The purpose of saliva is to moisten the mouth and begin the process of food digestion. It is possible for there to be medical problems with the saliva producing glands.
Excessive Salivation (Ptyalism or Sialosis)
There are two main causes for excessive salivation. The dog may be producing excess saliva which is known as ptyalism or sialosis, or the animal may not be able to effectively swallow the normal level of saliva produced. Regardless of the cause, the animal will drool. There are a great number of underlying causes for this, but the most serious is rabies. The vet will eliminate this first before looking for other causes. The cause may be related to the mouth, or it may be a symptom of a more general condition. The underlying cause will need to be treated in order to control the excessive salivation. The lips and face may become inflamed if the skin is not kept relatively dry. It may need to be cleansed with an antiseptic solution.
This is the most common salivary condition in dogs. The saliva accumulates under the skin after the gland or duct has been damaged. It can affect any of the salivary glands but is most common in those in the jaw and under the tongue. In most cases, the exact cause is not determined. The symptoms are dependent on where the saliva has accumulated. There may be a slow growing mass which is often found in the neck. The mass is not painful. If the mucocele is under the tongue then it may not be noticeable until it has had some trauma and starts to bleed. A mucocele in the throat can obstruct the airway which will cause breathing difficulties. If a mucocele becomes infected then there may pain or fever. The veterinarian will extract a sample of fluid from inside the mucocele with a needle. The sample will be used to distinguish the mucocele from other cysts, tumors, and abscesses. It is often treated with surgery, but mucoceles in the neck or under the tongue may be treated with regular draining as surgery may not be an option in these areas. If the mucocele is in the neck, it may be necessary to remove the gland and duct completely. Doing this will avoid future mucoceles obstructing the airway. The veterinarian will recommend the treatment based on the individual animal and its condition.
A fistula is an abnormal opening between two organs, or from an internal organ to the surface. It is rare for fistulas involving the salivary glands to form in dogs. If they do occur, it may be due to an injury to the salivary glands in the cheeks, face, lower jaw and under the tongue. Other possible causes for a salivary fistula are bite wounds, abscess draining or a surgical incision opening. It is important that the fistula is properly identified before treatment. Draining sinuses will need to be eliminated as the problem. If the fistula has been diagnosed then surgery is often needed. The salivary duct may be tied off which usually resolves the issue but sometimes, the gland may need to be removed.
Salivary Gland Tumors
It is rare for salivary gland tumors to be found in dogs. If they are present it is most often in dogs over ten years old. It is possible that poodles and spaniel breeds are genetically predisposed. Salivary gland tumors are often malignant, with adenocarcinomas and carcinomas the most common. They often spread to the lymph nodes and lungs. Radiation treatment, either alone or in conjunction with surgery, is recommended. Tumors that have been removed through a surgical treatment without radiation, ten to recur.
Inflammation of the Salivary Glands
It is rare for inflammation of the salivary glands to be a problem in dogs. When it is found, it is often in addition to another condition or disease. Salivary gland infections can be caused by bites, penetrating wounds, and generalized infections such as distemper, rabies and the virus that, in humans, causes mumps. The symptoms include fever, painful, swollen salivary glands and depression. There may be pus on the surrounding tissue or the mouth due to the discharge from an abscessed gland. A fistula may form if the gland ruptures through the skin. If the inflammation is mild, there may be no need for treatment. The recovery is quick and complete. If there are abscesses present, they will need to be drained and antibiotics will be prescribed. If the infection re-occurs, or if the recovery is not complete within a few days after treatment, the veterinarian will perform a biopsy and some tissue sample tests. On occasion, it may be necessary for the gland to be removed surgically.
Dry Mouth (Xerostomia)
Xerostomia is a condition in which there is a decreased secretion of saliva which then causes dry mouth. This can cause eating difficulties and discomfort. It is not common in dogs, but can be common in humans after radiation treatment for tumors in the head and neck. The radiation may damage the salivary glands. This condition may become more frequently found in cats and dogs due to the increased use of radiation therapy. It may also be caused by disease of the salivary gland, using certain drugs, fever, anesthesia or extreme dehydration. It is important that the underlying cause of xerostomia is identified and treated. There are mouthwashes which can help to relieve the discomfort. If the animal is dehydrated, fluids can be given. If the xerostomia is related to an immune condition, then the appropriate immunosuppressive treatment can be prescribed.