Dogs have two small glands, referred sometimes as anal sacs, located either side of their anus, and it is not uncommon for these glands to become blocked. Anal gland blockage is usually resolved easily, but it may recur and if left untreated it can lead to infection. Less frequently, dogs can suffer from more serious anal gland problems, so it is always worth taking your dog to the vet if they are showing signs of a problem in this area.
What are anal glands and what do they do?
The anal glands, also called anal sacs, are two glands positioned at four o'; clock and eight o'; clock relative to the anus as shown in the animation below. Each gland has a small duct that opens into the anus.
Animation of normal anal sac structure and anatomy in the dog
The anal glands are filled with a thick strong-smelling liquid that has a distinctive 'fishy' odour. Normally, when a dog empties their bowels, a small amount of this liquid is deposited on the outside of the dog's faeces. The scent lasts a long time and it is one of the ways that dogs mark their territory and leave each other 'messages' by smell. Occasionally, a dog might also empty their anal glands spontaneously when stressed or nervous.
Animation of natural anal sac emptying
Anal gland blockage
It is very common for dogs to have a problem with their anal glands emptying. This might happen because your dog's faeces are too loose to express the anal glands normally, or because the ducts are inflamed and blocked. When the anal glands do not empty properly, they become overly full and this can be uncomfortable for your dog.
Animation of anal sac swelling
If your dog has blocked anal glands, you may see them 'scooting' their bottom along the ground, licking the area under their tail excessively, or showing signs of discomfort or pain. For dogs showing these signs, it is best to take them to the vet, who will examine the anal glands and empty them if necessary. One technique for emptying the glands is shown here:
Animation of an emptying technique
If your dog's anal glands become blocked repeatedly, your vet may advise that you increase the amount of fibre in their diet to make the faeces more bulky and encourage normal emptying.
Anal gland infection
Sometimes, dogs will develop an infection in their anal glands. This can happen when the glands have not been emptying properly for a while and so bacteria have built up in the fluid. If the infection is left untreated, an abscess can develop where the gland becomes full of pus. This can be very painful and it will require veterinary treatment.
Animation of abscess in the dog
If the infection is not treated, the pressure may build up until the abscess bursts through the skin, releasing the pus and blood. This may make your dog more comfortable in the short term as the pressure is not so painful, but the infection will still require veterinary treatment.
Animation of anal sac fistula
The treatment for anal gland infection depends on the severity and your vet will be able to advise on what is best to do. The condition may resolve simply with a course of antibiotics alongside painkillers if necessary, but in some cases the anal glands may need to be flushed out under a sedation or general anaesthetic. In some cases, your vet may instil topical treatment into the anal glands as shown in this video:
Animation of the medical treatment
Anal gland surgery
For dogs who experience serious anal gland problems, surgery may sometimes be required. It is possible to remove the anal glands surgically, but the anal area is delicate and there is a small potential risk of complications with continence after the operation. If surgery is a possibility for your pet, your vet will talk you through the risks and benefits and help you make the best decision.
Anal gland surgery is also sometimes advised for dogs who develop more serious problems such as anal furunculosis (a condition where the skin around the anus is chronically ulcerated and inflamed) or anal gland tumours. However, anal gland tumours can be malignant, and if a tumour has already spread, your vet may suggest that surgery will not be in your pet's best interests.
If you have questions and you'd like to reach out to us, you can call us directly at (925) 744-6421, or you can email us at [email protected].