Anal sac cancer causes local problems, mainly because of pain and straining to defecate. Anal sac apocrine gland adenocarcinoma also leads to systemic issues, including hypercalcemia and metastasis. Affected patients are older female dogs in 90 percent of the cases. A few cases have been described in cats.
It is important to keep an open mind. Differential diagnosis for perianal disease includes anal sac impaction, abscess (which may rupture), sacculitis, perianal adenomas, perineal hernias, perineal fistulas and other malignancies, such as perianal malignant melanoma. Any of these conditions affect the quality of life of the patient.
 |
| A preoperative view of a left anal sac adenocarcinoma in a 9-year-old male Akita mix. Photo courtesy of Dr. Phil Zeltzman. |
An anal sac tumor is suspected on rectal exam. If it is large enough, subcutaneous swelling may be visible. Occasionally, the tumor is bilateral. A diagnosis can sometimes be reached with cytology if enough cells exfoliate. Histopathology gives a definitive diagnosis. Incisional biopsies are rarely used, whereas excisional biopsy is typically the preferred course of action.
Standard preoperative workup includes a CBC and blood chemistry, including a calcium level. Approximately 25 percent of patients are affected by paraneoplastic hypercalcemia (See our bonus content on differential diagnosis of hypercalcemia). Abdominal radiographs or ultrasound are helpful to diagnose metastasis to the sublum...
Copyright 2009 BowTie Inc.
Click here to read the rest of this article from Veterinary Practice News
