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 condition.
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 eye, leading 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 furuncuosis.
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
treated.
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 reinfection. 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.
Of
all the topics I have written about in the column, none has stimulated
more reader response than anal furunculosis; letters, telephone
calls, e-mails and even a couple of comments to me from some people
at shows.
To date all the dogs involved have been GSDs with
an age range of under one year to over 10 years. The exception
is a 10 years old Pembroke Corgi bitch, apparently she developed
the problem early this year. The owner e-mailed me to comment that
her vet, who has been in practice for over thirty years has never seen
this condition “in a bobtail before.” I would tend to agree. I
remember one of the treatments advocated about forty years ago was amputation
of the tail of the GSD because it was considered that with the increasing
angulation seen in the breed, the close lying tail prevented air
circulation around the perineal area and in consequence allowed the infection
to spread.
This particular dog is interesting because the
owner’s case history is absolutely typical even if the breed is
anything but so. I would certainly agree with her veterinary
surgeon. I have never seen a case of anal furunculosis in a Corgi
but if one accepts that the condition is immune mediated in origin
there is really no reason why Corgis should not be affected just like
many other breeds.
The progress of the disease in this dog is interesting
and has obviously been carefully recorded by the owner.
Initially it was noted that the anal region appeared wet and on
investigation the owner found the skin around the anus was red.
This was then followed by the fistulous tracts which appeared first
on one side and then the other. It is often at the red and wet stage
that veterinary surgeons will pick up early signs of the condition, often
when the dog is presented for routine vaccination, etc.
In this particular case the dog was prescribed Cyclosporine without
delay. The owner mentions it cost £93 for thirty capsules.
The original dose was two 50 mg capsules per day. As I mentioned in
the previous article the response was little short of dramatic and
the dose was soon reduced to just one capsule a day. This particular
dog does not appear to be showing other problems such as bowel syndrome
and this may be due in part to the fact that she was fed a normal diet
of tripe and wholemeal biscuit.
Obviously some of the cases that have been reported
to me in GSDs have clearly had a multiplicity of problems including
most commonly IBD (Inflammatory Bowel Disease) Treatment of
the bowel problem as well as the anal furunculosis is imperative
but this of course increases the cost to the owner since the provision
of special diets, be they commercial or home prepared inevitably involves
extra cost, the cost of which in the case of suspected dietary allergy
can be lifelong.
From your response one factor stands out, Cyclosporine
although frighteningly expensive, nonetheless evokes a better
response than any of the other methods of treatment in anal furunculosis
that are currently practised.
These results have been in accordance with the
figures quoted by Dr Bryden Stanley in her presentation at BSAVA
congress in April. She reported results using Cyclosporine
of 100% improvement in clinical signs with an 80-8=90% of resolution
of lesions.
In the studies quoted long term results were also
far more encouraging than those she quoted with other methods
of treatment (60-90%). With Cyclosporine recurrence is quoted
at 30-50%. This also appears to be associated in the main
with anal sac problems. I am surprised under the circumstances that
anal sacs are not removed earlier in the disease. Considering the
cost of Cyclosporine, operation to remove the anal sacs would be very
cost effective it is reduced the need to repeat the courses of Cyclosporine
which seems to be the trend according to my correspondents.
The good news is, of course, this work does appear
to indicate that the dose of Cyclosporine can be reduced by up
to 75% with the introduction of another drug, Ketaconozole, which
prevents the breakdown of Cyclosporine by the liver and thus a much
lower dose can be used.
Ketaconozole is itself an expensive drug but only
approximately one third the cost of Cyclosporine. Thus
overall a combination of the two drugs can become almost affordable.
Therefore the outlook is a lot better than it
ever has been for dogs with anal furunculosis but although the
initial short term results of Cyclosporine appear little short
of miraculous be forewarned that relapses can and do occur, necessitating
further courses of the drug. Furthermore it does appear that
even with the initial dramatic improvement the Cyclosporine should
nevertheless be continued for three to four months otherwise relapses
are likely to occur. However if these do occur the lesions can be treated
far more effectively by surgical means and if the anal sacs are removed
as soon as possible you have then done everything possible to ensure this
awful condition is kept in check.
One final word, as a result of all the research
I have undertaken into this condition particularly recently,
I am more than convinced than ever that if I decide to enquire a
German Shepherd Dog I would endeavour to secure the highest level
of pet health insurance that I could afford!
