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Anal Glands

Randy Walker DVM

What Are The Anal Glands?

The anal glands (more properly termed the anal sacs) are two sac-like structures located just under the skin near the anus. These sacs periodically fill with a thick, foul smelling secretion known as anal gland secretion (or anal sac secretion). Under normal circumstances a small amount of this secretion (discharge) is expelled from the gland each time the pet defecates (meaning to "go to the bathroom" or "produce stool")

What Is The Difference Between The "Anal Glands" And The "Anal Sacs?"

Technically speaking, "anal sacs" is the proper term for the structures which house the anal gland secretion while the "anal glands'' are the microscopic glandular structures, lining the inside of the anal sac, which produce the secretion itself. In common usage, however, the terms "anal sacs" and "anal glands" are used interchangeably. Since most of our clients are accustomed to referring to these structures as "anal glands" this is the term we often use in the veterinary clinic.

Are The Anal Glands A Normal Part Of My Dog's Anatomy?

Yes.

Does My Cat Have Anal Glands?

Yes.

Do People Have Anal Glands?

No.

What Is The Function Of The Anal Glands?

The anal glands have no known function in the modern world. They are "vestigial" organs like your appendix) meaning that they once had a function but as the dog and cat evolved, the anal glands lost that function. The best theory is that dogs once used the pungent smelling anal gland secretion to mark their territories in the wild. Wolves and other wild cousins of the dog are known to do this. Also, dogs will occasionally express (meaning to squeeze secretion out) their anal glands when they are frightened, so it is thought the secretion could be intended to have a defensive repellent function.

Can My Dog's Anal Glands Sometimes Become Diseased Or Have Other Problems?

Yes.

What Are Some Of The Diseases Or Problems That The Anal Glands Can Have?

The main problems the anal glands can have are (1) impaction; (2) infection and abscess; (3) rupture; and (4) tumors.

What Is "Impaction" Of The Anal Glands?

This is "plugging-up" or "stopping-up" of the anal glands, with normal secretion. Sometimes the outlet (called the duct) of the anal gland becomes stopped-up and the gland fails to empty properly. This usually leads to discomfort (from the accumulating pressure) and will sometimes lead to infection.

How Can I Tell If My Dog Has Impaction Of The Anal Glands?

Though the signs will vary from case to case, common signs are: (1) scooting on the rear end; (2) licking the region around the anal glands; (3) reluctance (sometimes) in defecating (often resembling true constipation); and (4) discomfort (sometimes) when the area is touched. Occasionally, a dog can have an impaction and not show us any of these signs. Also, these symptoms (scooting, licking the rear area, etc.) can be signs of other problems on occasion too (such as worms, skin infection, stool. adhered to the fur, etc.) so it's important that we examine the patient to determine exactly what the problem is.

How Is Impaction Of The Anal Glands Treated?

In uncomplicated cases, treatment usually consists of digitally (meaning to use the fingers) squeezing the glands to help them express.

Briefly, How Do You Express The Anal Glands?

There are two common methods which can be referred to as the "external" and "internal" methods. With the external method we express the anal glands by placing a paper towel (or something similar) against the glands (which can be felt with the fingers - they feel like "grapes" under the skin) and gently pressing on them to get them to express. With the other method of expressing the anal glands, called the "internal" method, we first put a latex exam glove on and lubricate the index finger with KY jelly. Then the index finger is gently inserted in the anus and we isolate the gland between the index finger and thumb. Then we gently squeeze the gland from both sides (inside and outside) to express the secretion. I personally prefer this method because (for me at least) I can express more of the secretion from the gland than with the external method.

Can My Groomer Express My Dog's Anal Glands?

Yes. Of course this is up to the individual groomer, but many dog groomers do provide this service.

Can I Learn How To Express My Dog's Anal Glands?

Yes. Although most people have either the veterinarian or the groomer do this, you can learn to express your dog's anal glands at home. Your regular vet will be glad to show you how.

Briefly, Describe Infection, Abscess, And Rupture Of The Anal Glands.

Infection of the anal glands is not uncommon especially with chronic impaction. When one or both of the glands become(s) infected they often will rupture to the outside and drain, similar to any other abscess. This can be quite painful when it occurs, but fortunately most patient's anal glands will heal in a short time (several days).

Briefly, How Do You Treat Abscess And Rupture Of The Anal Glands?

In uncomplicated cases we treat this by cleaning out (flushing) the ruptured anal gland with antiseptic solution and placing the patient on antibiotics when indicated. After the ruptured gland has healed over we express it periodically to try to insure that it's not becoming impacted again.

Do Some Dogs Have Chronic Problems With Their Anal Glands?

Yes.

What Can Be Done For The Patient Who Has Chronic Problems With The Anal Glands?

In chronic cases the treatment of choice is usually to remove the glands surgically in an operation called an anal sacculectomy. Since the anal glands are vestigial organs, the dog with chronic anal gland problems is better off without them.

What Factors Will Predispose One Patient To Have Problems With The Anal Glands More Than Other Patients?

The main factors which predispose patients to have problems are (1) small body size and (2) obesity. Dogs under 20 lbs. have a higher incidence of anal gland impaction and other anal gland problems than larger dogs. The smaller the dog is, the more chance of anal gland problems. Tea cup poodles, Chihuahuas, and Pomeranians have an unusually high incidence of impaction. As with all generalities, of course, we will see exceptions with many small dogs never having any anal gland problems and some large dogs occasionally having severe problems. Overweight dogs also occasionally have a mechanical problem with getting the glands to express well.

What Role Does Diet Play In The Health Of The Anal Glands?

This is controversial. There is some evidence indicating that a diet higher in fat will cause more anal gland secretion and thicker secretion and therefore more potential problems but this is not certain. Also, some have advocated a high fiber diet to increase the frequency and the bulk of the stools, thereby stimulating the glands to express more often. Here again, no studies as of yet have conclusively proven this to be of benefit, so dietary approaches are strictly on a "trial basis".

How Can I Lower The Chances Of My Dog Having Anal Gland Problems?

You should have your dog's anal glands expressed (or express them yourself) as often as needed. Some dogs never need the anal glands expressed while some need them expressed as frequently as every couple of weeks. On the average, dogs under 15 lbs need the anal glands expressed about every couple of months. It's a good idea to have your groomer express the anal glands along with routine grooming (or have us do it).

Can My Cat Have Problems With The Anal Glands?

Yes but this is very uncommon.


- Randy Walker DVM
Sun Lakes Animal Clinic
May 14,2004



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Titlebar Image: The Gentle Doctor, 1937-38 by Christian Peterson (U84.179) - Iowa State University