Fair warning: The subject of this column really stinks.
Clients have asked me about anal sacs my entire veterinary career. What are they?
Dogs and cats both have anal sacs, located next to the anus at about 4 and 8 o’clock. They are two small pouches with ducts that lead to the rectum.
Anal sacs fill with secretions from the anal glands. These secretions have a distinct odor, actually an awful smell for us humans.
They are typically secreted when a dog or cat has a bowel movement and the stool puts pressure on the anal sacs and then the secretions move down the ducts onto the feces.
The secretions contain pheromones, which are substances that are secreted outside the body and affect the behavior or physiology of another individual of the same species.
The anal sac secretions produce a scent that marks your dog’s territory and identifies your pal. The scent tells other dogs, among other things, your dog’s sex, health and approximate age.
These pheromones give your pal an individual “scent signature” to their feces. Thus, dogs sniff each other’s feces and hind ends as a means of socializing. Who knows? To them it may have the scent of Chanel N°5.
So why do these anal sacs need to be emptied by your veterinarian? Some dogs — such as toy breeds and overweight dogs — are more prone to need to have their anal sacs emptied.
This may be due to inherited defects in the anal sac ducts in small breeds. Being overweight in any breed doesn’t allow the anal sacs to completely empty because excess body fat in the anal area reduces the pressure applied to the sacs while passing feces.
Dogs may also have moist dermatitis, acute or chronic skin infections, be in heat (estrus), or have a change of diet affecting anal sacs emptying. Diarrhea often causes the anal sacs to empty incompletely because the stool is not formed.
When the sacs become overly full they cannot empty on their own. Dogs frequently “scoot” on their backsides, rubbing their bottoms on the ground, when their anal sacs are full. Scooting is their attempt to empty their full anal sacs on their own, which doesn’t work and can be painful.
Dogs with full anal sacs may lick at their anal area, abruptly sit down, cry when pooping, have a bad fishy odor or suddenly turn their heads to look at their rear end.
If you supplement a dog’s diet with fiber, it will make their stools more formed and help express the anal sacs naturally. You can use pumpkin (canned and unseasoned), Metamucil, sweet potatoes or bran. Your veterinarian can tell you the amount of each of these for your dogs’ weight.
Your veterinarian also can provide you with probiotics, which work to aid your dog’s digestive process. Probiotics are available from local pet stores or Amazon, as chews or in powder form that can be added to your dog’s food.
When anal sacs don’t empty fully, the secretions get thick and can plug the ducts so no secretions will be able to empty though them. The anal sacs then can get infected, abscess or rupture.
Your veterinarian can flush and fill the infected anal sacs with medications, give NSAIDS for pain and swelling, and provide oral antibiotics if needed.
Sometimes, anal sacs must be surgically removed if they are chronically infected and/or have cancer. This surgery is complicated and best done by a board-certified veterinarian surgeon.
If your dog or cat has a fishy odor, a swelling next to their anus, cry when they poop, have constipation, have blood or pus in their feces, pain, or have a swelling with an opening next to their anus, a trip to your veterinarian is in order.
Groomers typically perform external anal sac expression by putting pressure on the skin of the dog next to the anus over the anal sac. This will partially express secretions out of a healthy anal sac.
Your veterinarian empties the anal sacs completely by inserting a lubricated, gloved finger into the anus and manually squeezing the anal sac. At this time they also palpate the anal sac for masses and check the secretions for infection, impaction and blood.