What are blocked anal glands in dogs

Every dog has a pair of anal glands. They're small sacs, about the size of a blueberry, and sit just inside the anus (bottom). If you think of the circle of the anus as being a clock face, the anal glands are located around 8 o’clock and 4 o'clock. Dogs’ anal glands contain a strong-smelling liquid. If you’ve smelt it, you’ll remember it — the odour is distinctively fishy and unpleasant. The glands should empty when the dog defecates and then re-fill in a constant cycle. This smelly discharge is important in canine scent communication.  

Any dog of any age, size, or breed can get blocked anal glands. However, there are a few reasons why some dogs are more prone to this condition:  

• some dogs are born with very narrow openings to the anal glands, which means they become more easily blocked.  

• bowel issues leading to soft stools, such as chronic diarrhoea, will mean the glands don’t empty fully (or at all), leaving them prone to becoming impacted, blocked or infected.  

• dogs who are overweight are more likely to have problems, as obesity is associated with weaker muscles around the back end.  
  
  
  
  Written by Dr. Mariella Roberts, Veterinary Surgeon, Animal Trust Vets CIC | Published March 2025 | Review date March 2027 | This advice is for UK pets only