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We have all seen the video of a dog dragging their behind along a carpet, floor, or lawn. Besides being a bit awkward and somewhat embarrassing for their owner, what does this mean? Why do dogs do this? Sometimes it is as simple as a piece of grass or stool that gets stuck to them, and they are trying to release it. However, more often, this indicates a possible issue with their anal sacs.
Anal sacs are small pouch-like structures located between the internal and external anal sphincter muscles on either side of the anus. Each anal sac contains glands that produce secretions, so they tend to fill with fluid as well as skin cells and bacteria. The secretion can have variable color and consistency, and most often, it has a foul, sometimes fishy or metallic smell. It is thought that anal sacs are meant for marking territory, identification, and defense. Anal sacs are emptied with each bowel movement, from the stool pressing against them or from the compression of anal muscles during defecation.
Clinical signs that can indicate a problem with anal sacs include scooting, licking, or biting the perianal area or tail base, discomfort when sitting, painful defecation, swelling on either side of the anus, bad odor, and discharge or draining tracts near the anus. If any of these concerns are present with your dog, it is best to have him or her evaluated. There are other conditions that could also present with some of these clinical signs, so an exam is needed to help differentiate the cause. Conditions to rule out could include urinary diseases such as a UTI, vulvar dermatitis in female dogs, flea allergy dermatitis, rectal prolapse, gastrointestinal parasites, or perianal fistulas.
Your veterinarian will need to do an internal rectal exam to fully evaluate the anal sacs. This will help to determine the state of the anal sacs. Diseases and conditions affecting the anal sacs include impaction, sacculitis, abscessation, and tumors.
Anal sac impaction occurs when the sacs overfill and the contents are retained in the sac instead of being expressed through normal defection. This can cause the area to swell and is often irritating or painful to the dog. Often, this can be relieved with warm compresses and manual expression by the veterinarian.
Sacculitis is when there is inflammation associated with the anal sacs whether just from significant swelling or from infection. This is often more painful than just impaction. Anal sac expression can be done both for therapeutic and diagnostic purposes, and this can require medications to help, such as antibiotics or pain medication. Sometimes, infusion of the anal sacs with antibiotic or anti-inflammatory medication is warranted.
When an anal sac becomes abscessed, infection causes local cellulitis, which sometimes presents as draining tracts through the skin on either side of the anus. Some anal sac abscesses can be medically managed with antibiotics, pain medications, and warm compresses, especially if they have already ruptured. Other anal sac abscesses may need to be surgically managed in order to open, drain, and flush the area.
The most common anal sac tumor is called anal sac adenocarcinoma. This is treated with surgery and often with adjunct chemotherapy and/or radiation, depending on extent and stage of disease.
Frequency of clinical signs or recurrence of anal sac disease can help determine if further workup is needed. If there is a recurrent issue, screening lab work for any underlying metabolic or endocrine disorders is often submitted. Consideration is also given to allergies, as they can predispose dogs to recurrent anal sacs infection and inflammation. Food allergies are evaluated with a hypoallergenic or novel protein diet. If there are signs of more diffuse allergic skin disease, more complete allergy testing can be considered. Supplements such as Glandex have been helpful for some dogs. Others have a good response to a high fiber diet. In some severe cases of chronic anal sac disease that cannot be medically managed, anal sac excision is an option that can be discussed.
So if your dog is scooting, licking, chewing, or seems uncomfortable in their back end area, start with an evaluation with your veterinarian. Not every case responds to the same treatment plan, but we will discuss our findings and recommendations to help your pup feel their best!
