Anal sac issues: Butt seriously, folks

When I was young, our springer spaniel bolted from our yard and was hit by a car.  The car wasn’t going fast, but the impact was enough to fling poor Nipper from the road onto our lawn. I stopped screaming when I realized that my beloved pup was more shaken up than hurt, and then I noticed it: an unidentifiable foul odor.  It wasn’t until I was in veterinary school that I found out what that stench was:  essence of anal gland.

Although cats have these glands, too, our feline friends fortunately are not afflicted with anal gland problems to the degree that dogs are.  But you may assume that everything I discuss about this topic also applies to cats.

The anal sacs are the reservoirs for the secretion of anal glands, which are located on both sides of a dog’s anus at approximately four and eight o’clock.  The sacs contain a substance that ranges in consistency from a paste to a liquid and is normally light to dark brown.  The contents of the sacs are emptied through ducts located on each side of the anus, usually during bowel movements or when a dog is nervous or frightened.  The probable function of the secretions is to mark territory and to distinguish an individual dog from others of his species. 

Many in the pet-owning population already know the facts about these sacs.  If this is new knowledge for you, consider yourself lucky: It means you haven’t had the annoyance of dealing with the problems these pesky little vestigial structures can cause in your dog. 

We see three categories of anal sac abnormalities, sometimes concurrently:  impaction, infection, and abscesses.   All of those conditions cause varying degrees of discomfort or pain.  The pet owner might notice the dog licking or biting near or under his tail, and often that area will be red and tender.  Also common is the “butt scoot,” in which the dog sits with his hind legs extended straight forward and propels himself ahead with his front legs, scraping his anus along the ground (or your carpet).  That’s just his way of trying to relieve the irritation (or pressure, if the sacs are impacted).  Some dogs will chase their tails, and some will strain to defecate. If the sacs are infected or abscessed, the owner may see blood or pus on the perianal area, on the floor or in the dog’s bedding.  And there’ll probably be a pungent odor.  Some dogs are depressed and in significant pain, and will stop eating. 

With impaction, the normally thin secretion becomes so thickened that the sacs don’t express properly.  Expressing impacted anal sacs is like squeezing dry, congealed toothpaste from a partially blocked tube — challenging!  To facilitate emptying the over-packed sac, I take a tiny tube and place it in the duct.  I then infuse an oily antibiotic preparation into the sacs and express them.  The oil thins and lubricates the secretion, allowing easier evacuation of the sludge.

 

Infected anal sacs get the same antibiotic flushing as impacted ones, after which more antibiotic is infused into the affected sac and allowed to remain.  We recheck and re-infuse the anal sacs weekly until they’re normal.   Although we can deal with infected ears by taking swabs, staining them, and looking at them under the microscope to help us choose the correct medicine, doing cytology and cultures for anal sac infections is a waste of time and money.  Trial and error is the rule here.   

Anal sac abscesses can be treated in the same way as infections, but sometimes they require anesthesia and surgery to deal with complications such as tissue death, severe swelling, and pain.

 

I wish oral antibiotics were more helpful for these infections, but it ain’t so.  We tend to use them as a last resort in cases where conventional treatments have failed, for abscesses, or when we see blood in the anal sac contents.  Steroids by injection or by mouth seem to work best, especially when used in conjunction with flushing.  Sometimes sitz baths in warm water help alleviate the discomfort.

We don’t know all of the causes of anal sac problems, but there does seem to be an association with allergies (environmental as well as food), obesity, a low-fiber diet, lack of exercise, and gastrointestinal disease.  Genetics may also play a role.  Diagnosing the cause can be difficult, but for chronic recurring anal sacculitis, environmental allergy testing or a food allergy trial using a prescription hypoallergenic diet may be warranted.

Other than treating for allergies, how can these butt maladies be prevented?  Again, trial and error rules the day.  Weight loss and increased exercise may help.  Switching to a high-fiber diet or adding fiber such as pumpkin, bran cereal, or Metamucil to food has helped some of our patients.

Often, in spite everything we’ve tried, both the pet and his people are plagued by recurring anal sac disease and multiple trips to our office.  I often joke (though I doubt the pet owner is much amused) that the purpose of anal sacs is to make money for veterinarians.  If your buddy is continually scooting and you’re tired of dealing with the inconvenience, the expense, and an unhappy pet, consider the one treatment that’s a permanent cure: surgical removal of the sacs.