Anal sacs (also referred to as anal glands) are a pair of glands just under the skin adjacent to a pet's anus. The anal sacs fill with a foul-smelling fluid that's normally expressed through tiny ducts during defecation. Though dogs and cats have historically used their anal gland secretions to mark their territory, our pets often express these glands when they're anxious or frightened.
Anal sacculitis is a term reserved for the frustrating condition characterized by the inflammation of these anal glands. Pets so affected experience a build-up of fluid in their anal sac, an uncomfortable condition that can lead to pain and itching. Should this condition progress, the anal sacs can become infected or abscessed (filled with pus), usually only on one side.
Anal sacculitis has been correlated with allergic skin disease, perianal fistulas, and gastrointestinal disease (especially with the production of poorly formed stool). Anecdotally, it is also correlated with obesity in cats. But, mostly, anal sacculitis is considered idiopathic, which is to say we don't properly understand its cause.
Dogs and cats of any age may be affected, but dogs are far more likely to suffer from anal sacculitis than cats.
Symptoms and Identification
Affected pets typically display one or more of the following symptoms:
Frequent licking or "chasing" of the area
Rubbing or "scooting" the backside on the ground
Leaking foul-smelling fluid (usually onto bedding)
Straining or pain upon defecation
Some pets, however, display no symptoms whatsoever. They may be identified as possibly suffering from anal sacculitis only if their glands are routinely expressed.
If the condition progresses in asymptomatic cases, infection of the glands is possible. If an abscess results from the infection, the affected side typically becomes swollen and red and will almost always open to exude a bloody pus.
Anal sacculitis is typically identified by correlating symptoms with visual inspection and palpation upon expression of the anal glands. Confirmation of a lesion as an anal gland abscess is similarly undertaken by visual inspection but a biopsy of the affected area may be deemed necessary if a cancerous tumor is suspected as the underlying cause.
There is no confirmed breed predisposition in either cats or dogs, but smaller breeds of dogs and overweight cats appear to be overrepresented.
Initial treatment usually involves the manual expression of the anal sacs. The frequency of this procedure depends on the patient's individual degree of discomfort but can range from every week or two to every few months.
Increasing dietary fiber is also commonly recommended, as is the infusion of a combination of antibiotic and corticosteroid medications directly into the affected anal sacs. Use of oral corticosteroids and antibiotics may also be indicated, though systemic antibiotic treatment is considered questionably effective.
Abscessed glands typically require surgery.
For difficult cases in which anal glands offer chronic discomfort or recurrent abscesses, a surgical procedure to remove them (called anal sacculectomy) is sometimes considered the best option.
The cost of veterinary care is relatively low for dogs and cats whose anal glands never become infected or abscessed. Their expenses are typically relegated to frequent expression alone -- usually under $50.
The cost of infected or abscessed glands, however, is significantly higher since infected glands require frequent in-hospital drug infusions and abscessed glands typically require a surgical procedure, albeit a simple one. Owners can expect costs to vary from $100 to $1,000 per uncomplicated incident.
Should anal sacculectomy become necessary, expected costs will be much higher. That's because this potentially complication-fraught procedure is often best performed by a veterinary surgeon whose prices are commensurate with his or her high degree of skill. Depending on geographic locale, this usually ranges anywhere from $750 to $2,500.
There is no known method for the prevention of idiopathic anal sacculitis in dogs. However, frequent manual expression and treatment of any underlying medical conditions, such as allergic skin disease, perianal fistulas, and gastrointestinal disease can be very effective in preventing the recurrence of anal sacculitis in these patients.
Keeping cats lean is probably somewhat effective in preventing anal sacculitis in cats predisposed to it.
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James DJ, Griffin CE, Polissar NL, Neradilek MB. Comparison of anal sac cytological findings and behaviour in clinically normal dogs and those affected with anal sac disease. Vet Dermatol 2011;22(1):80-87.
Pappalardo E, Martino PA, Noli C. Macroscopic, cytological and bacteriological evaluation of anal sac content in normal dogs and in dogs with selected dermatological diseases. Vet Dermatol 2002;13(6):315-322.
Robson DC, Burton GG, Lorimer MF. Cytological examination and physical characteristics of the anal sacs in 17 clinically normal dogs. Aust Vet J 2003;81(1-2):36-41.