Anal furunculosis or perianal fistula as it is called
in North America is a subject about which many German Shepherd Dog
owners have very real concerns. This is the impression that I gained
when I have talked with many GSD owners out of the veterinary
environment at shows, trials etc. Although by far the greatest
preponderance of cases occur in GSDs and GSD crosses, I have seen
occasional cases in Collies, Sheepdogs and Labrador Retrievers.
During the years of my particular involvement with the condition and
its treatment I also received a fair number of the larger terriers
and Schnauzers with `look-alike’ signs of anal furunculosis with
obvious perianal sinuses. These, on investigation, invariably
turned out to be proctitis and perianal pyoderma rather than true
anal furunculosis. Recent studies have shown that the Leonberger
also suffers from the syndrome.
I became interested in the condition nearly 30 years
ago when I developed an interest in cryosurgery and certainly for
the ensuing 20 years felt that a cryosurgical approach to the
problem, in my hands, resulted in the best chance of success.
Some patients responded dramatically and after one session of
cryotherapy under a general anaesthetic, needed no further
treatment. These however were the exception, the majority needed
repeat treatments and in some, alas, we never got on top of the
Over the years, after treating many hundreds of cases
I began to doubt whether the `rotting anus’ was indeed the main
problem for these poor dogs. It seemed to me that an increasing
proportion suffered other chronic conditions including chronic
dermatitis and probably most commonly, bowel upsets. These varied
from mild gastritis, `bilious attacks` to chronic diarrhoea. These
dogs were often found to have inflammatory bowel disease, (IBD), due
to food allergies or some immune mediated problem.
Pannus, a particularly GSD prone condition of the
eventually to pigmentation of the cornea, was also often noted.
Gradually it was being recognised by the profession
that pannus and IBD were primarily immune mediated conditions. I
began to think along the same lines in respect of anal
furunculosis. This was long before a formal research project was
set up at Bristol Vet School. Perhaps it was a bit “putting the
cart before the horse” but I tried to address the common bowel
conditions in these dogs presented with sore backsides, solely from
the simplistic view that any surgery I performed at the rear end
would have a better chance of success if the dog was not
continuously washing it in uncontrolled faecal voiding.
Year on year the rear end of the GSD has provided
endless topics for discussions at BSAVA. If it isn’t hip dysplasia,
then it is anal furunculosis with an endless variety of speakers
from home and abroad, me included.
A couple of years ago I was fascinated to listen to
Dr Dick White from the Queens Veterinary School Hospital, Cambridge,
discussing whether the condition was surgical or medical. Despite
being a surgeon he was unequivocal that the condition should now be
treated as a medical rather than a surgical problem. This was
basically due to the fact that recent work had shown that the
condition did appear to be immune mediated. It has many
similarities with human Crohne’s Disease.
Recent work has indicated that the disease really
represents only one aspect of abnormal immune function. This has
resulted in a tremendous change in the management of the condition.
Further investigation also confirmed that anal furunculosis is
frequently accompanied with IBD.
The advent of commercially available hypo-allergenic
diets led to a major break through in the control of diarrhoea and
gas formation in with chronic bowel disease. If these dogs also
suffered anal fistulae, it was noted they showed improvement around
the anal region following treatment that stabilised if not cured the
bowel problem. It was for these reasons that over the last
several years there has been this gradual shift towards medical
rather than surgical treatment for anal furunculosis.
Treatment today is directed towards dietary
management and the control of the immune problem as a whole rather
than simply treating the perianal fistulae. Over the years these
have been subject to a tremendous variety of treatments, the
proponents of which all claim success, me included with my
cryosurgery! Treatments have varied from tail amputation to
cauterisation of the fistulae through meticulous surgery to
cryosurgery and laser therapy.
It is a sure sign that we do not know the cause and
therefore cannot design a logical treatment when such variety of
`cures’ is on offer.
Years ago in the really refractive cases I would use
corticosteroids (cortisone) , solely to reduce the inflammation and
make the dog more comfortable. Today the same drug is frequently
used in high immunosuppressive doses initially. This is then
reduced and continued long term at the reduced dose. This is often
combined with newer immunosuppressive drugs such as Cyclosporine.
In really refractive cases this combined with hypo-allergenic diets
has resulted in spectacular improvements in up to 90% of cases
Cyclosporine is the immunosuppressive drug of choice
and sometimes its effect is little short of miraculous. However
the one drawback is its price. Using cyclosporine on a dog the size
of a GSD will soon exhaust insurance cover!
What was I saying about the ever green nature of the
subject at BSAVA? This year I listened to Bryden Stanley from
Michigan State University, speaking on the subject. She made it
quite clear that local cleansing of the affected area with topical
and systemic antibiotic medications was palliative at best and
historically they always ended up at the surgeon’s door! Her view
was that surgery yielded satisfactory short term results in up to
80% of cases but recurrence rates were high, (50-90%) and
complications not uncommon. Using cryotherapy I would not put
recurrence rates at more than about 30% but they certainly did
occur, the most common of which were faecal incontinence and anal
stricture. However both of these conditions could be controlled in
the majority of cases.
Dr Stanley then discussed the results of using
cyclosporine combined with ketaconozole.
This allows a much lower dose of cyclosporine to be
used thus reducing the cost, although of course the ketaconozole
then has to be paid for. This is much more reasonable than the cost
of cyclosporine so the treatment becomes almost affordable.
Combine the treatment with corticosteroid therapy and
a suitable diet, usually involving an alternative protein source and
a high success is achievable long term.
The question then remains, what about the anal sacs?
(glands) In retrospect one of the reasons for my continued belief
in cryotherapy was perhaps the fact that I always ensured that the
anal glands were surgically removed before cryosurgery was
attempted. This was solely because the majority of anal sacs that I
examined in dogs presented with anal furunculosis were invariably
chronically infected. It was my belief that leaving these in place
resulted in a continual source of re-infection. Perhaps I was naïve
but during her presentation I felt Bryden Stanley emphasised the
need for anal sac removal.
I would be interested to learn from any readers whose
dogs have been treated with cyclosporine.
Trevor Turner –
24th April 2003.