Jennifer E. Rawlinson, DVM, DAVDC; John R. Lewis, VMD, FAVD, DAVDC
The following cases will discuss the intricacies of dealing with patients affected by dental problems and concurrent systemic diseases. Also, the role of dental disease in the development or exacerbation of systemic disease will be discussed. Approaches to some of the more common real-world scenarios will be discussed in this interactive lecture.
Case 1: 12 yr FS Min. Poodle with Severe Periodontal Disease and Mitral Valve Insufficiency
More and more evidence suggests that an unhealthy mouth may result in disease elsewhere in the body of companion animals. DeBowes, et al., found an association between severity of periodontal disease and histopathological changes in kidney, myocardium (papillary muscle) and liver.1 Rawlinson, et al., showed that increases in concentrations of systemic inflammatory mediators were positively correlated to the severity of periodontal disease.2 This begs the question in our case example: "Did the dental disease contribute to other concurrent diseases and will it contribute to further exacerbation of disease at distant sites?"
Inflammatory mediators arise from the interaction between subgingival bacteria and the immune response to these "periodontopathogens". The subgingival component of the disease is treated by periodontal debridement using ultrasonic and hand scalers, and therefore, general anesthesia is an important aspect of treatment. The difficulty with general anesthesia in these cases is that the population of patients with the most severe periodontal disease are often the oldest patients with other debilitating problems, such as cardiac, renal, hepatic and respiratory disease. Therefore, "anesthesia free dentistry" has increased in popularity as a direct result of clients fears of general anesthesia. There are many inherent problems with "anesthesia free dentistry", including: 1) Subgingival cleaning is difficult or impossible in the awake patient, and the subgingival area should be the area of primary focus when attempting to prevent systemic effects of bacteremia. 2) Thorough polishing after scaling is very important to remove microetches and to prevent more rapid accumulation of plaque and calculus. Polishing is nearly impossible in the awake patient. 3) It is impossible to obtain dental radiographs without anesthesia, and without dental radiographs, subgingival pathology is missed. 4) Since dogs have 42 teeth and cats have 30 teeth, there is a very good chance that at least one tooth will require extraction or advanced periodontal therapy, which is not possible without general anesthesia. 5) A thorough examination of the entire oral cavity should be part of the dental cleaning, and evaluation of the caudal oropharynx and tonsillar area is impossible in the awake patient.
Therefore, rather than anesthesia free dentistry, each case should be assessed of risk vs. benefit on an individual basis. A thorough preoperative work-up in a 12-year-old poodle with mitral valve disease may include complete blood count, chemistry screen, urinalysis, chest radiographs, cardiology consultation (including BP, ECG, and echocardiogram). If evidence of cardiac failure is seen on chest radiographs, the perceived benefit of the procedure would need to be quite high to outweigh possible risks of a long anesthetic procedure. If no evidence of cardiac failure is present, this may be the time to proceed with an elective procedure since this patient may never be as good of an anesthetic patient as she is currently. Some cases with a large perceived risk will do fine and some cases with minimal perceived risk will have complications, but fatalities associated with elective dental cleanings at our hospital occur in less than approximately 0.2% of cases.
Another preoperative evaluation necessary in a patient of this signalment is palpation of the neck for evidence of tracheal collapse. Though cough on palpation is not specific, it is a sensitive test of tracheal collapse. Exacerbation of a lax dorsal tracheal membrane by a cuffed endotracheal tube may be the most profound risk associated with a dental cleaning in a miniature poodle, Yorkshire terrier, or Chihuahua.
Should patients with valvular heart disease be placed on preoperative or intraoperative antibiotics? This is a very controversial topic in human dentistry. For years, patients with valvular disease were preemptively treated with prophylactic antibiotics, but in 2007, the American Heart Association (AHA) updated its recommendations based on a review of relevant literature regarding procedure-related bacteremia and endocarditis, in vitro susceptibility data of the most common microorganisms which cause infective endocarditis (IE), results of prophylactic studies in animal models of experimental endocarditis, and retrospective and prospective studies of prevention of infective endocarditis. The updated recommendations of the AHA are: 1) The committee concluded that only an extremely small number of cases of IE might be prevented by antibiotic prophylaxis for dental procedures even if such prophylactic therapy were 100 percent effective. 2) IE prophylaxis for dental procedures should be recommended only for patients with underlying cardiac conditions associated with the highest risk of adverse outcome from IE. 3) For patients with these underlying cardiac conditions, prophylaxis is recommended for all dental procedures that involve manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa. 4) Prophylaxis is not recommended based solely on an increased lifetime risk of acquisition of IE. 5) Administration of antibiotics solely to prevent endocarditis is not recommended for patients who undergo a genitourinary or gastrointestinal tract procedure. These changes are intended to define more clearly when IE prophylaxis is or is not recommended and to provide more uniform and consistent global recommendations.3
Case 2: 14 yr FS DSH with Anorexia, Chronic Renal Failure, Hyperthyroidism, and HCM
Anorexia places the practitioner between a rock and a hard place especially when presented with the anorexic cat with multiple metabolic abnormalities. The first assessment in determining the risk-benefit ratio is what is meant by "anorexic". Does the patient still eat but show evidence of discomfort upon eating dry food? Does the patient maintain its weight on canned food? Or is this a case of complete anorexia with documented weight loss? Surprisingly most dental disease, even in its most severe forms, does not result in complete anorexia, so other medical issues such as increasing BUN and creatinine may be to blame. Having said that, widespread resorptive lesions or oral neoplasia may result in partial anorexia, and severe stomatitis may cause complete anorexia in some cases. Periodontal disease in the absence of stomatitis, although resulting in halitosis and recession, rarely affects appetite. Sometimes it can be a challenge to determine if oral disease is the cause of anorexia, but reluctance of the patient upon oral examination may provide some clues. Patients with newly diagnosed hyperthyroidism should be placed on Tapazole to obtain an euthyroid state ideally prior to anesthesia. However, this is not always feasible if complete anorexia is thought to be related to dental disease.
If a feline patient is anorexic prior to a procedure involving significant oral surgery, placement of a feeding tube is recommended to ensure proper caloric intake during healing, and this also provides clients with an easier means of administering medications. Both esophagostomy and gastrostomy tubes are equally effective for maintenance of body weight, ease of owner management, and complication rates.4 Esophagostomy tubes are easy to place and when complications occur they tend to be less severe.
Patients suffering from both cardiac and renal disease may benefit from placement of a central line to monitor central venous pressures during the procedure. It is not uncommon for a long anesthetic procedure to result in an acute exacerbation of chronic renal disease, and monitoring of central venous pressures may allow for the optimum amount of fluids to be delivered without resulting in excessive load on the heart.
Case 3: 1 Yr FS DSH with Head Trauma Associated with High-Rise Syndrome
A one year old cat presents conscious but nonambulatory and with significant epistaxis and oral bleeding. The patient was found on the street four stories below the client's balcony. Once determined to be stable, a thorough examination reveals evidence of a left femoral fracture and fracture of the right maxilla and right mandibular body. Chest radiographs are taken to assess for diaphragmatic hernia, pneumothorax and pulmonary contusions, with the realization that the full extent of contusions may not be fully apparent until later. Assessment of neurological status is important prior to pursuing treatment of fractures, and will be discussed as related to this case.
Advanced diagnostics such as CT should be considered in cases of high-rise trauma. In this case, CT revealed findings that would not have been appreciated by other modalities. Common and uncommon orthopedic trauma of the head associated with high rise syndrome will be discussed, as well as long-term sequela of these types of injuries.
Case 4: 1.5 Yr MC Shetland Sheepdog with Palatal Defect from Nasal Fungal Infection
A young Sheltie presents with a significant acquired mid-palatal defect resulting from a needle foreign body. Persistent mucopurulent bilateral nasal drainage unresponsive to antibiotic therapy warranted a complete work-up including a CT, rhinoscopy with biopsy, bacterial culture with sensitivity, and fungal cultures. A diagnosis of nasal Aspergillosis compounded by a multiple antibiotic resistant Pseudomonas was reached. Severe destruction of the hard palate, nasal turbinates, nasal septum, and regional soft tissue was apparent on CT. After extensive therapy for treatment of Pseudomonas and Aspergillosis, the acquired palatal defect needed debridement and repair. Though the dog's clinical signs of infection were resolving, preoperative regional bacterial culture with sensitivity showed continued growth of Pseudomonas and biopsy results were questionable regarding complete resolution of the Aspergillosis infection.
Many approaches to palatal repair have been described.5 Choice of repair strategy depends heavily on size and shape of defect, health of underlying soft tissue and bone, vitality of regional vascular supply, and owner commitment (both physical support and financial). The number of past attempts at repair is also an important consideration as the chance of a successful repair decreases dramatically with increasing number of surgical interventions due to disruption of regional vascular supply and loss of healthy/complete regional soft tissue. Due to the persistence of regional infection and limited owner finances, surgical debridement and placement of a palatal obturator was selected as treatment for this palatal defect.
Palatal obturators are individually fashioned thin acrylic "plugs" that are placed into palatal defects to provide a complete barrier between the oral cavity and the nasal passage. Healthy surrounding tissue is necessary to provide support for retention of the obturator. All necrotic tissue must be debrided and the wound completely healed prior to obturator placement. Fashioning of the obturator requires an impression of the defect to be sent to a dental laboratory for device fabrication (in-house device fabrication is possible in experienced hands). Though most obturators are designed for unsupported retention some cases will require a little creativity for additional support. Owners should be aware that obturator placement will require daily oral rinsing and semi-annual to annual anesthetized cleaning with possible obturator replacement.
Case 5: 10 Yr FS DSH with Gingivostomatitis and Diabetes Mellitus
An elderly cat with a history of refractory gingivostomatitis (GS) develops diabetes mellitus (DM) not controlled by routine insulin therapy. The cat developed GS at age 6 yr; the disease had been managed by caudal mouth extraction and progressively increasing levels of methylprednisolone (cat's personality made oral dosing impossible). It was unclear if the development of DM was primary or iatrogenic due to the high dose of steroid given to the cat to control the GS. Initial attempts to obtain good glycemic control with insulin were unsuccessful.
This case brings out many salient points when dealing with cats suffering from GS and a complicating systemic disease. Medical management will only mask the GS, and unfortunately, many cats receiving only medical management will slowly become less responsive to antibiotic and steroidal medications. To keep their patients comfortable and eating, doctors respond with increasing dosage and frequency of these medications. The most common side effects to frequent, high doses of steroid and antibiotics are diabetes mellitus, recurrent infections, antibiotic resistance, and muscle wasting. Many cats at this point in therapy present underconditioned, dehydrated, and unkempt.
Management of chronic GS through dental extractions has been shown to be successful in reducing if not eliminating future medical management in 93% of cases.6 In order to achieve success, it is sometimes necessary to remove ALL tooth material. In the case presented, though a caudal mouth extraction had been performed intraoral dental radiography revealed multiple roots remaining under very inflamed regional gingiva and mucosa. Though it was unknown whether high and frequent dosing of methylprednisolone led to the development of DM, it has been shown in humans that there is a bidirectional relationship between diabetic glycemic control and periodontitis (inflammation of tissue surrounding the teeth).7 Reduction of infection/inflammation leads to better glycemic control and better glycemic control decreases the risks of infection. Complete dental extraction including all retained roots drastically decreased this patient's need for chronic medical management of the GS and glycemic control was achieved after 1 month with a very low dose of insulin therapy. Notably, after extractions the owner was able to maintain the cat on 5 mg of prednisolone orally every other day.
1. DeBowes LJ, et al. J Vet Dent 1996;13(2):57-60.
2. Rawlinson JE, et al. Proc. 19th Annual Vet Dent Forum 2005: 429.
3. Wilson W, et al. J Am Dent Assoc. 2007;138(6):739-45, 747-60.
4. Ireland LM et al. J Amer Anim Hosp Assoc 2003;39(3):241-6.
5. Harvey CE. Compendium Small Anim. 1987; 9(4):404-18.
6. Hennet P. J Vet Dent. 1991;14(1):15-21.
7. Mealey BL, et al. Dent Today. 2003; 22(4):107-13.