Anaesthetic Management of a Labrador Retriever Undergoing Adrenalectomy for Phaeochromocytoma Excision, a Case Report

Abstract

Perioperative management of cases undergoing phaeochromocytoma removal should aim at normalising blood pressure and heart rate, restoring volume depletion, and preventing catecholamine release induced by surgical manipulation. In this case report, a novel pharmacological approach in a dog undergoing surgical tumour excision is described. A 7-year-old 25-kg spayed female Labrador Retriever presented for repeated episodes of generalised weakness, pale mucous membranes, tachycardia, tremor, panting, vomiting, and hypertension over the last month was referred for surgical treatment of a left-sided adrenal tumour with invasion of the caudal vena cava. Severe hypertensive episodes occurred repeatedly, starting early during the anaesthetic period, while clipping and cleaning the abdominal area, and continued intraoperatively when the tumour was handled. Moderate hypotension occurred once the tumour was isolated and worsened during temporary caudal vena cava flow interruption and cavotomy. The patient was treated preoperatively with phenoxybenzamine to prevent hypertensive crises. Intraoperatively, magnesium sulphate and urapidil were used to control blood pressure. This treatment was effective in reducing the magnitude of blood pressure spikes but not sufficient to prevent hypertensive peaks, especially during tumour manipulation. Hypotension was treated with synthetic colloid and crystalloid boli, and noradrenaline continuous infusion. Blood transfusion was performed in response to acute bleeding during cavotomy. The dog recovered successfully from anaesthesia and its quality of life was deemed excellent by the owner at the last follow up, 22 months after surgery. The histopathology confirmed the diagnosis of phaeochromocytoma with an invasion of the phrenicoabdominal vein. In the present case, we obtained a successful outcome but failed to provide haemodynamic stability throughout the procedure.

Anaesthetic management of a dog undergoing unilateral adrenalectomy for phaeochromocytoma excision using a partial intravenous anaesthetic protocol

“…In the present case, the multimodal analgesia consisted of premedication with methadone, CRIs of dexmedetomidine and maropitant, and a TAP block. The TAP block was used to desensitize the abdominal wall ( Skouropoulou et al ., 2018 ; Santos et al ., 2018 ) and has been reported in several adrenalectomies ( Merlin and Veres-Nyéki, 2019 ; Maidanskaia et al ., 2022 ). However, it does not provide visceral analgesia of the abdomen, conversely to other techniques, such as lumbosacral epidural ( Maidanskaia et al ., 2022 ; Merlin and Veres-Nyéki, 2019 ), thoracic epidural ( Viilmann and Vettorato, 2021 ), thoracic paravertebral block ( Merlin and Veres-Nyéki, 2019 ; López-Ramis et al ., 2022 ;), and Quadratus Lumborum Block, which has proven to be efficacious in canine ovariohysterectomies ( Viscasillas et al ., 2021 ) and in a human patient for phaeochromocytoma resection under laparoscopy ( Giordano et al ., 2019 ).…”

“…The anesthetic management of patients undergoing phaeochromocytoma resection is challenging. Apart from a few case reports ( Ferreira and Raszplewicz, 2016 ; Miller and Pawson, 2019 ; Viilmann and Vettorato, 2021 ; Maidanskaia et al ., 2022 ; ) and a single study ( Merlin and Veres Nyéki, 2019 ), there is a gap in the veterinary literature investigating the efficacy of different intraoperative anesthetic protocols on patient stabilization and outcome.…”

“…To control intraoperative blood pressure spikes, various pharmacological agents are commonly used in human patients: sodium nitroprusside, phentolamine, prazosin, nitroglycerin, magnesium sulfate, nicardipine, diltiazem, esmolol ( Ahmed, 2007 ), urapidil ( Tauzin-Fin et al ., 2020 ), increase in inhaled agents ( Khetarpal et al ., 2014 ) or remifentanil ( Jung et al ., 2012 ). In canine patients, in the few cases reported, hypertension peaks were treated with phentolamine ( Kyles et al ., 2003 ; Merlin and Veres-Nyéki, 2019 ), nitroprusside ( Kyles et al ., 2003 ; Miller and Pawson, 2019 ), acepromazine ( Ferreira and Raszplewicz, 2016 ), increase in inhaled agents ( Ferreira and Raszplewicz, 2016 ; Miller and Pawson, 2019 ), fentanyl ( Ferreira and Raszplewicz, 2016 ), magnesium sulfate ( Viilmann and Vettorato, 2021 ; Maidanskaia et al ., 2022 ) or urapidil ( Maidanskaia et al ., 2022 ). Importantly, the availability and accessibility of these drugs are often limited in veterinary medicine, and dexmedetomidine may help reduce the need for anti-hypertensive treatments intraoperatively.…”