Affections of Anal Gland and Their Surgical Management

Anal glands

Anal glands or anal sacs are small glands located beneath the skin on either side of anus between external and internal sphincter muscle at about the four and eight o'clock positions. In dogs, these glands are occasionally referred to as "scent glands", because they enable the animals to mark their territory and identify other dogs. They are connected with the anus by means of small canals or ducts. The secretion that comes from these glands is brown in color and about the consistency of water or oil. The secretion has a very disagreeable odor to humans. As the pet defecates, the anal sphincter squeezes the sacs against the hard passing feces and causes the anal secretion to discharge onto the fecal mass, lubricating the anal opening. The sacs are also emptied when the dogs are frightened or scared. The external anal sphincter is innervated solely by the caudal rectal nerves.

Fig: Illustration demonstrating the relationship between the anal sacs and ducts and the internal and external anal sphincter muscles.

Affections of anal glands

Nowadays the pet dogs are kept in an enemy free environment, so anal sacs are rarely emptied. Similarly, if dogs ate large quantities of meat and bone making their feces hard in consistency anal sac emptying becomes easier but feeding of vegetable proteins produces a much softer stool so there is nothing for the glands to be squeezed against. Under such conditions the fluids build up and solidify thus presenting an ideal environment for bacterial growth.

Disorders that occur in the anal sacs are impaction, infection, abscessation and neoplasia. Anal sacculitis is common affecting approximately 10% of dogs, and usually is caused by infection or duct obstruction, and inflammation. Inflammation enhances secretion which serves as an ideal medium for bacterial growth. Secretions continue to accumulate despite ductal obstruction, and the sacs become impacted and eventually rupture. Chronic fistulation may result if infection or duct obstruction persists. Anal sacculitis also occurs without duct obstruction. In these cases hypersecretion occurs and the sac is

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easy to express. Secretions are more liquid than normal with yellowish white granules. Factors that may cause chronic hypersecretion include infectious, endocrine, allergic, behavioral, and idiopathic mechanisms. Malfunction of the anal sphincter mechanism secondary to chronic diarrhea, anal laxity, constipation and obesity may contribute to retention of anal sac secretions and the development of anal sacculitis.

Anal sac tumors arise from the glands of the anal sac, and may be benign (anal sac adenomas) or malignant (anal sac adenocarcinomas)—most anal sac tumors are of the malignant type. These anal sac adenocarcinomas make up approximately 2% of all skin tumors seen in dogs, and of these dogs, the majority are older females. There are no obvious breed predilections and this type of tumor occurs in both intact and neutered animals. Anal sac adenocarcinoma is very rare in cats, but has been reported.

The tumor itself is usually unilateral (affecting only one of the anal sacs), however bilateral tumors have been recognized, so both anal sacs should be carefully examined. The mass may be discrete or infiltrative, and can be very small (less than 1 cm in diameter) or quite large (up to 10 cm or more in diameter). It frequently produces a hormone which causes blood calcium levels to rise above normal levels. This is known as hypercalcemia of malignancy, and can cause problems with other organs such as the kidneys. In addition, anal sac adenocarcinomas have often metastasized (spread) by the time they are initially diagnosed. They may spread first to regional lymph nodes, such as the sublumbar lymph nodes, and later to the lumbar spine or more distant sites such as the liver, spleen, or lung

Many dogs have recurrent anal sac disease. It may occur in an animal of any age, breed or gender however, it is most common in small and toy breed dogs and rare in cats. Some breeds of dogs, like Poodles, commonly have problems. In some animals anal sacculitis may be associated with seborrhoic dermatitis or other dermatoses.

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Fig: Anal Sac tumor fig: anal sac abscess

Diagnosis

Physical examination: Routine palpation and expression of the anal sacs during physical examination may allow early detection of anal sac disease. Impaction is diagnosed when the sac is distended and mildly painful and cannot be readily expressed. Anal sacculitis is diagnosed when moderate or severe pain is elicited on palpation, and secretions are liquid, yellowish, blood tinged or purulent. The diagnosis of anal sac abscessation is made when there is marked distention of the sac with a purulent exudates, cellulitis of surrounding tissues, erythema of overlying skin, pain and fever. An anal sac rupture is diagnosed by finding a draining tract associated with the anal sac.

Radiography and ultrasonography: Plain radiograph are recommended if neoplasia is suspected. A fistulogram may help determine whether a draining tract is associated with the anal sac region or some other perineal location.

Laboratory findings: Hematologic and serum biochemistry changes are nonspecific. Leukocytosis with a left shift may be noted with anal sac abscesses. Cytological studies from diseased anal sac secretions reveal cellular debris, large numbers of leukocytes, and numerous bacteria. Culture and sensitivity testing of the anal sac is recommended. The normal bacterial flora of anal sac include small numbers of micrococci, Escherichia coli, Streptococcus faecalis, and Staphylococcus spp. Bacteria typically cultured from diseased anal sacs include S. faecalis, Clostridu\ium perfringens, E. coli, Proteus spp., Staphylococcus spp., micrococci and diphtheroids. Blood calcium level is increased in anal sac tumor.

Differential diagnosis: The primary differential diagnoses for anal sacculitis are flea allergy ( from licking and biting), perianal tumor ( caused by swelling and ulceration), perianal fistulae or tail fold pyoderma ( resulting in absceasation and draining tracts). Differential diagnoses for anal or perianal irritation includes anal sacculitis, dermatitis, endoparasites, perianal fistulae, vaginitis or tumors. Differential diagnoses for perrianal swelling include perianal hernia, perianal neoplasia, perianal gland hyperplasia, anal saccuulitis,

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Symptoms

1. Scooting or dragging the anal area2. Excessive licking and biting of the anal area3. Pain, sometimes severe, near the tail or anus4. A swollen area on either side of the anus5. Bloody or sticky drainage on either side of the anus6. Tail chasing behavior and other behavioral changes7. Tenesmus, dyschezia, constipation and hematochezia occasionally occur.8. Generalized dermatitis or dermatitis at a secondary site sometimes are recognized.9. Febrile and debiliated animal10. Digital expression of anal sac expels normal secretions ( serous, slightly viscid, granular, pale

yellow liquid) or abnormal secretions ( whitish gray, brown, yellow or green, bloody, purulent, gritty, turbid, opaque ).

anal sac neoplasia , antresia ani, rectal pytiosis, and vaginal tumors differential diagnoses for dyschezia include rectal foreign body, perineal hernia, perianal fistulae, anal stricture, rectal stricture, anal sac abscess, rectal neoplasia, anal neoplasia, anal trauma and dermatitis, rectal pythiosis and and rectal prolapse.

Medical treatment

Treatment depends on the stage of infection. Most anal sac problems can be medically managed by manual expression, lavage, antibiotics and dietary change. Treatment of concomitant dermatoses facilitates treatment of anal sacculitis. Mild sacculitis or impaction is treated by expressing, lavaging with saline), and infusing the glands with an antibiotic- corticosteroid preparations. Dry secretions may be softened by lavaging with saline or infusing a ceruminolytic agent. If the anal sacs are infected. 0.5% chlorhexidine or 10% povidone iodine may be added to saline flushes. Adding fiber to the diet makes the feces bulky, which may stretch the anus during defecation, causing the anal sacs to be compressed and emptied,. In more severe cases, weekly evaluation, expression, and lavage with a dilute antiseptic solution or saline may be required. Oral antibiotics in chronic cases are chosen based on sensitivity results. Anal sac abscesses should be lance, drained, and flushed. Hot compresses, applied two or three times daily for 15 to 20 minutes each, are beneficial for abscesses. Appropriate oral antibiotics should be administered to patients with anal sac abscesses. Chemical cauterization is not recommended, because severe perineal sloughing may result.

Surgical treatment (anal sacculectomy)

Failure of medical therapy and suspicion of neoplasia are indications for anal sacculectomy. If a draining tract persists after anal sac rupture, surgery should be delayed until inflammation is controlled. Both anal sacs should be removed, even if only one is obviously involved.

Preoperative management: Anal sacculitis, abscessation or fistulation should be treated for several days as described above to reduce inflammation before surgery. Inflammation and fibrosis present at the time of surgery increase the risk of damage to the anal sphincter. Temporary or permanent fecal incontinence may result secondary to sphincter damage.

Anesthesia: For dogs premedication is done with atropine @ 0.02-0.04mg/kg IM,IV or SC or glycopyrrolate @0.005-0.011 mg/kg IV,IM,SC plus butorphenol @0.2-0.4mg/kg SC or IM or oxymorphone 0.05-0.1mg/kg DC or IM. Induction is done with thiopental @10-12mg/kg o propofol @4-6mg/kg administered IV to effect. Maintenance is done by isoflurane or halothane.

In cats premedication done with atropine @ 0.02-0.04mg/kg IM,IV or SC or glycopyrrolate @0.005-0.011 mg/kg IV,IM,SC plus ketamine @5mg/kg IM plus butorphenol @0.2-0.4mg/kg SC or IM. Induction is done with diazepam @0.2mg/kg plus ketamine 5.5mg/kg combined and administered IV to effect or thiopental 10-12 mg/kg or propofol 4-6mg/kg administered IV to effect and maintenance is done by isoflurane or halothane.

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Surgical anatomy: At the junction of the rectum and anus, the mucous membrane contains the anal glands. A small opening on either side leads to two lateral anal sacs. These anal sacs contain a dirty grey fatty substance which has very unpleasant odor. The anal sac orifice is located at the anal orifice at approximately 4 and 8 o’clock position. The skin which lines anal sacs contains oil glands.

Positioning: Regardless of the technique used, the animal is positioned in sternal recumbency with its hindlimbs hanging over the edge of a well-padded table. The tail is reflected over the dorsum of the dog and secured using 2-inch medical tape. A purse-string suture is placed to close the anal orifice, leaving the duct openings outside the suture.The perianal area is then surgically prepped.

Surgical technique

There are several different methods for anal sacculectomy, but surgical approaches can be simply categorized as open or closed techniques. Some surgeons prefer an open approach because of its speed and simplicity and because the lining of the anal sac is visualized to ensure complete removal. However, more extensive contamination of the surrounding tissue occurs than with use of a closed technique, which may increase the potential for postoperative incisional infection. Closed techniques are indicated in animals undergoing anal sacculectomy for tumor excision; however, some surgeons also prefer closed methods for cases of anal sacculitis due to the decrease in surgical site contamination. Regardless of the technique used, the potential for hemorrhage exists, particularly with aggressive dissection. Hemorrhage can be controlled with digital pressure or electrocautery. Blind grasping for bleeding tissue using hemostats or forceps can result in damage to the caudal rectal nerve and should be avoided. Both open and closed techniques for anal sacculectomy can be performed using a carbon dioxide laser. The proposed advantages of this modality include decreased bleeding, reduced pain, less swelling, and decreased rate of infection relative to standard techniques. Perioperative antimicrobial use is advocated because anal sacculectomy is considered a contaminated procedure based on the location of the surgical site.

Open method

Open techniques involve direct incision of the anal sac to expose the secretory lining. Using a scalpel blade, incise from the duct orifice down the entire length of the gland. Alternatively, pass one blade of sharp Metzenbaum scissors into the duct and anal sac. Elevate the tissue toward the surface while closing the scissors, thereby incising the gland and the overlying external anal sphincter muscle fibers, subcutaneous tissue, and skin. The open technique can also be accomplished by placing a grooved director through the duct into the most ventral part of the sac. Bring the tip toward the skin surface and make an incision over the director with a scalpel blade, spanning the entire length of the duct and sac. Regardless of how the open incision is performed, grasp the anal sac with forceps and retract it through the incision. The sac can be distinguished from the surrounding tissue by the uniquely gray color of the epithelial lining, which may also have a shiny appearance. Using sharp and blunt dissection, completely remove the anal sac from the surrounding external anal sphincter. Take care to stay as close as possible to the anal sac to avoid additional damage to the sphincter muscle. A modified open technique that requires only partial opening of the sac has also been described. This technique allows for a smaller incision and less trauma to the external

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anal sphincter than a traditional open technique. To perform this procedure, incise the duct orifice and continue the incision only until the lining of the sac is identified. Clamp hemostats on the incised tissue and continue dissection from the sac orifice in a ventrolateral direction toward the base of the sac. Keep dissection as close as possible to the anal sac to avoid damaging surrounding tissue without perforating the anal sac.

Closed method

Closed techniques attempt to keep the anal sac completely intact, and dissection is directed from the base of the gland toward the duct. Make a vertical incision lateral to the anal orifice over the base of the sac. Use careful sharp and blunt dissection to free the anal sac from the muscular fibers of the external anal sphincter. The most difficult part of the procedure can be dissecting the anal sac away from the surrounding tissue. Tools that can help with this aspect of the surgery include delicate, curved Metzenbaum scissors, which can be used to follow the angles of the sac; a scalpel blade held at a flat angle, used to peel the muscle fibers away from the sac; and low-voltage electrocautery, used to strip away the surrounding tissue. Continue dissection from the base of the gland toward the duct. Ligate the duct with a small (4-0) monofilament absorbable suture before transection. Several materials have been used to fill the sac to allow easier resection like Suture material, Umbilical tape, String or thread, Anal sac gel, Self-hardening resin, Dental acrylic, Plaster of paris, Melted paraffin, Curved hemostat, Grooved director, Foley catheter etc. however, some heated or self-hardening materials could cause dermal or subcutaneous inflammation. Foley catheter is inflated with 3 mL of saline. The distal part of the catheter beyond the balloon can be cut off to allow easier placement, particularly in smaller patients. The balloon is deflated, the catheter is inserted into

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Open technique

A, a groove director is placed into the anal sac duct to the most ventral aspect of the sac lumen . B, an incision is made over the groove director to expose the anal sac lining. C, the anal sacc and its duct are dissected from surrounding tissue and removed. D, routine closure

the anal sac, and the balloon is reinflated. An incision is made over the base of the sac, which is now easily palpated. The sac is easily dissected from the tissue, and the balloon allows the sac to be removed with minimal disruption of the external anal sphincter. The size of the patient can be a limitation to the use of this technique because even the smallest Foley catheter may be too large for small dogs and cats.

Closure

Regardless of the technique used, the area should be thoroughly lavaged and closed routinely. In an open technique, the fibers of the external anal sphincter are reapposed with 3-0 or 4-0 monofilament absorbable suture using a simple interrupted pattern. Subcutaneous tissues are closed in a simple interrupted or simple continuous pattern using 3-0 or 4-0 monofilament absorbable suture. The skin is closed with simple interrupted or cruciate sutures using 3-0 monofilament nonabsorbable suture.

POSTOPERATIVE CARE

Postoperatively, dogs should be prevented from licking the surgical site through use of an Elizabethan collar. Stool softeners can be administered, although they are not usually necessary. Postoperative pain can typically be managed with oral analgesics. Opioids and opioid-like substances may cause constipation; therefore, NSAIDs may be preferred if there are no contraindications to their use. Antibiotics are often continued until suture removal because of the high level of contamination at the surgical site.The incision should be monitored closely for signs of infection until the sutures are removed 10 to 14 days after the surgery.

COMPLICATIONS

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Closed technique

A, insert a hemostat into the anal sac.B. make an incision at the lateral aspect of the anal sac and carefully dissect the sac from the sphincter muscle fibers. C, ligate the duct near the orifice

Complications associated with anal sacculectomy include postoperative straining, incisional infection, fistula formation, anal stricture, and fecal incontinence. Fecal incontinence occurs if there is significant damage to the external anal sphincter or caudal rectal nerve. Damage is typically caused by aggressive dissection when removing the sac. If only one caudal rectal nerve is injured or if less than 50% of the external anal sphincter muscle is traumatized, fecal continence is usually retained. Transient fecal incontinence lasting from several days to 2 weeks may occasionally occur due to mild injury to the external anal sphincter muscle, neuropraxia resulting from surgical inflammation, or the animal’s initial discomfort associated with voiding. A fistula can form when any part of the epithelial lining of the anal sac is left behind. This complication also seems to be more likely when an open technique is used. Surgical exploration and resection of any residual tissue are required to resolve this complication. This is often a more technical surgery because the area must be delicately explored for all epithelial tissue, and the risk for nerve damage and hemorrhage is greater. The overall rate of complications for anal sacculectomy is very low; therefore, the prognosis for nonneoplastic anal sac disease following anal sacculectomy is good to excellent.

Bibliography:

1. Archibald,J. (Ed.). 1974. Canine Surgery. Second edition. American Veterinary Publications, USA.

2. Bojrab, M.J. (Ed).1983. Current Techniques in Small Animal Surgery. Second edition. LEA and FEBIGER publishing, Philadelphia.

3. Degner D. A.2004. Anal Gland Cancer. Vet Surgery Central Inc. http://www.vetsurgerycentral.com/anal_sac.htm. Retrieved on 2011-4-27

4. Dr. Dan. 1999. Anal Sac Disease–Scooting. The Petstuff Online Newsletter http://www.petinfoforum.com. Retrieved on 2011-4-27.

5. Fossum, T.W. Small Animal Surgery. Mosby Publications, USA6. Kafle, D .2005. Anal Sac Diseases in Dogs in: The Blue Cross Volume 7.7. MacPhail C. 2008. Anal Sacculectomy. Surgical View, Colorado State University.

http://www.hungarovet.com/wp-content/uploads/2009/04/anal-sacculectomy-surgery-compendium.pdf . Retrieved on 2011-4-27.

8. Slatter, D.S.1993. Textbook of Small Animal Surgery. Second edition, vol. 1. W.B. Saunders Company.

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