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“You think it’s his
what?” asked the incredulous owner of the uncomfortable Basset Hound
on the exam table. I restated my diagnosis, knowing the owner
probably never heard the term anal sacs before. “Barkley has
an anal sac infection. See how swollen and inflamed it is next to
his anus. In fact the abscess is nearly ready to break through to
the surface of the skin. We’ll need to open this abscess and allow
the infection to drain, and then we’ll flush it, check the other
anal sac, and send him home on antibiotics. Warm compresses for a
few days will speed up the healing, too.”
Few topics raise
dog owners’ eyebrows (and lower dogs’ tails) faster than the subject
of anal sacs. Often called anal glands, these two small
repositories of foul smelling material technically are not glands at
all. Rather they are sacs or pouches lined with cells whose job it
is to continually produce an oily semi-liquid substance that is
stored within the sac. It accumulates like water in a reservoir
until pressure on the sac forces the contents through a narrow
opening just inside the anus. Whenever I describe these unpopular
structures to the dog owner, invariably I’m asked “What the heck
are they for?’ For a credible response I draw on my extensive
knowledge of comparative anatomy, pathology, microbiology and
biochemistry and respond, “I have no idea”. |
WHAT ARE THEY
Anal sacs are small paired pockets located between the internal and
external anal sphincter muscles, one on each side of the anus at the
4 and 8 o’clock position. The sac empties through a short and
narrow duct to the surface near the edge of the rectum and skin at
the anus. Each sac is lined with abundant sebaceous (oil) glands
and numerous apocrine (sweat) glands. The secreted substance is a
semi-oily, brownish fluid that packs an odor strong enough to gag a
maggot!
WHAT THEY DO
One study indicated that anal sac disorders affects about 12% of
dogs. There are a number of theories why dogs, cats, skunks, and
other mammals have anal sacs and what possible use they may have.
One theory states that anal sac contents, when excreted with the
passing stool or by anal sphincter muscle contraction, act as a
powerful territorial scent marker somewhat akin to humans posting a
No Trespassing sign. Another theory states that the anal sac
material lubricates hard stool, which makes passage easier. Humans
do not have anal sacs. It’s bad enough that some humans get
hemorrhoids, which are dilated, irritated blood vessels at the anus;
luckily, dogs do not get hemorrhoids. |
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CAUSES OF ANAL
SAC PROBLEMS
There are no predictable antecedents to painful anal sac disorders.
Infections, obstruction and subsequent overfilling (called
impaction), and rupture with drainage through the perianal skin are
the most common clinical presentations. Anal sphincter muscle
dysfunction, enlarged anal sacs that are not compressed properly by
the anal sphincter muscle, hypersecretion from the anal sac lining,
obstructed or constricted anal sac ducts all may be predisposing
circumstances for anal sac problems.
IMPACTED ANAL
SACS
 Some dogs may be born with very narrow channels that lead from the
sacs to the edge of the anus, thereby obstruction the flow of anal
sac material. Acquired damage to the duct can occur when perianal
infections, trauma, allergies and inflammation compress or obstruct
the narrow channel leading from the sac to the surface. For unknown
reasons some dogs produce a thick or dry material from the sac
lining which makes passage of the material through the narrow ducts
impossible.
AGE/BREED
CONSIDERATIONS
There is no age or sex predisposition to anal sac pathology.
Uncommon in large breeds, infections and impactions are often
experienced by small breeds such as Toy and Miniature Poodles,
Chihuahuas, and Lhasa Apsos. Cocker Spaniels, Basset Hounds, and
Beagles rank high on the list of breeds affected by anal sac
difficulties.
DIET
Some groomers and animal health care workers believe feeding a diet
rich in fiber aids in emptying the sacs. The pressure of the firm
stool against the colon wall near the anus may help to express the
anal sac contents. Dogs that have an existing problem such as
infection or obstructed ducts, though, probably won’t respond to
dietary changes; modifying the diet with more or less fiber yields
inconsistent benefits.
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GROOMERS
There is a difference of
opinion regarding routine expressing of the anal sacs. For example,
veterinarian Mark Thompson in his presentation about anal sacs in
Current Veterinary Therapy XIII,
 suggests routine manual expressing
of the anal sacs should not be done in a normal dog with no
anal sac issues. Many groomers make it a matter of routine, though,
to express the anal sacs
of their dogs. Certified Master
Groomer Sherri Glass, for example, has been grooming dogs for 14
years and has taught grooming for 5 years at Cornerstone Dog
Grooming Academy in Clyde, OH. She relates, “I teach students to
empty anal glands on all small dogs, about 20 pounds or less in
size. We also do any size dog at owners request. If dog owners
would meet their dogs nutritional needs with high quality food, keep
them at proper weight, and provide plenty of good exercise, most
dogs would not have to have the anal sacs expressed.” Mr. Jeffrey
Reynolds, Director of the National Dog Groomers Association of
America says “In states were it is legal for groomers to express
anal sacs, many groomers express them externally only either
as a part of the grooming procedure or at the owners request. When
 there is evidence that the sacs are impacted, then they are not
expressed and the owner is advised to bring the dog to the vet.”
HOW TO RECOGNIZE
A PROBLEM
There is an 88 percent chance the thought of anal sacs will never
even occur to you. However, if your dog is one of the 12 percent
that scoots his rear bumper along the carpet, frequently turns to
lick or bite at the base of his tail or anal region, or displays
discomfort when passing stool, it would be advisable to make an
appointment with the veterinarian. If left untreated, anal sac
impactions, infections and abscesses can be a reoccurring nuisance
for your dog so be proactive about an evaluation if your dog
displays any discomfort in the tail or anal region.
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