Smelly Business: Anal Glands!

Anal sac emptying- is this really necessary?!

Anal sacs- the bane of the life of many a cat, dog, owner and Vet! They are commonly known as ‘anal glands’, but in fact this is not strictly correct, since the glands themselves sit within the walls of the sacs.


What are anal sacs and why do our pets have them?

The anal sacs are two small pouches situated either side of the anus. Each sac has a small channel, or duct, which connects the sac to the outside via an opening just inside the anus. The size of the sacs varies depending on the size of the animal and also whether the sacs are full or not, but they typically range from pea-sized to grape-sized.

The sacs are lined by many anal glands which secrete a strong smelling substance, which under normal circumstances is released from the anal sacs through the ducts.

The substance secreted varies in thickness, but most commonly is a fluid. This fluid is released in small amounts when the animal passes normal faeces, and acts to scent mark the faeces.

In this way, cats and dogs are able to mark their territory. This explains why dogs usually greet each other with a reciprocal sniff of the rear end! This behaviour which is alien to us, allows dogs to gather information about and identify other dogs they encounter.

The sacs can also spontaneously empty at times of stress and fear, in the same way as a skunk uses strong smelling anal gland secretions to repel predators.


Why do some anal sacs not empty properly?

The anal glands lining the anal sacs are constantly producing secretions. If the secretions do not empty properly through the ducts, then they build up within the sacs causing anal sac impaction.

Some animals produce particularly thick secretions which do not easily pass through the narrow ducts.

The ducts are located just inside the anus, therefore faecal bacteria can sometimes cause infections and inflammation of the anal sac ducts. This can cause narrowing of the ducts and prevent normal anal sac emptying.

Animals with long term soft motions or diarrhoea will commonly develop anal sac impaction, since the physical passing of a normal, formed motion promotes the normal emptying of the anal sacs.

Overweight or obese animals are more prone to anal sac impaction since their sacs do not empty normally when faeces are passed.

Other causes of anal sac impaction include tumours of the ducts or the anal  glands themselves. Although much less common, we do occasionally see these problems in older patients.


How can I tell if my pet has full or impacted anal sacs?

The most common sign that there may be a problem is ‘scooting’. This is when the dog or cat rubs their anus on the ground repeatedly, or spends more time than usual licking or nibbling their rear end. Owners will sometimes misinterpret this behaviour as a sign that their pet needs de-worming. Anal sac impaction is the most common cause of this behaviour, but there can be other causes, therefore we always recommend you get your pet checked out as soon as possible if they start to display this behaviour. The scooting or nibbling can be so intense that some animals cause damage to the skin around the tail and rear end.

Some owners notice that their pet smells more when the sacs are impacted. This can be due to anal gland secretions leaking out through the ducts from sacs which are under pressure.

Impacted anal sacs are uncomfortable, and therefore some animals may change behaviour, becoming either more withdrawn and off colour, or in the case of cats in particular, occasionally can become aggressive and grumpy.

Cats with impacted anal sacs may find defaecating difficult and uncomfortable, and therefore will sometimes start passing faeces outside of the litter tray.

If anal sac impaction has been caused by infection, then sometimes an abscess can form in one or both of the anal sacs. Similarly, impacted anal sacs are more prone to becoming infected, and can subsequently abscessate. Anal sac abscesses are extremely painful, and the inflammation and swelling associated with them may be obvious to see around the anus. Pets with anal sac abscesses are often off colour and appear unwell, but some may show no obvious symptoms.

If untreated, anal sac abscesses can eventually rupture through the skin, releasing anal gland secretions, pus and blood. This is often the first thing that alerts an owner to the fact their pet has an anal sac abscess.


How can I make sure that my pet has healthy anal sacs?

The majority of pets have normally functioning anal sacs.

Feeding your pet the correct diet to ensure normal, formed faeces is important for maintaining anal sac health. Other problems can lead to chronic, soft motions or diarrhoea, therefore we would always advise getting your pet checked here at the surgery if your pet has this problem.

Overweight pets are more prone to developing anal sac impaction, therefore weight loss in such patients may help.

If your cat or dog starts to display ‘scooting’ behaviour or any of the other signs described above, it is best for you to make an appointment here at the surgery as soon as possible.

Our Vets here can check the anal sacs of your pet for any problems, and can normally very easily empty (express) impacted sacs. We can even teach owners to empty the anal sacs of their own pets, in the case of particularly compliant animals. Understandably, most owners prefer the Vet to perform this particular task!

Some animals benefit from regular, routine anal sac emptying, even if they are not showing signs of a problem. This can help prevent complications such as anal sac abscesses.

If any other problems are found at the time of emptying, for example anal duct infections or anal sac abscesses, the Vet may dispense a course of anti-inflammatories and antibiotics. It may also be necessary to perform a bacterial swab, particularly in cases which are not responding well to antibiotic treatment.

Some anal sacs become so impacted that it is not easy to manually express them. In such cases, it may be necessary to sedate or anaesthetise the animal to allow the anal sacs to be flushed out and treated correctly.

Some pets develop recurrent impactions and abscesses, and in such cases it may be appropriate to consider surgical removal of the anal sacs. Your Vet will discuss this with you as an option, should your pet develop chronic, recurrent problems. All surgical procedures have risks associated with them, and we can discuss any risks and their likelihood fully with you should this be an appropriate option. Surgery would also be appropriate in cases involving tumours of the anal sacs and ducts.

Remember, although not the most pleasant task for all concerned, don’t be embarrassed to ask your Vet to check the anal glands of your pet!