If your dog is scooting across the carpet, licking obsessively at their backside, or you've caught a whiff of something distinctly fishy, their anal glands are probably the culprit. It's one of those topics that makes owners a bit squeamish, but understanding it can save your dog a lot of discomfort and you a lot of vet visits.
Key Takeaways
- What Are Anal Glands, and What Do They Actually Do?
- Signs Your Dog Has an Anal Gland Problem
- Why Do Anal Glands Get Blocked?
- How to Know If It's Serious: Blocked vs Infected
- What NZ Vets Typically Recommend
Here's everything you need to know.
What Are Anal Glands, and What Do They Actually Do?
Anal glands (also called anal sacs) are two small pouches located on either side of your dog's anus, roughly at the 4 o'clock and 8 o'clock positions. Each gland contains a small amount of a strongly scented, oily fluid.
In the wild, this fluid served a few purposes. Dogs would naturally express these glands when defecating, leaving a scent marker on their faeces - a kind of calling card that communicated identity, territory, and even mood to other dogs. It also plays a role in that characteristic bum-sniffing behaviour: dogs are literally reading each other's anal gland secretions as a form of communication.
The problem is that modern domestic dogs don't always empty these glands the way nature intended. When they fill up without being expressed, things go wrong.
Signs Your Dog Has an Anal Gland Problem
Most anal gland issues are obvious once you know what to look for. Common signs include:
- Scooting - dragging their bottom along the floor is the classic sign
- Fishy smell - a strong, unpleasant odour around the rear end (sometimes described as fishy or metallic)
- Licking or chewing at the base of the tail or around the anus
- Discomfort when sitting - shifting position frequently or refusing to sit normally
- Swelling or a visible lump near the anus (this can indicate an abscess)
- Brown or yellowish discharge on furniture or bedding
- Tail chasing - especially if combined with the above
Some dogs get anal gland issues once and never again. Others deal with them chronically. If yours is in the second camp, it's worth understanding why.
Why Do Anal Glands Get Blocked?
Several factors contribute to anal gland problems:
Diet and stool consistency
This is the big one. The anal glands are naturally expressed when a dog passes a firm stool - the pressure of the stool against the glands as it passes through empties them. Soft, loose, or small stools don't create enough pressure to do the job. A diet low in fibre is a common contributor.
Breed
Some breeds are predisposed to anal gland problems. Small and toy breeds (Chihuahuas, Poodles, Shih Tzus, Dachshunds) are particularly prone. The anatomy in smaller dogs often means the ducts that drain the glands are narrower or positioned in a way that makes natural expression harder.
Weight
Overweight dogs are significantly more likely to suffer from blocked anal glands. Excess body fat can physically alter the anatomy around the glands and their drainage ducts, making it harder for them to empty properly. It's one more reason weight management matters.
Anatomy and conformation
Some dogs simply have glands positioned deeper or with narrower ducts than average. This is largely genetic and not something diet or exercise will fix entirely - but it can be managed.
Allergies and inflammation
Chronic skin allergies can cause inflammation in the tissue around the anal glands, which contributes to blockages. If your dog has other allergy symptoms alongside anal gland issues, it's worth exploring whether food or environmental allergies are a factor.
How to Know If It's Serious: Blocked vs Infected
There's a meaningful difference between an anal gland that's just full and one that's infected.
Impaction (just blocked): The gland is full and uncomfortable, but no infection has set in. The secretion becomes thick and pasty rather than its normal fluid consistency, making it harder to express. The dog will be uncomfortable but not in serious pain. This can usually be resolved with manual expression by a vet or trained groomer.
Infection: If a blocked gland isn't cleared, bacteria can multiply and an infection can develop. Signs of infection include redness and swelling around the anus, obvious pain when touched, and sometimes a dark or bloody discharge. The dog may be lethargic or reluctant to move normally.
