Anal Sac Disease
What are anal sacs?
The anal sacs (commonly referred to as anal glands) are paired sacs, which sit on either side of the anus, at approximately 4 and 8 o’clock. They routinely fill with a smelly fluid used naturally to scent mark. Most dogs empty their anal sacs periodically while toileting but can also empty them suddenly if scared or stressed. Healthy anal sac contents can be yellow, brown or grey, and can vary from liquid through to a putty-like consistency. The smell is often very strong and described as fishy.
What is anal sac disease?
Sometimes the anal sacs become impacted, inflamed or infected. In these cases, we usually need to intervene, manually emptying the sacs and sometimes giving additional treatment. It is not understood why some dogs are so prone to anal sac problems, but they seem to be more common in dogs who are inactive, overweight, have skin disease, have poor diet, have variable stool consistency, or in female dogs who have been in season.
Dogs with anal sac disease often lick or chew at their back end, sometimes obsessively. They may rub or scoot their back end on the floor, and some struggle to sit down comfortably. You may notice them straining to toilet, blood around the back end, or discharge in the case of infections
Most anal sac disease can be identified on clinical examination. If your dog is very sore or dislikes the vets, they may need sedation to allow proper examination. To fully assess the anal sacs, the vet or nurse will need to insert a gloved finger into the rectum just past the sacs, approximately 2-3cm in.
Anal sacs can become impacted by dried out material or inflammation around the gland opening. Often, in a cooperative patient, impactions can be cleared manually by expressing (emptying) the sacs. Sometimes, it is helpful to express the sacs again 24-48 hours later.
Anal sacculitis refers to inflammation of the sac and can occur alongside impaction or on its own. Emptying the sacs is often very painful, and the contents may contain blood. In mild cases, they can be managed medically with anti-inflammatories and antibiotics. However, in more severe cases it can be beneficial to flush the sacs under sedation or anaesthesia. Sometimes, this is the only way they can be emptied.
Anal sac infection often leads to abscess formation. This causes a large swelling and can be extremely painful until the sac is lanced, or bursts of its own accord. Antibiotics may need to be prescribed, and a swab may be taken for culture and sensitivity testing, to ensure we use the most appropriate antibiotic.
Once anal sac disease has been identified, regular checks of the sacs are advisable to prevent recurrent episodes of impaction. Reducing risk factors can help, such as weight loss and managing skin disease. Anecdotally, increasing the fibre content of the diet (using specialised products such as fibre+, or home remedies such as bran powder, boiled sweet potato or Weetabix) can also reduce recurrence.
Patients with anal sac disease that is not resolving, or is recurring regularly, may be candidates for surgical anal sacculectomy. This means removal of the anal sacs and does not have any long-term impact on the dog. There are some risks associated and the longer problems have been present, the more technically demanding the procedure is due to increased inflammation and scar tissue.
The prognosis for the majority of dogs with anal sac disease is very good. We do not always understand why impaction, sacculitis or abscesses occur but, in most dogs, they are isolated incidents that resolve rapidly. Some patients are particularly prone to anal sac problems, and it is much harder to get under control. In these cases, anal sacculectomy can offer a significant increase in quality of life.