A salivary mucocele, also called a sialocele, is a condition of the salivary glands or ducts that creates a swollen lump in the neck near the jaw, under the tongue, or by the eye. It's a buildup of saliva that may resemble a cyst and, in dogs, it's usually treated with surgery. Learn about salivary mucoceles in dogs so you'll know what to expect if your dog has one.

What is a Salivary Mucocele?

A salivary mucocele is an accumulation of saliva that develops in the tissues near a salivary gland or duct due to leakage. Salivary mucoceles are also called sialoceles or salivary cysts. Though not technically cysts, the fluid buildup causes a swollen structure that resembles a cyst. Salivary mucoceles are soft, fluid-filled, and usually painless. While relatively uncommon in dogs, they're the most common type of salivary problem seen in dogs.

Symptoms of Salivary Mucoceles in Dogs

A salivary mucocele can affect various glands or associated ducts and usually looks and feels like a round lump. These swollen areas are not typically painful in the early stages unless they become large enough to put pressure on another part of the anatomy. Large or infected salivary mucoceles may cause dogs to show non-specific signs of illness, including lethargy and loss of appetite.

The specific signs of a salivary mucocele will depend on the type. There are four types of sialoceles, each named for the location where they occur.

Swelling of the Neck/Jaw (Cervical)

The most common type of salivary mucocele is cervical, which occurs under the upper neck or jaw and originates from the sublingual or mandibular gland or duct. Swelling may occur in the middle of the neck/jaw or off to one side.

Swelling Under the Tongue (Sublingual)

Another common sialocele occurs in the mouth under the tongue and comes from the submandibular gland or duct. The sialocele may be in the center or on one side and can displace the tongue if large enough. This particular type of sialocele is called a ranula or sublingual sialocele. Dogs may also have trouble eating or injure the sialocele when chewing.

Swelling Near the Eye (Zygomatic)

In rare cases, a salivary mucocele develops from the small zygomatic salivary glands located beneath the eye. Facial swelling may appear near the eye and it may cause the eye to bulge.

Trouble Eating, Swallowing, or Breathing (Pharyngeal)

Less commonly, a pharyngeal sialocele develops in the pharynx at the back of the throat and cannot be seen from the outside. This is similar to a cervical sialocele as it stems from the mandibular or submandibular glands or ducts. Pharyngeal sialoceles can make it hard for dogs to swallow and may cause breathing issues.

What Causes Salivary Mucoceles in Dogs?

While the exact cause is unknown, a salivary mucocele is often the result of a traumatic injury to the salivary glands and ducts. Common types of injuries leading to sialoceles include:

• Oral injury from chewing on an object, such as a stick
• Bite wounds from another animal
• Neck injury from pulling on a choke chain or prong collar
  

Other potential causes of salivary mucoceles include:

• Sialolithiasis is a rare condition in dogs that causes stones to form in the salivary glands or ducts. If the stones cause a blockage and rupture, a salivary mucocele may develop.
• Foreign bodies, such as grass awns, can block the salivary glands and lead to rupture, which often causes a salivary mucocele.
• Cancer
  

Any dog breed can develop sialoceles, but German shepherds, dachshunds, poodles, greyhounds, and Australian silky terriers are more often affected. Contact your veterinarian if you notice swelling around your dog's head, face, or neck.

How Do Vets Diagnose Salivary Mucoceles in Dogs

After discussing your pet's history, your veterinarian will perform a physical examination and look closely at the swollen area. They may want to collect a sample to make a definitive diagnosis, which involves three steps:

1. Aspiration: Your vet may use a needle and syringe to collect fluid for testing. Sedation may be necessary depending on the location.
2. Visual Inspection: The fluid from a sialocele is generally clear, yellowish, or blood-tinged in color and slightly viscous like saliva. Your vet may be able to see right away that it is saliva, but will likely send the fluid to a lab for analysis to be certain.
3. Lab Analysis: A veterinary pathologist will analyze the fluid to determine what kinds of cells are present and confirm whether or not the swelling is a sialocele. This analysis can also rule out infections, cancer, and other potential causes for the swelling.
   

How to Treat Salivary Mucoceles in Dogs

Without treatment, a salivary mucocele can become infected and abscessed. Contact your veterinarian if you notice any unusual swelling in the mouth or near the neck, jaw, or eye. A salivary mucocele typically requires draining and surgical intervention.

• Draining: In some cases, a salivary mucocele can be drained to offer temporary relief until surgery can be performed. Most sialoceles will eventually recur after being drained. Continued draining is not recommended as it can lead to inflammation or infection.
• Surgery: Definitive treatment of a salivary mucocele involves surgical removal of the affected salivary glands and associated ducts. This is a delicate procedure that is typically performed by a board-certified veterinary surgeon. Drains may be temporarily placed at the surgical site to prevent new fluid accumulation.

Prognosis for Dogs With Salivary Mucoceles

Most dogs with salivary mucoceles recover well from salivary gland removal surgery, and complications are rare. Your veterinarian will send your dog home with medications and instructions for basic home care. Follow your veterinarian's recommendations for post-operative care. Give medications as directed and keep the incision, drain sites, and any bandages clean and dry. Bring your dog back to the vet for follow-up visits as necessary.

How to Prevent Salivary Mucoceles

Salivary mucoceles are uncommon in dogs, but pet parents can still take steps to prevent injuries . and illness. Here are a few ways to keep your dog healthy:

• Avoid using choke chains or prong collars on your dog.
• Train your dog to walk on a loose leash to prevent injuries from pulling.
• Supervise your dog when gnawing on chews and toys,
• Keep your dog from chewing on sticks or other unsafe objects.

Contact your veterinarian if you notice an injury or swelling near your dog's mouth or neck. Treatment of a fresh injury may prevent the development of a salivary mucocele.