One of the most common problems small animal vets see in dogs, almost daily, is anal gland trouble. Although cats have anal glands too, they rarely cause trouble.
All dogs have two anal glands (or anal sacs) situated just inside the rectum, one on each side. The cells which line the glands produce a foul-smelling substance which dogs use as a territory- marking device. When the dog passes faeces, the anal glands get squeezed and the scent is deposited as well. The normal anal gland is about the size of a pea in a small dog or a grape in a larger dog, depending how full it is. The anal gland secretion travels down a short tube or duct to enter the rectum. It can be liquid or more like a paste in texture.
When everything is working properly, the anal glands empty naturally and cause no trouble. Unfortunately it is quite common for the glands to become over-full or for the duct to become blocked, and then they cause discomfort. When they do not empty naturally, they are described as impacted and the condition is called anal gland saculitis. The dog will then try to lick at the area or will “scoot” their bottom along the ground in an attempt to relieve the irritation. This may well make things worse and allow infection to enter, leading to an abscess. If things get this bad, the main sign will be pain, or a blood-stained discharge if it bursts.