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Below is information about the structure and function of the canine tongue, teeth and mouth. We will tell you about the general structure, how they work in dogs, common diseases that affect these areas and common diagnostic tests performed in dogs to evaluate the tongue, teeth and mouth.
What Are the Tongue, Teeth and Mouth?
A dog’s tongue is an elongated, mobile, muscular organ. It is the chief organ responsible for taste and obtaining food. It also aids in the chewing and swallowing of food. The teeth are highly specialized structures that tear, cut and grind food into pieces small enough to swallow. Teeth also serve as weapons of offense and defense for dogs. The mouth is the entrance to the gastrointestinal tract. The mouth, teeth and tongue are collectively termed the oral cavity.
Where Are the Tongue, Teeth, and Mouth Located?
What Is the General Structure of the Tongue, Teeth and Mouth for Dogs?
Pulp is the innermost tissue of the tooth. It is the only soft tissue of the tooth and resides in the center of tooth, especially towards the root end. It consists of connective tissue, blood vessels and nerves. The blood vessels nourish the tooth, and the nerves transmit sensations of pain, coldness, or heat to the brain.
Dentin is a hard, yellow substance that surrounds the pulp. It makes up most of a tooth and gives the tooth an inner ivory or creamy color. Dentin is harder than bone and consists mainly of mineral salts and water. It is formed by cells called odontoblasts.
Enamel overlies the dentin on the crown of the tooth. It forms the outermost covering of the crown. It is the hardest tissue in the body. It enables a tooth to withstand the pressure placed on it during chewing. Enamel consists of mineral salts and a small amount of water. It is usually a pearly-white color.
Cementum covers the dentin along the root of the tooth. In most cases, the cementum and enamel meet where the root ends and the crown begins. Cementum is as hard as bone, and it consists mainly of mineral salts and water.
The root is the portion of the tooth that lies below the gum and is embedded in the alveolus or socket. Some premolar and molar teeth have more than one root. Once teeth are fully erupted in the animal, they cease growing.
What Are the General Functions of the Tongue, Teeth, and Mouth?
What Are Some Diseases of the Tongue, Teeth and Mouth in Dogs?
Glossitis is inflammation of the tongue. It may occur alone, or be associated with a generalized inflammation of the soft tissues of the mouth (stomatitis), inflammation of the gums (gingivitis), or of the lips (cheilitis). Causes of glossitis and stomatitis in the dog include the ingestion of foreign bodies (e.g. needles, fish hooks, tacks), exposure to chemicals and caustic agents, and irritating plants. Infectious diseases, particularly bacteria, the viruses that cause upper respiratory infections (e.g. adenovirus, distemper virus), and fungal agents (e.g. candidiasis, blastomycosis) can cause inflammation and ulceration of the tongue. Glossitis and stomatitis in the dog may also occur as a component of immune-mediated diseases, metabolic diseases, nutritional disorders, poisoning with certain toxins.
Ulcerations can develop on the tongue in association with systemic diseases such as kidney failure and certain cancers of the body. Ulcerations can also occur with a peculiar disease of dogs called eosinophilic granuloma or eosinophilic stomatitis. Collagen degeneration and the infiltration of white blood cells called eosinophils lead to ulceration and growths on the tongue and in other areas of the mouth, especially in the Siberian husky and Cavalier King Charles spaniel. The cause of this disease is not entirely understood.
Tumors or neoplasia may also occur on the tongue. The most tumors of the tongue in dogs are malignant, and include melanomas, squamous cell carcinomas, and fibrosarcoma. Oral papillomatosis is a contagious disease of young dogs caused by the papillomavirus. The virus causes cauliflower-type warts to develop all over the surfaces of the oral cavity. Most of these warts regress over several weeks on their own.
Trauma may also occur to the tongue. Injuries may include burns, lacerations, puncture wounds, and bite wounds.
Abnormal numbers of teeth and retained deciduous may occur. Brachycephalic dogs with very short, blunt faces may have fewer teeth and shorter jaws that other dogs. Retained deciduous teeth are baby teeth that fail to fall out on their own. Any baby tooth that persists beyond six months of age is considered abnormal.
Abnormal bite may occur in dogs. If the upper and lower teeth to do line up properly, the condition is called a malocclusion. Sometimes the upper teeth hang out further in the front of the mouth than the bottom teeth, and sometimes the opposite occurs. Abnormal bites may lead to abnormal wearing of the teeth, chronic trauma to gums, and periodontal disease.
Periodontal disease is the development of plaque or tartar on the teeth, with secondary inflammation of the gums (gingivitis) and other supporting structures (periodontitis). Dental plaque is a yellow/gray/green substance that coats the surface of the tooth. It is composed of bacteria, proteins from saliva, and various other substances. Plaque is a major problem for animals because they do not routinely brush their teeth. Untreated plaque leads to infections around the teeth and potentially the loss of affected teeth.
Tooth root abscesses can occur in any tooth, but are usually associated with the premolar or molar teeth. They occur more often in upper teeth, than in lower teeth. They are characterized by the accumulation of pus around the root of the tooth. When upper teeth are involved swelling may occur on the face, just beneath the eye. If the abscess ruptures to the outside, a small draining hole may be seen on the face.
Trauma to the teeth is common in some animals. Some teeth become broken or cracked. Other teeth wear down over years of continuous use. Abrasions may also occur from chewing sharp objects. Clinical signs associated with dental trauma vary, depending upon whether the pulp cavity is exposed. Exposure of the pulp cavity is often painful.
Tumors near the teeth may develop from the supporting or surrounding tissues. An epulis is a benign growth than arises from periodontal tissue. It appears as a pink mass arising from the gums that can go so large as to cover one or more teeth. Ameloblastoma and odontoclastic tumors may also develop near the teeth.
Stomatitis is an inflammation of the oral mucosa (lining of the mouth) and other soft tissues of the mouth. It has many potential causes, including all the causes of glossitis outlined above. Bacterial (e.g. spirochetes), viral (e.g. canine adenovirus, canine distemper virus), and fungal infections may cause stomatitis. Some bacteria that are normal residents of the mouth may take advantage of inflammation in the mouth to create significant infections.
Tumors of the mouth are often malignant in dogs and usually involve the soft tissues of the mouth. Tumors of the bones of the mouth are also possible, but occur less often. Examples include the malignant melanoma, squamous cell carcinoma, fibrosarcoma, and osteosarcoma.
A ranula is a swelling that develops under the tongue from the formation of a cyst of the sublingual salivary gland. The swelling may become large and inflamed, causing the tongue to be pushed upwards or to the side. The dog may have difficulty eating, may drool or exhibit excessive licking, and may act painful when the mouth is opened or manipulated. Cysts may also develop from other salivary glands and impinge upon the structures of the mouth.
What Types of Diagnostic Tests Are Used to Evaluate the Tongue, Teeth, and Mouth?
Veterinarians use a number of different tests to evaluate the tongue, teeth and mouth. A thorough oral examination using an external light source is the single most important test in evaluating structures in the oral cavity. Many times tranquilization or even anesthesia is necessary for a thorough evaluation of all of the oral structures. Oral examination is followed by a thorough physical examination in order to detect other signs of illness or organ involvement.
Depending upon the clinical signs, the age and overall health of the dog, and the findings on oral and physical examination, other specific tests may be recommended by your veterinarian. Tests designed to evaluate disorders of the tongue, teeth and mouth include the following:
