D
Defibrillation, Electrical
CONTRAINDICATIONS
• Inability to electrically isolate animal from surrounding animals or humans (e.g., in contact with same pool of water/urine/other conductive medium)
EQUIPMENT, ANESTHESIA
• Defibrillator; ideally, combined defibrillator-electrocardiograph to avoid risk of electrical damage to stand-alone ECG machine
PREPARATION: IMPORTANT CHECKPOINTS
• Is it ventricular fibrillation?
○ ECG shows coarse or fine patternless electrical activity with no synchronized activity (no QRS complexes) when ventricular fibrillation is present.
POSSIBLE COMPLICATIONS AND COMMON ERRORS TO AVOID
• Electric shock can be transmitted to bystanders. Note: This complication can cause cardiac arrest in human or animal onlookers. This result is best avoided by ensuring that no one is in contact with the animal or anything the animal is touching before delivering a shock. It is also important to ensure that no indirect contact from urine, saline, or any other fluids that may be trickling from the animal is occurring between the animal and the shoes of surrounding individuals. Shouting “clear” is not enough, since most people do not know what to do in response.
• Defibrillation is too late. The success of defibrillation approaches 100% when it is performed within the first minute of ventricular fibrillation, then decreases by 10%-15% per minute. Defibrillation is the most important treatment when there is ventricular fibrillation, and some have suggested revising the “ABCs” of resuscitation to the “DABCs,” with D for defibrillation.
• Poor application of paddles on animal
○ Paddles must be set widely apart (i.e., one on each side of the thorax); if too close, an electric arc between them can cause severe skin burns and operator injury.
○ Defibrillator gel must be applied between the defibrillator paddles and the animal’s skin. Note: Any facility that owns a defibrillator must also own a tube of defibrillator gel, because alternatives are inadequate: ultrasound gel is contraindicated (nonionic/nonconductive), alcohol is flammable, and bare skin without a coupling agent can be burned by electric arcs.
PROCEDURE
• Rapid clip of hair over the left and right precordia (area of chest overlying the heart): 20 seconds.
• The ECG diagnosis of ventricular fibrillation is confirmed:
○ Alcohol or gel must be present at all points of contact between the ECG wires/clips and the animal (to rule out poor connection artifact/“pseudofibrillation”).
• The paddles are applied to the thorax: paddle marked “Left” or “Apex” is on left hemithorax, and paddle marked “Right” or “Sternum” is on the right.
• All onlookers and assistants must stand back and be neither in direct nor indirect contact with the animal. The only contact point between the animal and the person administering the shock is the paddles.
POSTPROCEDURE
If the rhythm still appears to be ventricular fibrillation, it should be quickly confirmed (check other ECG leads on the monitor, and ensure ECG connection between animal and machine is good); if confirmed, defibrillation is immediately warranted once again at 8 J/kg. Up to 12 J/kg may be administered. When the rhythm is any other than defibrillation, standard cardiopulmonary resuscitation procedures are followed (see p. 1223).
ALTERNATIVES AND THEIR RELATIVE MERITS
• Precordial thump (physical blow to the chest): theoretically delivers physical “equivalent” of electrical shock; unproven value, many potential drawbacks, and never preferred over electrical defibrillation.
• Pharmacologic defibrillation (bretylium, potassium chloride/calcium chloride, etc.): unproven and not known to be widely successful in the clinical setting.
Dental Extraction
OVERVIEW AND GOALS
• Removal of a tooth in a way that ensures complete removal of the root(s) and rapid healing of the dental alveolus and oral soft tissue
EQUIPMENT, ANESTHESIA
• General anesthesia, preemptive pain control, and regional or local anesthesia are utilized as needed.
ANTICIPATED TIME
About 5 minutes for most simple extractions and 20 minutes for most surgical extractions
PREPARATION: IMPORTANT CHECKPOINTS
Dental radiographs: check for the number of roots, their shape, and their structural integrity (root resorption); the condition of the surrounding bone; and the presence or absence of a periodontal ligament with possible root ankylosis.
POSSIBLE COMPLICATIONS AND COMMON ERRORS TO AVOID
• Oronasal fistula: if occurs, should be closed with a mucoperiosteal flap, either at the time the extraction is done or as a delayed surgery if the gingival tissue is so inflamed that its capacity to hold sutures is questionable.
• Root fracture:
○ Most easily prevented by examination of the preoperative radiographs and proper treatment planning. If the root is in advanced stage of resorption, is ankylosed, and has no evidence of periodontal or endodontic infection, it could be left in place for continued resorption.
○ Although the clinician should try to remove as much root material as possible in an animal with root fracture, the risk of damaging surrounding tissue should be weighed against the benefit of finding the last piece of root material.
○ When a root fragment is left in situ, the owner should be informed of that aspect of the surgery, and follow-up radiographs should be included in the treatment plan. The risk of causing an abscess is higher when the root fragment has been mobilized and its blood supply severed during its attempted extraction.
• Jaw fracture: usually the result of a blind attempt at extracting a tooth on the mandible without preoperative dental radiographs and appropriate treatment planning. Small-breed dogs with severe periodontal disease of the first lower molars and cats during extraction of the mandibular canines are the most likely to be at risk for jaw fracture during dental extraction.
PROCEDURE
• Mobilization of the tooth with dental elevators using first-class lever, wheel-and-axle, or wedge types of forces:
○ The tip of the elevator is used circumferentially as a wedge between the root and the bone to stretch the periodontal ligament, or as a wheel and axle with the side of the blade engaged under the enamel bulge mesial or distal to the tooth, to elevate the tooth out of the alveolus.
○ Use light forces over a longer period (at least 10 seconds each time) to break the attachment without fracturing the root.
• Brief digital pressure to help hemostasis, reduce expansion of the alveolar wall caused by the extraction, and approximate the gingival margins
• With a dental bur, buccal cortical bone and alveolar bone is removed to expose the root surface up to half its length.
• Smooth the edge of the alveolar bone with a bone rongeur or rasp; curette and flush debris out of the alveolus.
POSTPROCEDURE
• Antibiotics are used if the animal shows systemic clinical signs (fever, loss of appetite, etc.) or if the condition has progressed to osteomyelitis.
Dental Preventive (Home) Care 
CONTRAINDICATIONS
• When the animal needs professional dental prophylactic treatment (gingivitis, calculus, or plaque buildup) or periodontal treatment (periodontitis, loss of dentogingival attachment)
PREPARATION: IMPORTANT CHECKPOINTS
• The home dental care regimen should be selected after considering the animal’s needs; the will, availability, and dexterity of the owner; and the compliance of the animal.
POSSIBLE COMPLICATIONS AND COMMON ERRORS TO AVOID
• The desire to achieve thorough oral hygiene right at the beginning is often a deterrent for the owner and the animal. Most pets will not tolerate more than 20 seconds of toothbrushing and will not allow brushing the aspect of the teeth facing the palate or the tongue.
• In pets that have minimal calculus buildup, an annual thorough dental examination/cleaning under anesthesia often is not recommended. As a result, these animals may end up having severe dental or periodontal problems for an extended period of time before the problem gets noticed. It is sad that after investing a lot of effort in home dental care for prevention, these owners are not getting the success they were expecting because the recommendation for professional dental care was never made until it was clinically obvious that a problem was present. Pets, just as humans, need both: home dental care and professional dental care.
• Many chew toys have a round cross-sectional shape and are so hard that the carnassial teeth are prone to break when the pet bites down on them.
• There are so many products on the market and so many claims, most unsupported by credible independent research, that it is difficult to choose what to recommend to clients. A credible and independent source of information on the efficacy of dental products is the Veterinary Oral Health Council website (www.vohc.org), and products bearing the council’s seal are recommended.
PROCEDURE
Training for toothbrushing; instructions for the owner:
• As the pet gets used to it, go farther caudally in the mouth until the pet tolerates the procedure being done up to and including the molars.
• Once the pet is comfortable with the procedure, start using a toothbrush with soft bristles, and apply the toothpaste again on the rostral teeth, brushing for a few seconds.
• Go farther caudally as the pet tolerates the procedure. Give praise and rewards immediately after. Brush daily.
• Movement: for the incisors, brush from the gingiva toward the tip of the teeth. For the other teeth, brush with a circulatory movement with the bristles slightly oriented toward the gingiva of the upper jaw, then lower jaw, so that the action is focused on the area next to the gingival margin. With the mouth closed, the last teeth of the lower jaw are hidden behind the teeth of the upper jaw; however, the area next to the gingiva can still be brushed.
• Food specially designed to prevent calculus or plaque formation either mechanically (fibers) or chemically. Fibers help clean the caudal teeth.
• Rinses: chlorhexidine 0.12% for treatment and prevention of gingivitis (not for periodontitis, because it is ineffective on organic material, cannot reach bottom of periodontal pockets); zinc and ascorbic acid, mainly for their action on epithelium and connective tissue post treatment.
Dental Prophylactic Treatment
CONTRAINDICATIONS
• Established periodontitis: animal should receive more involved diagnostic and treatment procedures rather than prophylactic treatment. Diagnosis includes dental examination, periodontal probing and full-mouth intraoral radiographic examination. The first stage of treatment is aimed at controlling the infection; it includes dental cleaning and polishing, root planing, dental extractions and antimicrobials as needed. It is followed by a period of maintenance with home care and reevaluation. The second stage of treatment, periodontal surgery, is done a month later once the periodontium has healed, if the level of compliancy of the owner with home dental care is adequate and if the periodontium still needs to be restored to help prevent reinfection.
EQUIPMENT, ANESTHESIA
• Power instruments:
○ Ultrasonic (magnetostrictive with metal stack, magnetostrictive with ferrite rods, or piezoelectric) or sonic scaler
○ One perio (or universal) tip for removal of subgingival calculus and debris. The energized water spray at the end of the tip also kills bacteria with what is referred to as the cavitation effect.
○ Dental unit, either air or electric powered, with low-speed handpiece and contra-angle attachment. Since the speed of the prophy cup should be around 4000 rpm, a contra-angle-attachment with a 4:1 gear ratio is usually necessary with air-driven units.
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