Anal Furunculosis in Dogs

Anal Furunculosis is an intensely painful condition in dogs that results in ulceration around the anus. In this factsheet, you’ll find everything you need to know about this condition, including which breeds are predisposed to the condition, causes, clinical signs, diagnosis, and treatment options. But first, what exactly is Anal Furunculosis in dogs?

Which Breeds are at Risk of Canine Anal Furunculosis?

Canine Anal Furunculosis is most commonly seen in middle-aged to elderly German Shepherd (and crosses), Irish Setters, Black Labradors, and other large breeds.  This accounts for around 82% of all cases, but other breeds can be affected.

What Causes Anal Furunculosis in Dogs?

There have been a number of theories over the years surrounding the cause of dog Anal Furunculosis. However, many of these has since been refuted, such as having a wide-based tail and increased numbers of sweat glands in the anal canal,  broad-based conformation of the perianal area, or anal sac rupture. In fact, many now consider the disease to be caused by immunological factors, and have noted similarities between Anal Furunculosis and Chron’s Disease in humans. 

Analysis suggests that lesions develop due to a lack of immune system defences that would usually protect the intestines and perianal skin from bacteria. Meanwhile, a separate part of the immune system becomes overactive due to the presence of higher-than-usual levels of bacteria. This results in inflammation and ulceration.

Signs of Anal Furunculosis in Dogs

Anal Furunculosis is a particularly painful condition for dogs, therefore pain when defecating is a common sign. Other clinical signs of Anal Furunculosis in dogs include:

How Do We Diagnose Dog Anal Furunculosis?

Anal Furunculosis is diagnosed via a thorough clinical assessment, where dogs are typically sedated as the assessment may be uncomfortable. During the assessment, hair around the anus will be clipped, the area will be thoroughly cleaned, and clinical signs will be documented before a diagnosis is made based on a visual inspection.

Canine Anal Furunculosis Treatment

The main treatment for canine Anal Furunculosis is drug therapy using ciclosporin or other immunosuppressive drugs like azathioprine and prednisolone. This aims to shrink lesions, and may clear them up completely in some cases.

During treatment, regular check-ups will be required to monitor progress and the efficacy of medications, as well as blood tests in some cases to monitor liver and kidney function.

Where drug therapy is not satisfactorily effective, surgery may be considered to remove any remaining lesions. This involves removal of the active lesions and some of the scar tissue as well as the anal glands from one or both sides.