"Doctor, help! My dog has worms." "Oh, what makes you say that?" "Because he keeps sliding around on his rear end." So many times I have heard a worried client make this statement. Actually the vast majority of the time, these "bob sledders" are experiencing problems with their anal sacs. But what are anal sacs?

Dogs and cats, as well as a few other domesticated pets, possess two small sacs which are located on either side of the rectum at about 3 o'clock and at 9 o'clock. The sacs are about the size of a small grape on an average thirty-pound dog. They have a small opening or duct, which opens just at the exit of the rectum. Just beneath the skin, around the sacs are little anal glands, which secrete fluid into the anal sacs. This fluid has a sharp, pungent odor. The anal sacs are equivalent to the skunk's scent glands. Thousands of years ago the dog's ancestors probably used the glands, as do skunks, to spray enemies or to mark territory. However, over the years, through evolution, these structures became smaller and less specialized to the point of not really being used anymore, comparable to the human appendix.

Most animals go through life and never have any problems with their sacs. However, some dogs (especially miniatures and toys) do have problems. The anal sacs are normally expressed regularly when your pet exercises vigorously or moves its bowels. Sometimes the small openings or ducts get plugged or dried up and cannot be emptied normally. Your pet will lick or chew at the anal area or will be seen "bob sledding" along on its rear end with the back legs straight out in front. Usually your pet will be able to express the sacs in this secondary manner. If the secretion in the anal sac is not emptied, impaction and infection will occur.

If one or both of the anal glands are simply impacted, you may want to try to treat it yourself at home. Cover the anal area with a tissue or paper towel. Place your thumb and your finger at the 3 o'clock and 9 o'clock positions outside the anal area. Squeeze firmly in towards the center and a little bit backwards. The anal sac contents should exit from the duct of the anus. You will know you have done it correctly because you will smell the secretion. (See Figure 1). If you are unsuccessful and your pet still seems uncomfortable, go see your veterinarian.

Sometimes owners may not notice the early warning signs and the anal sac impaction proceeds to become an anal sac infection or abscess. If this occurs in one or both of the sacs, the area adjacent to the anus will become red, swollen and painful. If and when the abscess ruptures, pus or a blood-tinged fluid may drain from the opening.

Obviously, this situation calls for an immediate visit to your veterinarian. The veterinarian will most likely flush and fill the anal sacs with sterile water and antibiotics as well as dispense oral medication until the infected tissue heals. Often this treatment will require sedation or anesthesia as the rectal area is quite painful.

Owners can help prevent these problems in their pets. If your pet is prone to impactions, then frequent expressing of the sacs by you or your veterinarian can decrease the chances of anal impactions or infections from developing. If your pet has repeated bouts of infection, then the anal sacs can be removed surgically.

Although anal sac impaction is the most common anal sac problem, there are a few other "anal problems" that a conscientious pet owner should watch for.

Anorectal Polyps are benign growths of the rectal lining that may or may not be seen to poke out of your pet's rectum. These growths do not spread but can cause local discomfort, straining, or blood tinged formed stool. Surgical removal is the best treatment and is usually curative.

Perianal Gland Tumors are usually benign growths (adenomas) that come from modified sebaceous glands of the skin in the rectal area. They do not come from the anal glands but may occur in the same area or even on the underside of the tail. Multiple tumors may be present. Although they are benign, they often have raw bleeding surfaces that will not heal. These tumors are primarily found in males and are thought to be hormonally stimulated. Rarely a malignant form called a Perianal Gland Adenocarcinoma will form. Finally, an Anal Sac Carcinoma is a malignant tumor derived from the anal glands of the anal sac itself.

Therapy differs depending on the extent of the tumor. Perianal Gland Adenomas usually respond well to surgical excision. At the same time it is advisable to neuter the male dog to remove the hormonal stimulation and decrease or limit recurrence. Incompletely removed masses often respond well to the castration. If not, they can often be treated with radiation therapy. Perianal Gland Adenocarcinomas and Anal sac Carcinomas both invade tissues locally and spread by the blood stream and lymphatic to distant sites elsewhere in the body. If these conditions are caught early enough before metastasis, then surgical excision followed by radiation therapy offers a possible treatment. However, the long-term prognosis is poor. Each case is a little bit different and your veterinarian is the best person to advise you as to what the treatment is best for your pet.

Overall, it is important to remember that your pet scooting its bottom over the floor could be a signal of an anal sac problem, it could be a possibility that it is caused by worms. Worms account for about 10-15% of those "bob sledders." Most of these cases are due to tapeworms. The tapeworm is the only worm you will actually see with the naked eye. Tapeworms can pass out of your pet's rectum and cause itching of the anal area. Should this be the cause of the problem, your veterinarian can prescribe an anthelminitic for your pet to rid it of the tapeworm. After that a good flea control program can prevent future tapeworm infection. Either way, it is important to observe your pet's behavior and follow up with your veterinarian when you notice any change of abnormalities. It's the best thing you can do for your pet.

-Dr. Michael Shaff owns and practices The Animal Clinic of Woodmont at 8295 N. Pine Island Rd in Tamarac, FL. A university of Pennsylvania graduate, he is also a member of the South Floria Acaamy of Veterinary Medicine. He can be reached at (954) 726-3647.