Small Animal Dermatology, 3rd edition

chapter

Anal^9

Furunculosis/Perianal

Fistula

DEFINITION/OVERVIEW

 Characterized as a chronic, often relapsing, inflammatory disease with multiple fis-

tulous tracts or ulcerating sinuses involving the perianal tissues.

 Tracts may interconnect and may perforate the anus.

 Causes significant malodor, ulceration, suppuration, and pain.

ETIOLOGY/PATHOPHYSIOLOGY

 Etiology unknown; proposed causes include:
Multifactorial immune-mediated process (T cell mediated)
Impaction and infection of the anal sinuses and crypts
Infection of the circumanal glands and hair follicles
Anal sacculitis (may be a sequela)
Deep staphylococcal folliculitis
Low tail carriage and a broad tail base predisposing to inflammation and infec-

tion due to poor ventilation, accumulation of feces, moisture, and secretions

High density of apocrine sweat glands in the cutaneous zone of the anal canal

of German shepherd dogs leading to apocrine gland inflammation (hidradenitis

suppurativa).

 Epithelial-lined sinus tracts develop in the perianal tissue.

 Associated with colitis in German shepherd dogs (50%) similar to Crohn’s disease in

humans (possible enteral triggers).

 Excessive scar tissue formation around the anus results in tenesmus and dyschezia.

 Hidradenitis suppurativa may be associated with immune or endocrine dysfunction,

genetic factors, and poor hygiene.

SIGNALMENT/HISTORY

 Dogs.

 German shepherd dog (84%) and Irish setter most commonly affected breeds.

 Mean age, 5–7 years; range 7 months to 14 years.

Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.

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