Hypocalcemia Following Surgical Treatment of Metastatic Anal Sac Adenocarcinoma in a Dog

Canine Apocrine Gland Anal Sac Adenocarcinoma: A Review

Apocrine gland anal sac adenocarcinoma (AGASAC) is a relatively uncommon tumor in the dog and comprises approximately 17% of perianal malignancies; however, it is one of the most common causes of paraneoplastic hypercalcemia. Clinical signs in affected dogs most commonly are associated with mechanical obstruction caused by the primary tumor or enlarged regional metastatic lymph nodes and the effects of paraneoplastic hypercalcemia when present. Surgical excision of the primary tumor and metastasectomy of affected locoregional lymph nodes is the preferred initial treatment option for most dogs, although radiation therapy and adjuvant chemotherapy are commonly incorporated into multi-modality treatment plans. A significant role for the use of adjuvant chemotherapy has not been clearly demonstrated. Prolonged survival times are possible, especially for dogs with smaller primary tumors and for dogs that undergo further treatments for recurrent disease. In this article, we review the clinical signs, diagnosis, staging, treatment, and prognosis of AGASAC in the dog.

Surgical management of primary, metastatic and recurrent anal sac adenocarcinoma in the dog: 52 cases

OBJECTIVES

To report the outcomes and complications of a cohort of dogs with primary and recurrent anal sac adenocarcinoma managed with surgery as the first-line treatment. To report the use of lymph node cytology for identification of metastatic disease.

METHODS

Retrospective review of case records of a single referral centre population of dogs diagnosed with anal sac adenocarcinoma.

RESULTS

Fifty-two clinical cases were identified. Altered ultrasonographic appearance of lymph nodes was highly consistent with metastatic disease as assessed by cytology and histopathology. Seven of 58 (12%) perineal surgeries had reported minor complications and seven (12%) others required further surgical intervention. Minor controllable intraoperative bleeding was the only complication noted associated with lymph node extirpation in two of 39 (5%) metastectomy procedures. Six dogs (12%) suffered local recurrence and 22 (42%) developed subsequent or recurrent nodal metastatic disease. From the time of detection of disease recurrence, median additional survival associated with a second surgical intervention was 283 days.

CLINICAL SIGNIFICANCE

Coeliotomy for lymph node metastatectomy in dogs with adenocarcinoma of the anal sac has low morbidity and should be considered in patients presenting with evidence of regional metastatic disease both at initial presentation and with recurrent disease.