Salivary Mucocele

By: April Guille, DVM, Diplomate ACVS

A salivary mucocele, or a sialocele, is a collection of saliva in the subcutaneous tissues near the site of a leaking salivary duct or gland. The most common gland affected is the sublingual salivary gland, but any of the four major salivary glands can cause a sialocele. The location of the swelling often determines the presenting signs and indicates the involved salivary gland. The two most common locations of saliva collection are the ventral cervical area and under the tongue, although swelling can occur in the pharyngeal area, causing dyspnea, or under the ventral orbit, leading to exophthalmos. Animals with labored breathing due to a pharyngeal sialocele are in danger of airway obstruction and the swelling should be opened up for immediate drainage. Sialoceles can be caused by trauma, sialoliths, neoplasia, foreign bodies, or recent oral surgery, but often the cause is unknown. No sex predisposition has been found; dachshunds, poodles, Australian silky terriers, and German shepherds are predisposed.

On aspirate, the fluid is often viscous and clear or blood-tinged with small to moderate numbers of nondegenerate nucleated cells in a proteinanceous background. Conservative treatment by drainage alone is not recommended due to the high rate of recurrence. Definitive treatment involves removing the affected glands along with drainage; ranulas and pharyngeal sialoceles are treated with marsupialization. Although the sublingual gland and duct system are the most commonly affected, removal of the sublingual gland requires removal of the mandibular gland as well due to their common capsule and close association. The prognosis is excellent with complete removal of the gland, with a recurrence rate of less than 5 percent.

Facts about Sialoceles

Four main presentations include exophthalmos, labored breathing, dysphagia, or ventral cervical swelling

Sublingual salivary gland is the most commonly affected gland

Surgical removal of the affected gland is recommended to prevent recurrence

Excellent prognosis with surgery


Surgical Introduction

  Our state of-the-art surgery suite is equipped with modern anesthesia machines, heated surgery tables, and patient monitoring devices. Our surgeons specialize in soft tissue and orthopedic surgeries. Many Maine veterinarians refer more complicated procedures to our surgeons.
Many pet owners are unaware of specialization in veterinary medicine although they are quite familiar with it in human medicine. A specialist in veterinary medicine is quite similar to the human counterpart, both having gone through additional years of study and training to dedicate themselves to their chosen area. As the human physician will refer patients to a surgeon for complicated procedures, veterinary practitioners often refer surgical cases to a veterinary surgeon.

The American College of Veterinary Surgeons (ACVS) was formed to acknowledge and regulate the training and certification of veterinary surgeons. To achieve Diplomate status in the ACVS, a veterinarian must complete at least four years (one year of internship and three of a surgical residency) in a program accredited by the ACVS. Upon completion of the residency the candidate must submit credentials to the ACVS for review. The credentials document the individual’s training including all the surgeries they have performed, the Diplomate who supervised them, all class work done, lectures given, and scientific papers published. If these credentials are accepted, they are invited to sit for the certifying exam. This is a two day exam consisting of oral, written, and practical portions. Only upon successful completion of all three parts do they attain the status of Diplomate in the American College of Veterinary Surgeons. This is a rigorous and time consuming process that ensures that those achieving Diplomate status are fully qualified to perform any and all types of specialized surgery that your pet may require. Small animal surgery is typically divided into three areas: orthopedics, soft tissue, and neurosurgery.

Orthopedic surgery involves bones, joints, muscles, tendons, and ligaments. Fractured bones and torn ligaments are some of the most common injuries seen by the veterinary surgeon. In many cases, there are multiple injuries to the pet often as the result of trauma. Advanced techniques including the use of steel plates and screws or elaborate bone pin and clamp systems are required to adequately stabilize these injuries so that the pet can heal normally.

The surgeon also sees more subtle, chronic injuries that can be difficult to diagnose and frustrating to the pet owner. Sporting dogs, like human athletes, may acquire these injuries that though not debilitating, decrease their performance in the sport. Often, however, these sporting dogs are stoic and do not show their pain easily. A thorough orthopedic exam, radiographs (x-rays), and specialized procedures may be required to make the diagnosis in these complex cases.

Hip Dysplasia
Of course not all orthopedic problems are the result of injury. Many pets are born with conditions that eventually cause debilitating lameness. Hip dysplasia is a condition where the hip joint is malformed resulting in a looseness or laxity. This laxity leads to the development of arthritis. Hip dysplasia is a well recognized condition that is widespread in many breeds today. It can be heritable or passed on from generation to generation, but heredity is only part of the problem. Two parents with normal hips can produce a dysplastic puppy though the chance is less than if one or both parents has hip dysplasia. Do not ignore the signs of hip dysplasia just because you were assured that your puppy would not have it. The signs of hip dysplasia can include "a bunny hopping" gait (both rear legs move forward together), an obvious lameness, trouble getting up, and/or hesitancy to jump or go up and down stairs. The diagnosis of hip dysplasia is made with an orthopedic exam and radiographs (x-rays) of the hips. Young dogs should be examined by a veterinarian early as there are treatment options to prevent debilitating arthritis. (see advanced techniques)

Osteochondritis Dissecans (OCD)

Osteochondritis dissecans (OCD) is another congenital abnormality which can occur in any joint although it is most commonly seen in the shoulder, elbow, stifle (knee), and hock (ankle). Technically it is a failure of subchondral ossification which in general terms means the cartilage of the joint is not well attached and results in a loose flap of cartilage in the joint. It can cause significant lameness and arthritis. The treatment of choice is usually surgical removal of the loose piece via arthrotomy (opening the joint) and arthroscopy. The outcome depends on the joint or joints involved and the degree of arthritis already present. The diagnosis is made with radiographs (x-rays) and again early diagnosis is beneficial.

The elbow joint has several conditions besides OCD which can occur in the young dog. These include fragmented coronoid process (FCP), ununited anconeal process (UAP), and malalignment of the joint surface. The first two, FCP and UAP, are similar to OCD in that there is a loose fragment (in these cases bone as well as cartilage) that causes lameness. The third condition, malalignment, is where the joint surfaces of the three bones that meet at the elbow (the humerus, the radius, and the ulna) do not fit together. This may be because either the radius or the ulna is growing too fast for the other bone to "catch up". All of these conditions can result in debilitating arthritis. They are diagnosed by radiographs and surgery can be performed to correct the problem or alleviate the pain if diagnosed early in the disease process.

Other growth deformities are seen in pets as a result of birth defects or trauma to the young animal. Corrective surgery should be performed to give the pet normal or near normal use of the limb.

Soft tissue surgery is a very broad category involving head and neck surgery, cardiovascular (heart), pulmonary (lung), gastrointestinal (stomach, intestine, liver, pancreas), and urogenital (kidneys and bladder). The conditions in each category may be either congenital (from birth) or acquired. Acquired disorders are those not related to hereditary or birth defects, and include trauma, infection and cancer.

Patent Ductus Arterious (PDA)
Some diseases cats and dogs are born with that require surgery include heart and blood vessel problems such as patent ductus arteriosus (PDA) and persistent right aortic arch (PRAA). A PDA is a blood vessel that is present in the fetus that should close down at or shortly after birth. If it stays open, blood is shunted from one side of the heart to the other overloading the system. The puppy or kitten will have a heart murmur that can be detected on physical exam. They often act quieter that normal and tire easily. The diagnosis is made by detecting the murmur, radiographs of the chest, and/or ultrasound exam of the heart. Surgery can completely correct this condition. A thoracotomy (incision into the chest cavity) is performed and the abnormal vessel is closed off with suture material.

Persistent Right Aortic Arch
A persistent right aortic arch (PRAA) is the abnormal development of blood vessels which results in a tight band constricting the esophagus. The esophagus is the tube which brings food from the mouth to the stomach. When the puppy or kitten starts eating solid food, they will be unable to hold it down for much of the time. The diagnosis is made by introducing special dye into the esophagus and taking radiographs (x-rays). To correct this, a thoracotomy is performed and the tight band of tissue is removed, alleviating the obstruction. It is important to do this surgery as early as possible to prevent permanent damage to the esophagus.

Ectopic Ureters
Another congenital defect involves the urinary system and is called ectopic ureters. The ureter is a tube that brings urine from the kidney to the bladder. In the ectopic ureter condition this tube does not empty into the bladder but instead goes further out to the urethra or vagina. Pets with this condition are often incontinent (leak urine), have urine scald around their genitalia, and develop urinary tract infections. This condition is also diagnosed with a special dye that identifies the abnormal ureter. Abdominal surgery is performed and the abnormal ureter is attached to its normal position in the bladder. Once again, early diagnosis is beneficial.

Surgery on pediatric animals requires specialized equipment, supplies, and expertise. Heated surgery tables help patients maintain body temperature, certain intravenous fluids are given to stabilize blood sugar, anesthetic drugs are carefully selected, and careful and complete monitoring of anesthesia are performed to ensure a complete and speedy anesthetic and surgical recovery. Once the young patient is awake from surgery recovery is remarkable. Even chest surgery patients are eating within one hour and dozing comfortably. They are often running and playing within a week of surgery and would be even sooner if they were allowed!



Acquired soft tissue diseases or conditions are many and varied. Pets may ingest inanimate objects that require surgery to remove or they may suffer trauma requiring surgery such as a ruptured spleen or bladder from being hit by a car. Pets can get diseases like humans such as gallstones, kidney or bladder stones, and stomach ulcers. Like their human owners with these conditions, surgery is sometimes necessary.

A large part of soft tissue surgery is now oncological (cancer) surgery. Cancer can and does occur in any part of the body and can be either benign or malignant. The best test to determine the type and nature (benign or malignant) of a tumor is a biopsy where a portion or all of the tumor is removed and sent to a pathologist for microscopic classification.

Benign tumors may need to be removed if they are interfering with the other neighboring body structures, enlarging dramatically, causing discomfort, or are unsightly. If completely removed, the benign tumor should not recur or spread to other body areas. One example of a benign tumor is a lipoma or fatty tumor that occurs anywhere, but is often seen and felt under the skin in older pets. A simple aspirate using a small needle to obtain a sample is usually adequate for diagnosis. Surgical removal results in a skin incision that heals rapidly and causes minimal discomfort for the pet.

Malignant tumors often require a more aggressive approach and additional therapy beyond surgery, including chemotherapy or radiation. Surgery, however, is the main stay of many cancer therapies and is often the only hope for a complete cure.

Malignant tumors can be deceivingly small in appearance and what can be seen may only be the "tip of the iceberg". It is therefore very important to be aggressive with surgery making a wide surgical excision in an attempt to get rid of all of the cancer. This may involve removing a portion of the chest wall and ribs in cases of tumors of the thorax (chest); removing half of the lower or upper jaw in the case of oral (mouth) tumors; or amputating the limb in cases of bony tumors of the limb. These may sound drastic but are often essential for cure. The biggest mistake in oncological surgery is to perform inadequate resection allowing the cancer to recur. It may be more difficult or impossible to completely remove at a second surgery, the cancer may have spread to other areas in that time interval, and it means a second surgery for the pet. The first chance is the best chance for cure. Even aggressive (radical) surgery in most pets is very well tolerated and can be very cosmetic. Early intervention is the key to success!


Pain Management
Whenever surgery is performed, there is some postoperative pain. The amount and duration varies with the type of surgery and the condition of the patient. Although we cannot ask the pets how they feel, we can and should assume it is similar to humans. A spay is probably less painful than amputation but both surgeries require addressing pain management (analgesia).


Pain control starts before surgery is performed. We now know that medicating prior to the onset of pain results in better pain control with less total drug required. This is called pre-emptive analgesia. All of our surgical patients receive a premedication drug, the type and amount depending on the level of expected discomfort. After surgery additional pain medication is often required. This may be injectable and given intermittently or on a slow intravenous dose. Oral medications for pain is often prescribed for the first few days to weeks at home.

An important part of patient comfort is TLC postoperatively. Providing warmed blankets and heating pads, a clean and dry bed, and a good scratch behind the ears, go a long way toward lessening their discomfort and anxiety.

Triple Pelvic Osteotomy (TPO)
Hip dysplasia is a condition where the femoral head and acetabulum (the ball and cup) of the hip joint do not fit well together. The cup or acetabulum is too shallow and the femoral head or ball slips partially in and out as the dog walks. This laxity or looseness of the hips can lead to debilitating pain and arthritis.

The triple pelvic osteotomy (TPO) is an orthopedic surgery performed to lesson or eliminate the pain and arthritis in dogs with dysplasia. As the name implies three cuts are made in the bone of the pelvis and the bone is rotated usually 20 to 40 degrees so that the cup of the hip joint can cover or capture the ball of the femur such that it can not slip in and out. The cut pelvis is held in place at this angle with a steel plate and screws while the bone heals, usually in three to six weeks.

Hip dysplasia usually involves both hips although one leg may seem worse than the other. A triple pelvic osteotomy ideally is performed on both hips. The operations are staged three weeks apart to let the first side heal. Occasionally, but rarely, they are done at the same time. Not infrequently as few as 7 to 10 days may pass until the second hip is operated on if the surgeon is concerned that arthritis might develop if the second operation is delayed. If arthritis is already present at the time of diagnosis this surgery is not indicated as it is meant as prophylactic surgery to prevent the development of arthritis.

Complications are very rare but have been reported to include implant failure (the plate pulls off or screws), infection, nerve injury, and trouble urinating. These complications are usually temporary or correctable.

Recovery from the TPO is rapid. The dogs are often bearing weight on the leg by the day after surgery and continue to improve over a few weeks. They are restricted to leash walks for 3 weeks at which time radiographs (x-rays) may be made to document healing. When healing of the bone is documented, normal activity is resumed and the dog usually requires no further therapy for pain management and lives a happy pain-free life.

Arthritis FHO/THR
Surgery is not always performed early enough to prevent arthritis and sometimes arthritis is inevitable either from one of the aforementioned conditions or simply the result of age. However it develops arthritis can be debilitating if left untreated. Newer medicines are available that have a higher potency and lower incidence of side effects to make arthritic pets comfortable. Weight control and an exercise program are key elements to successful arthritis management. If medical management fails there are surgical options that vary depending on the joint involved.

For hip arthritis there is the total hip replacement (THR) surgery or a femoral head and neck ostectomy (FHO). The THR is similar to that performed on people where the whole joint is replaced with metal and plastic components. It has a high success rate and low incidence of complications. Even though both hips often have arthritis it may be unnecessary to perform hip replacement on both hips. Complications could include infection, implant failure, and implant loosening. If they occur the implants may have to be replaced or completely removed. Fortunately this happens only rarely. The femoral head ostectomy (FHO) involves the removal of the ball of the hip joint and eventual formation of a "false" or fibrous joint. Pain is eliminated by removing the bone on bone contact that occurs in the arthritic joint. Often both hips must have surgery to make the pet comfortable. Both THR and FHO are considered salvage operations in that the normal joint is replaced or removed. While this most often tremendously improves the quality of life of the pet it would be best to prevent its development. A triple pelvic osteotomy (TPO) done early in a pet’s life can often prevent debilitating arthritis and pain from developing (see advanced techniques)

Arthritis in other joints may also require salvage surgery if medical therapy fails. Arthrodesis of a joint is a surgery where the cartilage is removed and the bones are held together with metal plates or pins until they fuse. This eliminates the motion in that joint but takes all arthritis pain away. Arthrodesis has been successfully performed in the shoulder, elbow, carpus (wrist), stifle (knee), hock (ankle), and toes.

Cancer Surgery
Many people balk when first discussing aggressive options for malignant cancer. They are concerned about their pet’s quality of life postoperatively and any deformity that may result. Osteosarcoma is cancer of bone that often requires amputation for the best outcome. Amputation of the limb is well tolerated by both dogs and cats. They rapidly adjust to bearing weight on the other three limbs and in a few short days are more comfortable than they were before surgery. Bone cancer pain in people is excruciating and we must assume it is the same for animals. They don’t understand their pain and often sleep and eat less because of it. Simply removing this source of pain can dramatically increase their outlook and quality of life.

Osteosarcoma can occur in the ribs as well, requiring removal. Chest wall surgery is less obviously deforming than amputation because the surgeon can remove up to 5 ribs and replace the area with a plastic mesh which is covered by skin as the incision is closed. When the hair coat grows back, the defect is often not apparent. Recovery from surgery is again quite rapid and full activity for the pet is resumed in two to four weeks.

Oral tumors (in the mouth) are common cancers requiring surgery. The tumor types include squamous cell carcinoma (SCC), fibrosarcoma (FSA), and melanoma. SCC and FSA can be cured with surgery alone if diagnosis is early enough and surgery is aggressive enough. Melanomas are aggressive tumors that have often spread by the time of diagnosis but palliative surgery can be performed. Palliative surgery is when surgery does not cure the animal or increase their life span, but does improve their quality of life. The surgery involves removal of the portion of affected bone with a "safety zone" of normal tissue removed as well to ensure complete removal of the cancer. Almost the entire lower jaw or three quarters of the upper jaw can be removed although most tumors require far less, usually involving one quarter of either upper or lower jaw. There often is some cosmetic defect but when the hair grows back it is often minimal. This is especially true in dogs whose pendulous lip is often able to cover large defects. The surgical recovery is again quite amazing as pets are usually eating the next day.

Other examples of cancer surgery include chest surgery to remove lung cancer and abdominal surgery for liver, spleen, and intestinal cancer. These leave no deformity other than a small scar and the patient generally recovers rapidly.