Mobile Teeth and a Heart Murmur: Consent for Dental Treatment
A 10-year-old spayed female Yorkshire terrier (3.5 kg, BCS 6/9) presents for halitosis and dropping food. Exam shows grade 3 periodontal disease, mobility of the mandibular incisors and left maxillary fourth premolar, and a grade II/VI left apical systolic murmur. HR 120, RR 24, no syncope or cough. The owner says, 'Just clean the teeth; I don't want any extractions.' Preanesthetic PCV is 42%, TP 7.0 g/dL, BUN 18 mg/dL, creatinine 0.9 mg/dL. The dog is currently on no medications.
1. How should you respond to the owner's request for 'cleaning only'?
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Explain that scaling and polishing alone is not appropriate when teeth are mobile and periodontal pockets are present. Mobility indicates severe attachment loss; cleaning the crowns while leaving infected root surfaces and loose teeth can cause pain, persistent infection, and bacteremia. The standard plan is full-mouth dental radiographs under anesthesia and extraction of teeth that cannot be saved. If the owner refuses extractions, do not perform a routine 'cleaning only' procedure that leaves diseased teeth in place. Offer an examination with radiographs and pain management, document the refusal, and provide an estimate for the recommended treatment. Emphasize the dog's comfort and ability to eat.
2. Outline the preanesthetic and intraoperative plan for this dog, including the murmur.
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The grade II/VI murmur is not automatically a reason to refuse anesthesia, but it should be investigated. Check blood pressure and ECG, and obtain thoracic radiographs and echocardiography if available. Use balanced anesthesia with careful monitoring, IV fluids to support blood pressure, warming, and pulse oximetry/capnography. Perform full-mouth radiographs before extractions, use local anesthetic blocks to reduce intraoperative and postoperative pain, and keep the procedure as short as safely possible. Antibiotics are not automatically indicated for routine dental cleaning; use them if there is evidence of systemic infection or according to the clinician's plan.
3. Calculate the maximum volume of 0.5% bupivacaine for this dog and explain how you would use it for dental blocks.
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The maximum accepted bupivacaine dose in dogs is about 2 mg/kg. For a 3.5-kg dog: 3.5 kg x 2 mg/kg = 7 mg. A 0.5% solution contains 5 mg/mL, so 7 mg / 5 mg/mL = 1.4 mL total. Do not exceed 1.4 mL of 0.5% bupivacaine across all block sites. If a larger volume is needed for multiple sites, use 0.25% (2.5 mg/mL), which gives a maximum of 2.8 mL, but still do not exceed 7 mg total. Aspirate before injecting, use separate syringes for each site, and calculate the total volume for all blocks before starting.