Geriatric veterinary dentistry: how old is too old to make it right?

A second set of eyes helps monitor the anesthetized patient. (All photos courtesy of Dr. Jan Bellows)

Pediatric and adolescent companion animal dentistry focuses largely on the diagnosis and treatment of congenital and developmental oral issues, including persistent and retained deciduous teeth, supernumerary teeth, orthodontic malpositions, and malocclusions. Mature canine and feline dentistry deals primarily with fractured teeth, tooth resorption, and periodontal disease (PD) prevention.

Senior dental problems center around moderate to advanced PD and both benign and malignant oral masses. In addition, the veterinarian and staff must be comfortable tailoring anesthesia to the individual patient, with attention to concurrent conditions, as well as diligent monitoring during and after procedures.

Periodontal disease in senior patients

The degree of PD severity relates to a single tooth. It is important to keep in mind that a patient may have teeth with different stages of PD. Typically, geriatric dental patients have multiple stages of PD occurring simultaneously. Therefore, intraoral imaging is essential, along with probing to determine the tooth's support. Treatment options for PD include:

• Dental scaling and polishing for patients with stage 1 PD

• Root planing and locally applied antimicrobials for pockets less than 5 mm in patients with stage 2 PD

• Extraction for teeth affected by advanced PD and those with moderate PD for which the owner cannot perform adequate home care (Figures 1 and 2). Senior dogs and cats with advanced PD affecting the entire mouth often require full-mouth extractions. Fortunately, these patients usually thrive once their mouth is pain-free.

Figure 1A. Marked periodontal disease and subsequent caudal ulceration in a 12-year-old Yorkshire terrier.

Figure 1B. Resolution after full-mouth extraction.

Figure 2A. Periapical lucencies surrounding the roots of the left maxillary first and second molars consistent with advanced periodontal disease, plus periapical lucency surrounding the roots of the fourth premolar consistent with advanced endodontic disease.

Figure 2B. Postoperative radiograph confirming complete extraction.

Stages of periodontal disease

Normal (PD 0): clinically normal; no clinically evident gingival inflammation or periodontitis

Stage 1 (PD 1): gingivitis only without attachment loss; normal height and architecture of the alveolar margin

Stage 2 (PD 2): early periodontitis; less than 25% attachment loss as measured by probing the clinical attachment level, by radiographic determination of the distance of the alveolar margin from the cementoenamel junction relative to the length of the root, or by the presence of stage 1 furcation involvement in multirooted teeth

Stage 3 (PD 3) (Figure 3): moderate periodontitis; 25% to 50% attachment loss as measured by probing the clinical attachment level, by radiographic determination of the distance of the alveolar margin from the cementoenamel junction relative to the length of the root, or by the presence of stage 2 furcation involvement in multirooted teeth

Figure3A: Stage 3 periodontal disease in a cat.

Figure 3B: Stage 3 periodontal disease a dog.

Stage 4 (PD 4) (Figure 4): advanced periodontitis; more than 50% attachment loss as measured by probing the clinical attachment level, by radiographic determination of the distance of the alveolar margin from the cementoenamel junction relative to the length of the root, or by the presence of stage 3 furcation involvement in multirooted teeth

Figure 4A: Stage 4 periodontal disease in a cat.

Figure 4B: Stage 4 periodontal disease in a dog.

Oral masses in senior patients

Types of tumors

Oral masses are frequently noted in geriatric dogs; they are less common in cats. Commonly diagnosed oral masses include the following:

• Adenocarcinoma: an invasive, malignant epithelial neoplasm derived from glandular tissue of the oral cavity, nasal cavity, or salivary tissue (major or accessory) with moderate metastatic potential.

• Fibrosarcoma: an invasive, malignant mesenchymal neoplasm of fibroblasts with a low metastatic rate; a distinct histologically low-grade, biologically high-grade variant is often found in the oral cavity.

• Hemangiosarcoma: a malignant neoplasm of vascular endothelial origin characterized by extensive metastasis; it has been reported in the gingiva, tongue, and hard palate.

• Malignant melanoma: an invasive, malignant neoplasm of melanocytes or melanocyte precursors that may or may not (amelanotic) be pigmented, with a marked tendency to metastasize.

• Multilobular bone tumor: a potentially malignant and locally invasive neoplasm of bone that more commonly affects the mandible, hard palate, and flat bones of the cranium with a multilobular histologic pattern of bony or cartilaginous matrix surrounded by a thin layer of spindle cells that gives it a near-pathognomonic radiographic “popcorn ball” appearance; also called multilobular osteochondrosarcoma, multilobular osteoma, multilobular chondroma, chondroma rodens and multilobular osteosarcoma.

• Osteosarcoma: a locally aggressive, malignant mesenchymal neoplasm of primitive bone cells that have the ability to produce osteoid or immature bone with a high metastatic rate.

• Peripheral nerve sheath tumor: a group of neural tumors arising from Schwann cells or perineural fibroblasts (or both) of the cranial nerves, spinal nerve roots, or peripheral nerves; may be classified as histologically benign or malignant.

• Peripheral odontogenic fibroma: a benign mesenchymal odontogenic tumor associated with the gingiva and believed to originate from the periodontal ligament; characterized by varying amounts of inactive-looking odontogenic epithelium embedded in a mature, fibrous stroma, which may undergo osseous metaplasia; historically has been referred to as fibromatous epulis or, when bone or toothlike hard tissue is present within the lesion, ossifying epulis.

• Plasma cell tumor: a proliferation of plasma cells, commonly occurring on the gingiva or dorsum of the tongue; also called plasmacytoma.

• Squamous cell carcinoma: an invasive, malignant epithelial neoplasm of the oral epithelium with varying degrees of squamous differentiation; the distinction between tonsillar and nontonsillar has been made, with the former having a higher metastatic rate and being associated with a poorer prognosis.

Treatment options

Once a mass is noted, treatment planning involves making a definitive diagnosis through cytology or histopathology and removal, if possible and practical. Close excision is usually curative for benign masses. For malignant masses without apparent metastasis, after staging, wide excision with at least 2-cm clean margins is the goal (Figure 5). If the client is willing, the excision can be accomplished in a single procedure. Alternatively, two procedures can be performed: a biopsy to confirm malignant diagnosis followed by complete excision with margins, if possible.

Figure 5A. Oral mass in a 10-year-old golden retriever. Cytology at the time of initial anesthesia indicated malignancy, which was later confirmed by histopathology as fibrosarcoma. (Figure 5B.)

Figure 5B. Wide excision with at least 2-cm margins confirmed on histology.

Figure 5C. The patient 1 year later.

Multiple surgical and radiation options are available to treat neoplasia. Surgical options include intracapsular, marginal, or en bloc excision as well as radical resection. Intracapsular excision removes the tumor from inside the capsule to treat well-differentiated odontomas, which can be curetted from the maxilla or mandible.

Marginal excision removes the lesion visually but may be poorly suited for lesions that are not well demarcated from surrounding healthy tissues. This treatment option may leave remnants of the tumor in place, resulting in regrowth.

En bloc excision removes the tumor, pseudocapsule, reactive zone, and a narrow margin of normal tissue. It is indicated for the treatment of malignant and infiltrating tumors that are not known to extend deep into surrounding tissues.

Radical resection, in which large portions of the maxilla and/or mandible are removed, is indicated for the treatment of aggressive benign and malignant tumors that invade the mandible or maxilla or involve the tongue, resulting in removal in most of the tongue.

Radiation therapy is employed with curative intent for localized tumors with incomplete margins after surgery. Alternatively, radiation can be used to downstage oral tumors before surgery. Response rates are best for squamous cell carcinoma, with more moderate responses expected for fibrosarcomas and malignant melanomas.

Anesthesia in the geriatric dental patient

Anesthesia safety is a primary concern in every patient, but seniors have special needs when it comes to anesthesia. Old age is not a contraindication to general anesthesia, but it can increase the relative risk of the procedure compared with anesthesia in younger patients.

Anatomic and physiologic concerns

Age-related cardiac anatomic changes include myocardial fibrosis; myxomatous valvular degeneration, potentially leading to valvular incompetence; and ventricular wall hypertrophy. Older patients have reduced cardiac reserve and a decreased ability to compensate for anesthesia and hypoxia. Medications that increase the risk for arrhythmias (e.g. α2-adrenergic agonists such as xylazine and medetomidine) and high doses of ketamine should be used with caution. The maximal heart rate response during physiologic stress is reduced in an aging heart due to β-receptor attrition and reduced receptor affinity. An increase in vagal tone and a reduction in blood volume are also seen.

Older patients also have reduced respiratory reserve, which becomes particularly important when combined with the depressant effects of opioids and anesthetic agents. It is, therefore, important to preoxygenate a geriatric patient for at least 5 minutes.

Anesthetic medications that are dependent on renal excretion (e.g. ketamine) may have a longer half-life in geriatric patients, so they should be used cautiously and conservatively, with medication dose and frequency altered accordingly.

As a result of its α1-adrenergic receptor blockade, acepromazine can produce vasodilation and exacerbate hypotension, particularly when used in combination with other anesthetic medications that also cause vasodilation. Although generally it is best to avoid acepromazine use in geriatric patients, microdoses can be useful in very anxious dogs when an opioid alone has not provided the required sedation. Acepromazine is a poor and unreliable sedative in cats.

Propofol and alfaxalone are potent vasodilators, and profound hypotension may result from their use, especially if the infusion rate is too rapid. A 20% to 40% reduction in blood pressure can be expected with induction doses.

The ketamine/benzodiazepine combination for anesthesia induction can provide good cardiovascular stability, with patients generally maintaining good blood pressure due to stimulation of the sympathetic nervous system and catecholamine release. Ketamine's effects on the cardiovascular system include increases in cardiac output, heart rate, systemic blood pressure, pulmonary arterial pressure and central venous pressure. With its significantly shorter half-life, midazolam is a much better choice than diazepam.

Table: Anesthetic dosing in geriatric dentistry

Drug

Dose

Acepromazine

Dogs: 0.01-0.02 mg/kg SC; 0.005-0.01 mg/kg IV

Cats: Not an effective sedative

Midazolam

Dogs: 0.1-0.5 mg/kg SC, IV for induction

Cats: 0.1-0.2 mg/kg SC, IV

Diazepam

Dogs: 0.1-0.5 mg/kg SC, IV for induction

Cats: 0.1-0.2 mg/kg SC, IV

Ketamine

Dogs: -

Cats: 2-5 mg/kg SC for sedation; 1-2 mg/kg IV for sedation

Butorphanol

Dogs: 0.1-0.2 mg/kg SC

Cats: 0.1-0.2 mg/kg SC

Hydromorphone

Dogs: 0.1-0.2 mg/kg SC

Cats: 0.1-0.2 mg/kg SC

Buprenorphine

Dogs: 0.01-0.03 mg/kg SC

Cats: 0.01-0.02 mg/kg SC

Fentanyl

4-10 µg/kg/hr constant-rate infusion. Capnography is essential, as respiratory depression is likely with the higher doses.

Dogs: 2-5 µg/kg IV

Cats: 2-5 µg/kg IV

Propofol

0.5 mg/kg IV incremental doses to effect for induction; up to 4-8 mg/kg total dose. Use caution; best to combine with fentanyl and midazolam as this will substantially reduce the required dose of propofol and thus the potential for hypotension.

Alfaxalone

Dogs: 0.25 mg/kg IV given in incremental doses to effect for induction; up to 1-5 mg/kg total dose

Cats: 0.5 mg/kg IV given in incremental doses to effect for induction; up to 3-5 mg/kg total dose

Ketamine/ benzodiazepine

Mix 0.5 mg/kg of midazolam or diazepam in a syringe with ketamine at 1-5 mg/kg, then administer IV to effect for induction.

IV = intravenously; SC = subcutaneously.

Potential problems during anesthesia

Aggressive fluid therapy and fluid overload should be avoided in geriatric patients. In addition, older patients are highly susceptible to hypothermia. Placing the animal in a warm environment (e.g. with radiant energy and forced warm air blankets) from the time of premedication can help minimize heat loss. Shivering, which can increase oxygen requirements two- or threefold, increases the patient's vulnerability to hypoxia, particularly during recovery if oxygen demands are not met.

Patient monitoring

The American College of Veterinary Anesthesia and Analgesia recommends that the minimum monitoring for all anesthetized small animal patients include blood pressure, blood oxygen saturation (Spo2), end-tidal carbon dioxide and electrocardiography. Capnography is a noninvasive method to assess the adequacy of ventilation.

Hypotension is common in patients under general anesthesia. If decreased mean arterial pressure persists, turn down the vaporizer to decrease the inhalational agent to a minimum; the addition of an opioid may help. If the patient is hypotensive and bradycardic, treat the bradycardia with an anticholinergic agent first (e.g. atropine or glycopyrrolate).

Immediately after anesthesia, ensure that the animal can maintain adequate Spo2 (≥95%) on room air before discontinuing oxygen therapy. Pulse oximetry should also be utilized in a heavily sedated patient to evaluate the need for oxygen therapy (Figure 6).

Figure 6A. Electrocardiographic monitor clipped on a patient monitors heart rhythm postoperatively. Note the atrial premature beat, which is common in recovering patients.

Figure 6B. Monitor showing normal blood oxygen saturation and respiratory waveforms.

Conclusion

Although they can be extensive, dental problems in geriatric dogs and cats can be corrected safely, with very positive outcomes. General anesthesia in senior dogs and cats is considered safe as long as the patient is examined beforehand, anesthesia and temperature control are tailored to the clinical exam findings and the patient is monitored carefully. 

Dr. Jan Bellows owns All Pets Dental in Weston, Florida. He is a diplomate of the American Veterinary Dental College and the American Board of Veterinary Practitioners. He can be reached at dentalvet@aol.com.