What are anal glands?
Anal glands are two sacs about 5mm long situated either side of the anus at the 4 o’clock and 8 o’clock positions. The lining of the sac is made up of secretory cells. Each sac has a small duct which leads to a tiny opening just inside the anus.
What is their function?
A pungent secretion normally accumulates in the anal sacs. This secretion is used as a marker and in the wild is used to mark territory. In the domestic cat or dog they have little or no use, although the sacs are often emptied when the animal is frightened. Emptying usually occurs during defaecation as this process has a squeezing effect on the sacs.
The two major problems encountered commonly in practice are impaction (blockage) and infection. Neoplasia (cancer) of the sacs is also possible but is quite rare. Impacted or infected sacs are often painful and the irritation causes the animal to “scoot” its bottom along the ground and to lick or chew in the area.
Blockage or overfull sacs occurs if the normal emptying process fails. This can be due to diarrhoea (reduced squeezing effect as mentioned above), poor anatomy such that the sacs have difficulty emptying normally and diet may play a part especially if the stool is not properly formed.
Uncomplicated impaction can be treated by manual emptying of the sacs by your vet. This may mean squeezing the sacs by pressing from the outside or by using finger pressure from within the rectum. In either case the sac contents empty via the ducts into the anus and material is wiped away. Be careful that none of the secretion gets on you – it smells! In a small number of animals this treatment may be required on a regular basis. Bulking out the stool might help in these recurrent cases e.g. by using bran or changing the diet. Ask your vet what he or she recommends.
A bacterial infection often presents in much the same way as impaction but the condition may progress to a situation where an abscess forms in the sac and the whole area becomes inflamed and very painful. This can be quite sudden in onset and can lead to a lot of worry both to the dog and the owner. Washing the area in warm water may encourage the abscess to burst but emptying as described above is often necessary. Antibiotics are usually prescribed and these may be infused into the affected sac via the duct and/or given by pills or injections.
Recurrent and problem cases of anal sac disease may warrant surgical removal. This requires general anaesthesia and the sacs are removed via two small incisions either side of the anus. The skin is stitched and although the patient may be uncomfortable for a few days the surgery provides relief from the problem quickly. Complications are unusual and surgery is of great benefit in recurrent cases.