Circumanal glands

The circumanal glands, (perianal glands ; hepatoid glands), are specialized sebaceous glands located around the anus in some domestic animals.

1. Terminology and Location

• Also called hepatoid glands due to their histological resemblance to hepatocytes (liver cells).

• Found in the perianal region, specifically in the skin surrounding the anus, and not associated with the anal sacs (paranal sinuses).

• Located in the dermis and subcutis, especially around:

  • The dorsal and lateral margins of the anus.

  • The prepuce, tail base, thighs, and dorsal back in some cases.

2. Structure and Histology

• These are modified sebaceous glands composed of:

  • Peripheral basal reserve cells (germinal layer).

  • Large polygonal hepatoid cells (eosinophilic cytoplasm, central nuclei).

• Glands are compound tubuloalveolar.

• Ducts open into hair follicles or directly onto the skin surface.

3. Species Differences

a) Dog

• Highly developed.

• Most prominent in intact males, being androgen-sensitive.

• Play a minor role in territorial marking and skin function.

b) Cat

• Poorly developed or absent.

• Not clinically significant.

c) Other domestic animals

• Not clearly defined or absent (e.g., ruminants, horses, pigs).

• No known clinical significance.

4. Clinical Significance

a) Perianal Gland Adenoma

• Most common perianal tumor in dogs.

• Benign, slow-growing.

• Occurs almost exclusively in intact males due to androgen-dependence.

• Rare in neutered males and females.

• Common locations: around the anus, prepuce, tail.

b) Perianal Gland Adenocarcinoma

• Less common but malignant.

• Not hormone-dependent.

• Can metastasize, unlike adenomas.

c) Diagnosis and Treatment

• Diagnosis via histopathology.

• Castration often causes regression of benign adenomas.

• Surgical excision is curative in most cases.

Differences between circumanal glands and glands of paranal sinus (paranal glands)