by Dr. Daniel T. Carmichael
Feline Dental Problems
Dental disease is common in domestic felines. In fact, dental problems are the most common disease that we see in cats, and many dental problems are painful. The most common sign of pain in cats, however, is no sign at all. By diagnosing and rendering appropriate treatment, we can eliminate pain and afford our feline patients a better quality of life.
The vast majority of feline dental problem can be grouped into one of five disease categories: Periodontal disease, feline odontoclastic resorptive lesions (FORL), fractured teeth, feline gingivitis/stomatitis syndrome, and oral neoplasia (cancer).
Kittens are born adentuous (without teeth). By one to two weeks of age, the deciduous or temporary teeth begin to erupt. The six-week-old kitten should have a full complement of 26 deciduous teeth. Between four and five months-of-age the deciduous teeth will be shed, and the permanent teeth will erupt. By six months of age, a total of 30 permanent teeth will have erupted that comprise the complete feline adult dentition. These 30 teeth include 12 incisors, 4 canines, 10 premolars, and 4 molars. If the primary dentition fails to be shed by the time the permanent tooth erupts, a condition called “retained deciduous teeth” occurs.
The dental formula of the cat is as follows:
Cat: Deciduous teeth: 2X (3/3 i, 1/1 c, 3/2 pm) = 26
Permanent teeth: 2X (3/3 I, 1/1 C, 3/2 PM, 1/1 M) = 30
Feline teeth are “hollow” and the hollow chamber inside the tooth– the pulp cavity (root canal)– contains the blood vessels, nerves and lymphatics that comprise the dental pulp. The pulp tissues communicate with the rest of the body through multiple small openings located at the root apex (tip of the root). The pulp chamber is surrounded with a tissue called dentin. Dentin is a hard tissue that is produced by odontoblasts, and forms the bulk of the tooth’s structure. As the tooth ages the odontoblasts continue to produce dentin, causing the dentin to thicken and the pulp chamber to narrow. On the crown of the tooth, which is the part of the tooth visible above the gum line, a protective layer of enamel covers the dentin. The root dentin is covered by cementum, which is where the periodontal ligament fibers insert.
The periodontium consists of the structures “around the tooth” that function to attach the tooth in the mouth. The periodontium consists of the gingiva, the alveolar bone, the cementum, and the periodontal ligament.
Pathologic conditions are common in the mouth of the cat. A broad classification of feline dental pathology includes disease conditions that affect the teeth, and disease conditions that affect the structures around the teeth. The common “tooth lesions” in cats are feline odontoclastic resorptive lesions and dental fractures. The common “around the tooth lesions” diseases include periodontal disease (gingivitis, periodontitis), and the severe inflammatory condition called feline gingivitis/stomatitis syndrome (lymphocytic-plasmacytic stomatitis). The lesions of feline gingivitis/stomatitis syndrome include inflammation of the periodontal structures as well as the oral mucosa (and sometimes the lips and tongue). Oral neoplasia (cancer) can affect soft tissue, bone, and tooth structure.
Equipment for Treating Dental Disease in Cats
A minimum amount of equipment that is necessary for performing routine dental care in feline patients includes a high-speed dental drill and a dental x-ray machine. Attempting to accurately diagnose and treat the most common dental problems in cats without intraoral radiography and high-speed drills puts both the practitioner and patient at a disadvantage. No small animal practice that performs dental procedures should be without this equipment.
Feline Periodontal Disease
Periodontal disease is very common in cats. Left untreated, periodontal disease can cause oral pain, oral abscess formation, osteomylitis, tooth loss, and vital body organ infections from bacteremia. Most cases of advanced periodontal disease in felines could have been preventedthrough a program of early disease detection and appropriate treatment.
Periodontal disease is caused by the presence of plaque bacteria on the teeth and the host’s response to that bacteria. The combined effects of bacterial toxins and the products of the host’s inflammatory response cause the periodontal tissues to become inflamed, and if the not checked by professional intervention, destroyed. An “over-response” by the host’s immune system may explain why some individual patients or certain breeds (Maine Coon, Ragdoll, Oriental Breeds, and others) exhibit rapidly progressing and/or more severe disease.
The early stage of periodontal disease is characterized by halitosis and gingivitis. Because the cat’s gingiva is very narrow, this gingivitis may not appear dramatic—but it is! This early stage of periodontal disease, gingivitis, is one of the few oral disease conditions where we can perform treatment and return things to a good state of health. Especially in cats, we need to look for this at an early age. It is not uncommon to see cats at 6 or 8 months of age with significant oral inflammation, the so-called juvenile-onset gingivitis. If left untreated, by the age of 12 -24 months this may quickly progress to irreversible periodontitis. Treatment recommendations for cats with early stage periodontal disease include frequent professional prophylaxis, and daily homecare.
Once periodontal disease has progressed into the more advanced stages, periodontitis, the treatment plan is geared more toward damage control than prevention. The loss of periodontal tissue (gingival, bone, periodontal ligament) that occurs with periodontitis is, in most cases, irreversible. In cats, advanced periodontal disease can quickly progress to a point where extraction is the only valid treatment option remaining. If the goal is to save teeth, aggressive treatment combined with daily homecare is required. If advanced periodontal treatment (flap surgery, etc.) is being considered, make sure you have good radiographic documentation to rule out feline odontoclastic resorptive lesions. The presence of FORLs will doom your periodontal treatment to failure. Clinically, there are very few cases where advanced periodontal surgery is warranted in felines. These select cases usually involve the canine teeth that have relatively longer roots. Because the roots of the incisors, premolars and molars rarely exceed 7-8 mm., periodontal pockets of similar depth that could reasonably be managed in a dog or in a human doom these short feline teeth for extraction. (Figure 3) There is a fine line between prophylaxis and exodontia in the cat.
Treatment Recommendations for Feline Periodontal Disease
- Yearly or Semi-Annual Examination of the Oral Cavity Under General Anesthesia
Dental prophylaxis, complete oral examination, and intraoral radiographs as indicated to evaluate for other pathology. Be prepared to perform extractions as needed. It is not uncommon to discover more pathology than you bargained for after the cat has been anesthetized, radiographed, and fully examined.
- Daily Homecare
Daily tooth brushing is the best thing you can recommend for pet owners to do at home to promote good oral hygiene. A daily tooth brushing is necessary because plaque bacteria can colonize on teeth in a period of 24-36 hours. This means that within a just a few days following your prophylaxis, the teeth are already starting to accumulate the plaque bacteria that cause periodontal disease. If nothing is done to prevent or retard the accumulation of plaque, the periodontal disease process will continue unchecked.
- Dental Diets
There are several commercial diets that have been shown to significantly reduce plaque and tartar when fed compared to “regular” dry food diets. This isn’t just marketing hype—studies document significant reduction in the plaque index for the foods tested. Specifically these foods are IAMS Daily Dental Care, Hills T/D (prescription diet) and Oral Care, and Friskies Dental Diet. With the incidence of periodontal disease so high, there are few reasons why anyone would not want to provide a diet that promotes good periodontal health.
- Other Products
Oral rinses, sprays, and other such products also have a role in homecare. These products are sometimes used after oral surgery when brushing is not appropriate. In pets that refuse brushing, these products may be the only kind of homecare possible.
Tooth fracture occurs most commonly in cats following trauma. When a tooth has been broken, the pulp chamber is often exposed to the oral environment. The pulp exposure can be visualized on oral examination as a pink (vital pulp) or black (necrosed pulp) spot at the site of exposure.
Any time a pulp cavity is exposed, it must be treated. Exposed pulp is painful to the animal and can lead to periapical osseous (bone) infection. There are two treatment options whenever an exposed pulp is encountered. The first is to extract the tooth; extraction fulfills the treatment goals of preventing pain and infection, as long as no broken roots are left behind. A second option is the save the tooth by performing endodontic therapy (root canal) if an intraoral radiograph shows the tooth to be treatable. Teeth with evidence of resorptive lesions are not candidates for endodontic therapy and should be extracted.
Feline Odontoclastic Resorptive Lesion (FORL)
Feline odontoclastic resorptive lesions (also known as neck lesions, cervical line erosions, and cat cavities) are the most common dental problem in cats. Studies worldwide have shown incidence rates in cats presented for dental problems of up to 75%! Feline odontoclastic resorptive lesions (FORL) are painful. Clinical signs associated with FORL include anorexia, drooling, refusal to eat the hard portions of the diet, and overall malaise. The most common sign of pain in cats, however, is no sign at all.
On oral examination, these lesions are often associated with a localized, cherry-red, sometimes-hyperplastic area of gingivitis. The most commonly affected teeth are the mandibular third premolars, the maxillary third and fourth premolars, and the canine teeth; however, all 30 teeth in the cat’s mouth are at risk. FORL lesions can be demonstrated on oral examination by gently brushing the suspected lesion with a thin wisp from a broken wooden “Q-tip”. Gentle stimulation of these lesions invokes a strong jaw-chattering response.
Restoration (fillings) of FORL is controversial. The controversy lies in the fact that the majority of restorations fail. With these poor results in mind, and the etiology of this disease unknown, it has been the opinion of the majority of the veterinary dental community that all teeth affected with FORL be extracted. A crown amputation procedure has been described for “extraction” of teeth exhibiting FORL. In this procedure, the crown of the tooth is removed while intentionally leaving the roots behind. Cats with associated periodontal disease or gingivitis/ stomatitis should never be considered candidates for crown amputation. Dental radiography is essential for accurate diagnosis and treatment planning.
Probably the most frustrating oral disease we see in our clinical practice is feline gingivitis/stomatitis syndrome (FGS). Cats will present with clinical signs of partial to complete anorexia, drooling, halitosis, and oral pain. Physical exam will show various signs of gingivitis (inflammation of the gingiva), stomatitis (inflammation extending to the oral mucosa), palatitis, faucitis (inflammation of the caudal fauca), glossal ulceration, and pharyngitis. There is often an associated submandibular lymphadenopathy (swollen glands). When a cat presents with clinical signs compatible with this syndrome, a complete diagnostic workup is necessary.
To start with a complete physical exam, CBC/Chemistry, feline serology and other ancillary tests as indicated should be performed. The results of the blood tests are usually unremarkable, except for a hyperproteinemia resulting from a hypergammaglobulinemia. The feline retrovirus infections are certainly associated with oral inflammation, but most cats with FGS are retrovirus negative.
Next, a dental prophylaxis should be performed. All teeth exhibiting feline odontoclastic resorptive lesions and all teeth with end-stage periodontal disease should be extracted. Also, any root tips or fragments need to be removed. Never leave root tips behind in these cases. Dental radiographs are essential when evaluating for retained roots. A biopsy should be performed, including samples from the gingiva and affected areas in the pharynx.
The results of the biopsy often show “lymphocytic-plasmacytic stomatitis”. This is not a diagnosis. This is the typical histological picture whenever cats have chronic inflammation. The histopathological results that we may see to alter our treatment include eosinophilic granuloma, autoimmune diseases, or neoplasia.
Following dental prophylaxis, the owners need to be counseled to provide daily home care. Most cases of feline gingivitis are thought to result from an over- exaggerated immune response to plaque bacteria. In some cases, simply keeping the oral environment clean will keep this condition in check.
When the biopsy results show lymphocytic/plasmacytic inflammation and home care is not working, treatment options include medical or surgical management. Surgical treatment, involving extraction of all teeth caudal to the canines, has been shown to be 85% effective in curing this disease. This is a labor-intensive procedure, and will not be successful if any root fragments are left behind. In some cases, areas of inflamed or infected bone surrounding the alveolus also need to be removed. It is difficult, if not impossible, to perform this procedure without dental x-rays and high-speed drills.
Feline Oral Cancer
Unfortunately, the vast majority of tumors found in the mouths of cats are malignant and carry a poor prognosis. Over 20 different types of cancer have been reported to occur in the oral cavity of felines, although only a few are observed commonly. Among the more common feline oral neoplasms are squamous cell carcinoma (SCC), fibrosarcoma, lymphoma, and malignant melanoma. Squamous cell carcinoma is by far the most common, accounting for about 70% of feline oral neoplasms. It is of extreme importance to identify the tumor type and commence treatment early in the course of disease if a favorable treatment outcome is to be achieved. In the majority of cases, however, a clinical cure is not possible.
Any swelling (soft tissue or bony) or abnormal appearance of tissue in the oral cavity must be considered suspicious for neoplasia. A common but very subtle presentation of oral neoplasia is when a tooth can be extracted too easily. The results of the biopsy should be discussed with a veterinary oncologist to offer up-to-date treatment options and prognosis.