What are anal glands and what do they do?

Anal glands (or anal sacs) are two little scent glands sitting just inside your dog's bottom, at roughly four and eight o'clock if you picture a clock face. Each one holds a small amount of strong-smelling fluid. Yes, they're every bit as glamorous as they sound.

Their actual job is scent marking. That fluid is basically a scent ID, which is why dogs are so interested in sniffing each other's back ends. Every dog's smells a little different, so it tells other dogs who's been around. Normally the glands release a tiny bit each time your dog does a firm poo, and you'd never know they were there.

The trouble starts when they don't empty properly. If the fluid builds up, the glands can get full and uncomfortable, then impacted or infected. That's when you see the classic signs: scooting along the carpet, licking or biting at the area, or a sudden strong fishy smell.

Firm, well-formed stools are what naturally press on the glands and keep them emptying, which is one reason diet and fibre come into it. If your dog seems bothered back there, or you notice swelling, blood or a bad smell, get your vet or groomer to take a look. It's common and usually sorted easily, but worth checking rather than guessing.