of a bioinspired camera with a mixed reality headset to project fluorescent images as holograms onto a see-through display, and we demonstrate the potential benefits of this technology through benchtop and in vivo animal studies. Results: Our complete imaging and holographic display system showcased improved delineation of fluorescent targets in phantoms compared with the 2D monitor display approach and easy integration into the veterinarian surgical workflow. Conclusions: Based on our findings, it is evident that our comprehensive approach, which combines a bioinspired multispectral imaging sensor with holographic goggles, holds promise in enhancing the presentation of fluorescent information to surgeons during intraoperative scenarios while minimizing disruptions.

Adrenal tumors treated by adrenalectomy following spontaneous rupture carry an overall favorable prognosis: retrospective evaluation of outcomes in 59 dogs and 3 cats (2000-2021).

OBJECTIVE: To conduct a retrospective multi-institutional study reporting short- and long-term outcomes of adrenalectomy in patients presenting with acute hemorrhage secondary to spontaneous adrenal rupture. ANIMALS: 59 dogs and 3 cats. METHODS: Medical records of dogs and cats undergoing adrenalectomy between 2000 and 2021 for ruptured adrenal masses were reviewed. Data collected included clinical presentation, preoperative diagnostics, surgical report, anesthesia and hospitalization findings, histopathology, adjuvant treatments, and long-term outcome (recurrence, metastasis, and survival). RESULTS: Median time from hospital admission to surgery was 3 days, with 34% of surgeries being performed emergently (within 1 day of presentation). Need for intraoperative blood transfusion was significantly associated with emergent surgery and presence of active intraoperative hemorrhage. The short-term (≤ 14 days) complication and mortality rates were 42% and 21%, respectively. Negative prognostic factors for short-term survival included emergent surgery, intraoperative hypotension, and performing additional surgical procedures. Diagnoses included adrenocortical neoplasia (malignant [41%], benign [12%], and undetermined [5%]), pheochromocytoma (38%), a single case of adrenal fibrosis and hemorrhage (2%), and a single case of hemangiosarcoma (2%). Local recurrence and metastasis of adrenocortical carcinoma were confirmed in 1 and 3 cases, respectively. Overall median survival time was 574 days and 900 days when short-term mortality was censored. No significant relationship was found between histopathological diagnosis and survival. CLINICAL RELEVANCE: Adrenalectomy for ruptured adrenal gland masses was associated with similar short- and long-term outcomes as compared with previously reported nonruptured cases. If hemodynamic stability can be achieved, delaying surgery and limiting additional procedures appear indicated to optimize short-term survival.

Metastatic carcinoma of unknown origin in a dog.

Although cancer of unknown primary origin (CUP) is well-described in the human literature, it is not as well-understood within veterinary medicine. This case report represents one of few focused on describing CUP in a dog. Key clinical message: Metastatic CUP should be considered as a differential diagnosis despite being a rare disease entity that is infrequently reported within the veterinary literature.

Carcinome métastatique d'origine inconnue chez un chien. Bien que le cancer d'origine primaire inconnue (CUP) soit bien décrit dans la littérature humaine, il n'est pas aussi bien compris en médecine vétérinaire. Ce rapport de cas représente l'un des rares à s'intéresser à la description du CUP chez un chien.Message clinique clé:Le CUP métastatique doit être considéré comme un diagnostic différentiel bien qu'il s'agisse d'une entité de maladie rare rarement rapportée dans la littérature vétérinaire.(Traduit par Dr Serge Messier).

Long-term outcomes associated with a modified versus traditional closed anal sacculectomy for treatment of canine anal sac neoplasia.

OBJECTIVE: To report the short-term and long-term outcomes of dogs that underwent the modified closed and traditional closed anal sacculectomy procedures for the treatment of anal sac neoplasia. ANIMALS: 90 client-owned dogs. Methods: The medical records of 2 tertiary referral hospitals were reviewed to identify dogs that underwent anal sacculectomy for treatment of anal sac neoplasia between January 2016 and December 2020. Data collected included signalment and preoperative diagnostic findings. The occurrence of intraoperative and postoperative complications, short-term outcomes, and long-term outcomes were also collected. Descriptive statistics were calculated to summarize dog signalment information, and recurrence, metastasis, and survival proportions were compared between techniques using Fisher exact tests. RESULTS: 35 and 55 dogs, respectively, underwent the modified or traditional closed anal sacculectomy procedure. Minor postoperative complications that resolved with minimal intervention occurred in 5 of 35 (14.3%) modified approach dogs and 12 of 55 (21.8%) traditional approach dogs. Tumor recurrence was confirmed in 8 of 35 (22.9%) modified and 8 of 55 (26.4%) traditional approach dogs and was suspected in 3 of 35 (8.6%) and 6 of 55 (13.2%; P = .68), respectively. Confirmed metastatic disease was identified in 8 of 35 (22.9%) and 14 of 53 (26.4%) modified and traditional approach dogs, respectively, and was suspected in 4 of 35 (11.4%) and 7 of 53 (13.2%). Sixty-three (70%) dogs survived to study conclusion. CLINICAL RELEVANCE: No benefits in complication rate or local recurrence were identified in dogs following the modified approach as opposed to the traditional closed anal sacculectomy technique.

A novel two-catheter method for urethral catheterization improves success rates of urethral catheterization in female dogs and cats weighing less than ten kilograms.

OBJECTIVE: To compare the success rates for urethral catheterization in clinical patients using the traditional and 2-catheter techniques when placed by personnel of all experience levels. ANIMALS: 38 female cats and dogs weighing less than 10 kg were prospectively enrolled. METHODS: Enrolled animals were randomized to have a urethral catheter placed by the traditional technique or the 2-catheter method under sedation or general anesthesia. Any qualified hospital personnel of any experience level were allowed to place the catheter. If after 5 minutes the animal was not successfully catheterized, the alternate method was performed. The previous experience of the catheter placer, animal signalment, animal condition that necessitated catheter placement, time to successful placement, and which technique was successful was recorded. RESULTS: The 2-catheter technique was more successful than the traditional method (60.5% and 34.2%, respectively) for urethral catheterization when used by a variety of hospital personnel. The 2-catheter technique was successful in 63.3% of dogs and 66.6% of cats, while the traditional method was successful in 36.6% of dogs and 33.3% of cats. Eight of 9 (88.9%) novice catheter placers that placed their first urinary catheter in this study succeeded with the 2-catheter technique and only 1 was successful with the traditional method. CLINICAL RELEVANCE: The 2-catheter technique has a higher rate of success for placement of female urinary catheters in small patients that are unable to have concurrent digital palpation. This technique may also be helpful in the inexperienced catheter placer population to aid in guidance into the urethral papilla.

Risk factors influencing death prior to discharge in 302 dogs undergoing unilateral adrenalectomy for treatment of primary adrenal gland tumours.

Adrenalectomies for canine adrenal tumours are associated with peri-operative morbidity and mortality. Objectives of this study included assessing the prognostic value of tumour- or surgery-related variables in predicting peri-operative mortality and overall survival in dogs undergoing adrenalectomies for primary adrenal tumours as well as pre-treatment with phenoxybenzamine on survival to discharge with pheochromocytomas specifically. A multi-institutional retrospective cohort study was performed across nine institutions. Electronic medical record searches identified 302 dogs which met the inclusion criteria. Data collected included dog-related, tumour-related, treatment-related, surgery-related, and outcome variables. Univariate and multivariable logistic regression and cox proportional hazards models were used to identify variables associated with death prior to discharge and tumour-related survival. Overall, 87% of dogs survived to discharge with a tumour-related survival time of 3.96 years. Post-operative complications were reported in 25%. Increased surgical time (p = 0.002) and pre-surgical medical treatment other than phenoxybenzamine (p = 0.024) were significantly associated with increased peri-operative mortality while ureteronephrectomy (p = 0.021), post-operative pancreatitis (p = 0.025), and post-operative aspiration pneumonia (p < 0.001) were significantly associated with decreased overall survival. Phenoxybenzamine pretreatment had no effect on peri-operative mortality. Thirty-seven of 45 (82%) dogs with pheochromocytomas not pretreated survived to discharge, and 50 of 59 (85%) dogs with pheochromocytomas pretreated with phenoxybenzamine survived to discharge (p = 0.730). This study provides information on risk factors for death prior to discharge and tumour-related survival that may help guide clinical management and owner expectations. In addition, the study findings challenge the previously reported benefit of phenoxybenzamine for pretreatment of dogs undergoing adrenalectomies for pheochromocytomas.