Why Do Dogs Have Anal Glands? 5 Fascinating Functions
If you're curious about why dogs have anal glands, you'll be delighted to learn that anal glands in dogs carry a variety of important functions.
Dogs are fascinating creatures boasting a vast array of unique features that sets them apart from other animals. One such feature is a dog's anal glands.
Anal glands in dogs aren't there just for decoration. These small, sac-like glands located on both sides of your dog's bottom, may seem rather insignificant, but at a closer insight, they serve several vital purposes in your dog's life.
As a product of evolution, your dog's anal glands play important roles for the purpose of communication, identification, and also as a defense mechanism.
What Are Anal Glands in Dogs?
A dog's anal glands, also known as anal sacs or scent glands, consist of small specialized structures present in the dog's body with the purpose of producing and releasing substances.
These sacs are located on both sides of your dog's bottom, more specifically at the 4 o'clock and 8 o' clock position.
A dog's anal glands are known for producing a special fluid that is expelled through small ducts.
The consistency of the fluid may vary from watery to creamy to thick or pasty and the color may vary as well ranging from cream to brown.
So what's the purpose of anal glands in dogs and their secretions? Let's discover!
Dogs have anal glands for many good reasons!
1.Exchange of Business Cards
Your dog's anal glands are lined up with specialized cells that are responsible for producing a fluid that has a unique blend of scent molecules.
The composition of this fluid varies from one dog and another making it the canine equivalent of a business card with lots of personal information.
This explains a dog's fascination with sniffing each others' butt area when they meet. It's as if they were exchanging business cards as a way of getting to know each other.
Interestingly, the composition of this fluid is prone to changing from one day and another, which explains why dogs don't just sniff each other as a one-time ordeal.
Instead, dogs will sniff each others' bottoms on multiple occasions, on every encounter, even on a daily basis.
What information do dogs gather by sniffing each other's bums? There is belief that dogs may learn many interesting things about each other including gender, health status, and even their emotional state.
Now you understand why your dog's fixated on sniffing other dog's butts!
2. Placement Of "Business Cards"
Dogs may also leave their "business card" information around courtesy of the strategic deposition of feces.
Basically, every time your dog passes stools, muscles around his bottom squeeze some fluid out which anoints the feces with a few drops of a substance produced within the dog's anal sacs.
Other dogs then come along and sniff this material, thus being informed of who passed the stool, explains veterinarian Dr. Ivana Crnec.
In this case, it's as if your dog is placing business cards around while other dogs spend time reading them, helping keep the neighborhood dogs well-informed about the other dog's presence and/or territory.
Anal glands secrete fluid when dogs produce solid poops
3. Raising a Red Flag
On top of being used for the exchange of personal information, a dog's anal gland secretions can help raise a red flag when a dog is particularly frightened.
A classical example is the dog who is frightened at the vet's office and suddenly empties his anal glands under the form of a spray with an intense, foul odor.
In this case, the emission allows the dog to alert other dogs of potential danger, which can cause other dogs to become concerned.
Donovan (1967) has tested the hypothesis that dogs express their anal glands for the purpose of escaping threatening restraint.
He smeared a dog's anal gland secretion on plastic gloves and presented them to puppies and adult dogs to sniff.
The puppies showed no response, while the adult dog “recoiled and appeared apprehensive."
Dogs may express their anal glands when frightened
4. Advertisement For Dating
Interestingly, when female dogs are in heat, their anal glands produce trimethylamine-rich secretions.
These secretions, with their distinctive fishy odor, appear to be attractive to male dogs.
Did you know? Apparently, the special color of the hairs surrounding a dog's anal gland areas also plays also an important role in improving the efficacy of the associated chemical signals.
5. Lubrication For Passage of Stools
Another proposed function of the secretions produced by a dog's anal glands is to provide lubrication so to facilitate the passage of feces.
Male Versus Female Anal Glands in Dogs
The anal glands of male and female dogs are not created equally. Rather, they exhibit sexual dimorphism, meaning that there are differences between the anal glands of male and female dogs.
In adult males, the glands surround the dog's bottom in a circle within the subcutaneous tissues, whereas, in adult females they form spaced islets within the subcutaneous tissues.
This difference is what makes male dogs 5 to 6 times more prone to the formation of tumors in this area.
Did you know? In male dogs the anal glands increase in size over the years. In old male dogs, their diameter is 3 to 4 cm.
Problems With Anal Glands in Dogs
Generally speaking, dogs that tend to pass softer stools (due to dietary indiscretions or medical issues) are more likely to develop anal sac issues.
This is because the softer the stool, the less power it has to naturally express the sacs. It is also postulated that anal sac conditions are more common among dogs that are not on regular exercise regimens, explains veterinarian Dr. Crnec.
The most common sign that indicates anal sac issues is increased licking or scooting. Some affected dogs simply jump up from a resting position as if they have been startled or felt a sudden pain.
Other symptoms include the dog biting its rear end, constipation, difficulties while passing stools, bad smell, itching, snapping and growling if you try to touch the dog's tail and anus.
Dachshunds, Retrievers and Spaniels are particularly prone to anal sac problems. The risk of anal sac problems is particularly high in small dogs suffering from obesity.
References:
- Janssenswillen S, Roelants K, Carpentier S, de Rooster H, Metzemaekers M, Vanschoenwinkel B, Proost P, Bossuyt F. Odorant-binding proteins in canine anal sac glands indicate an evolutionarily conserved role in mammalian chemical communication. BMC Ecol Evol. 2021 Sep
- Donovan CA. Canine anal glands and chemical signals (pheromones). J Am Vet Med Assoc. 1969 Dec 15;155(12):1995-6. PMID: 5392169.
- Atoji Y, Yamamoto Y, Komatsu T, Suzuki Y, Tsubota T. Circumanal glands of the dog: a new classification and cell degeneration. Anat Rec. 1998 Mar
- Current research in canine and feline pheromones, Emmanuel Gaultier, 2003, Veterinary Clinics of North America: Small Animal Practice
Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice or behavioral advice. If your dog is acting sick or aggressive please consult with a qualified professional for proper diagnosis and treatment.
