Anal Furunculosis

What is Anal Furunculosis?

It is a condition that is often known as Perianal Fistula Disease, and is characterized by ulceration of the perianal area (i.e. tissue around the anus) and the formation of 'waters' (i.e. sinuses) in this area.

Affected dogs show signs of straining, excessive licking of the area, blood in their bowel motions, and abnormal carriage of the tail. It is largely seen in German Shepherd dogs, but has also been seen in Collies, Irish Setters, Labradors and Old English Sheepdogs to name some breeds.

What are the Possible Causes of Anal Furunculosis?

The actual cause is unknown though it appears there may be an underlying immune system dysfunction in affected dogs. Other possible contributing factors include infectious agents, hormonal influences and the anatomy of the affected area in some breeds.

How are Affected Dogs Treated?

Until recently anal furunculosis affected dogs have responded poorly to medical treatment.

Many surgical approaches have been attempted, including removal of tissue surrounding the anal area, cryosurgery where the affected tissue is frozen using liquid nitrogen, amputation of the tail to expose the affected area, removal of the affected tissue, and removal of both anal glands. These procedures quite often come with post operative issues such as wound breakdown, stricture formation and fecal incontinence. Better results have been achieved with surgical removal of the affected tissue and both anal glands followed by use of post operative Flagyl as an antibiotic medication.

Attempts to medically treat affected dogs have involved using immunosuppressants such as cortisone, azothioprine, cyclosporine and antibiotics such as Flagyl or ointments such as Tacrolemis with moderate success.

Recently cyclosporine has been used alone twice daily to treat anal furunculosis for a period of up to 20 weeks with positive results. Any residual lesions are then treated surgically.

Such management regime has given a remission of the condition for periods of 14 months or more. However, the cost incurred is quite prohibitive.

A more recent treatment method is combining cyclosporine with ketaconazole. As ketaconazole inhibits the ability of liver to breakdown cyclosporine needed to successfully treat anal furunculosis, the dose of cyclosporine required for treatment, therefore, is reduced. Such combination of medications is no more successful than using cyclosporine alone, but is significantly less costly. Remission times are similar, but again recurrence occurs in at least 30% of patients.

As an alternative, treatment with immunosuppressive ointments such as Tacrolemis for up to 16 weeks (i.e. use for 4 weeks beyond clinical improvement) has resulted in either complete resolution or significant improvement, especially when used on milder lesions.

Regardless of the treatment approach used, dogs should also be fed fecal softners or soft food so using their bowel becomes easier and less painful. Their affected areas should also be cleaned regularly.