If you've ever caught a whiff of something distinctly fishy near your dog's back end and wondered what on earth is going on, you're not alone — and no, it's not something they ate. That smell has a specific, very findable source, and once you know what it is, it stops being a mystery and starts being manageable.
The Real Source
Tucked just inside your dog's anus are two small anal glands, each about the size of a pea. Normally, a little of the oily, pungent fluid they produce releases naturally whenever your dog has a bowel movement — it's how dogs mark territory and share information with each other, sniffed out during those long hello-greetings at the park. Most of the time you never notice it. But when those glands don't empty fully on their own, the fluid builds up, thickens, and starts to smell stronger — often described as fishy, musky, or metallic.
Why It Happens
Some dogs' glands empty perfectly with every bowel movement for their whole lives. Others — often smaller breeds, dogs with softer stools, or dogs carrying a little extra weight — are more prone to buildup. Allergies, low-fiber diets, and general inflammation can all make it worse, since firmer stool is what naturally applies the pressure glands need to empty on their own.
What to Watch For
A little fishiness after they've had a stressful moment (a vet visit, a startle) is normal and fades fast. It's worth paying closer attention if the smell lingers for days, if your dog is scooting or licking back there more than usual, or if you notice swelling or redness. Those are signs the glands may be impacted or heading toward infection, and a trip to the vet is the right next step.
The Good News
For most dogs, this is a manageable, ongoing bit of maintenance rather than a medical emergency — a bit like clipping nails or brushing teeth. Diet, weight, and regular checks can keep it from ever becoming a bigger issue. It's exactly the kind of unglamorous, unspoken dog-parent problem we started Nothing to Sniff At to solve.