Dog - Anal Furunculosis

What is anal furunculosis?

Anal furunculosis is also called perianal fistula or perianal sinus. It is a condition affecting the German Shepherd dog more than any other breed in the UK. However Sheepdogs, Irish Setters and crossbreeds, particularly those of German Shepherd breeding, can also be affected.

How do I recognise it? What are its signs?

The condition can often go undetected in its early stages and is frequently discovered by a veterinary surgeon during a routine health check, e.g. booster vaccinations etc. Initially the dog may show no signs. However, as the disease progresses straining, with painful defaecation, often with blood streaked faeces may be noticed. There will be excessive licking and sometimes self-mutilation together with a reluctance to sit. Tail movements may become painful and there may be resentment of any approach to the back end. Many dogs show vague personality changes. If your dog does show any of these signs a veterinary check-up is a good idea.

What does the condition involve?

The condition involves multiple chronic fistulous tracks (tunnels) or ulcerating sinuses involving the whole of the anal region and surrounding skin. The condition could be compared with a carbuncle - a many headed abscess.

What is the cause?

The cause is not fully understood although impaction (clogging) or infection of the anal sacs (anal glands), and the adjacent sinuses and crypts around the anus certainly contributes. Poor ventilation of the anal region at one time was considered a major contributory factor and tail amputation was actually advocated as a method of treatment.

Work over the last decade indicates an auto-immune basis (where the body's imune system attacks normal cells). Some families of German Shepherd dogs appear particularly prone so there may be a genetic basis.

Is there any sex or age predisposition?

No. Dogs of both sexes can be affected. Dogs over about one year can become victims of the disease. There appears to be no predilection for sex although it has been suggested that unneutered animals, of either sex, may have a higher prevalence.

Treatment

Since even today the cause of the condition is not fully understood it is not surprising that various forms of treatment are currently used.

Medical treatment involving antibiotics for the infection and analgesics for the pain and discomfort will often result in improvement particularly in mild cases diagnosed early but unfortunately recurrence can occur.

Work over the last ten to fifteen years which has definitely established the immune mediated nature of this disease has led to the use of cicolosporin, a powerful immunosuppressant drug widely used in human medicine. This drug does offer a better chance of control if not total cure, than any other drug presently available but is extremely expensive. However its cost can be reduced somewhat if combined with other drugs such as ketaconozole which although also expensive, is not as expensive as ciclosporin and does allow reduction of dosage by sometimes 50% or more.

Other palliative (relieving but not curing) measures include simple procedures such as increasing ventilation by clipping the area, particularly in full coated dogs, together with careful systematic bathing using antiseptics which we will provide just to keep the area clean, especially after defaecation.

Surgery to remove as much infected tissue as possible together with removal of the anal sacs often followed by cryotherapy certainly relieves pain and discomfort in many cases and often results in a dramatic improvement. Cryosurgery, which involves the application of intense cold to the affected area appears to reduce further infection and also appears to stimulate healing.

Is treatment curative?

Using a combination of surgery, drug therapy (ciclosporin etc) and other modalities such as cryotherapy, laser treatment etc, 80% of affected dogs will, after treatment, go on to enjoy normal happy lives without substantial inconvenience. Success however very much depends on early diagnosis and treatment.

Until very recently approximately 20% of cases did not respond to treatment irrespective of the type. With the use of ciclosporin these numbers have fallen dramatically although unfortunately the use of this drug cannot in all cases be considered a cure. However, it is one of the best palliative agents presently available.