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Oral home care in dogs and cats

Dental plaque and periodontal diseases

Periodontal diseases are the most common, usually chronic inflammatory diseases of dogs and cats as they affect majority of the older population of dogs, especially of smaller breeds, and majority of cats. Periodontal diseases are infectious diseases, caused by bacteria in the dental plaque (biofilm on tooth surfaces), which, once mature, is highly organized and hence also resistant to host response and antimicrobials. Plaque is subsequently mineralized to form dental calculus. Plaque-bacteria cause inflammation of the gingiva (gingivitis), which may persist for years, but is completely reversible disease with removal of plaque. However, if gingivitis is left untreated, it causes (mostly) irreversible destruction of the periodontium (periodontitis), and may lead to loss of tooth function and ultimately tooth loss. It has been described, that without oral homecare, periodontitis develops very early in life of some breeds of dogs.

Oral homecare should be instituted early in the life of an animal and continued throughout life with regular professional oral care to ensure periodontal health in pet animals.

Professional oral care

The frequency of visits to the veterinarian to provide professional oral care depends on an individual animal’s disease stage and rate of progression, as well as oral homecare measures provided. In some cases professional oral care may be suggested as often as twice yearly. The purpose of these visits is to determine the severity and extent of periodontal (and any other oral/dental) diseases by means of detailed oral/dental examination and dental radiography and provide an appropriate treatment. Treatment of periodontal diseases always starts with professional dental cleaning that includes supra- and subgingival scaling and polishing to remove dental plaque and calculus. In cases of advanced periodontal disease, periodontal therapy is provided as indicated, where professional dental cleaning is followed by periodontal debridement, root planning, periodontal surgery, extractions and/or any other surgical procedures as indicated. All these procedures can only be accurately performed under general anaesthesia in animals.

Oral homecare measures

Bacteria start to colonize clean enamel surfaces within minutes. Oral homecare is not a substitute for regular professional oral care as it does not remove existing dental deposits, but with proper oral homecare the intervals between professional oral care visits can be extended and hence the total costs of veterinary dental procedures reduced.

The golden standard of oral homecare in animals is still active mechanical removal of plaque by tooth brushing with a soft-bristled toothbrush. In animals, daily tooth brushing is recommended, and it should start when deciduous dentition is still present and should be continued throughout life of an animal. An adequate technique applied for at least 30 to 60 seconds on each side of the mouth should be employed. Without opening the mouth of the animal and just lifting the lips, a tooth brush is placed at a 45° angle to the tooth and circulated over the dental surface with moving the bristles away from the gingiva and sulcus. The easiest is to start with easy-to-reach areas first (upper jaw, rostral teeth, buccal surfaces) and gradually teach the pet to tolerate brushing for extended periods of time and more caudal teeth and lingual/palatal surfaces of the teeth. Tooth brushing is usually easier in dogs and hence more data on the efficacy of daily tooth brushing are available for this species, compared to cats. It is also of an utmost importance to regularly remind and encourage the clients to continue with daily tooth brushing of their pets’ teeth as it has been shown, that only 53% of clients are compliant with oral hygiene recommendations 6 months after professional oral care.

Without oral homecare, the benefits of professional oral care are short-lived.

Tooth brushing may be complemented with the use of a toothpaste. In this case, toothpastes for human use must not be used due to their potential toxicity to animals. Toothpaste may improve animal’s acceptance of tooth brushing, but certain toothpastes alone may reduce the number of oral bacteria in dogs, although they are not as efficient as mechanical removal of bacteria with a toothbrush.

In some animals, tooth brushing is very difficult or impossible, and other oral homecare measures need to be employed, although their efficacy is less than that of tooth brushing. Chewing activity is believed to enable physiologic cleaning of teeth (depending on the chewing habits of the animal). Soft diets are associated with poorer oral/periodontal health. When selecting a diet, treat or a toy that is to be chewed on by the animal, it is also important to consider the size and hardness of it in order to avoid e.g., dental fractures and intestinal blockage. The toy or treat should be flexible enough that can be bent, and soft enough that it can be dented with our fingernail.

Several diets, chews and edible treats are commercially available and proven to help with oral homecare in pets by their mechanical and/or chemical action on plaque and/or calculus. In general, mechanical action of a diet/chew/treat is attributable to its’ textural characteristics (size, shape and consistency) that allows for maximal contact with the teeth. Chemical action of a diet/chew/treat comes from added different chemotherapeutics - e.g., chlorhexidine, or polyphosphates (usually added as coatings to help inhibit new dental calculus formation by binding salivary calcium, with limited success). Chews and edible treats are usually used daily, hence their amount should be limited and their calories counted towards the daily requirements of the animal. There are several different dental chews available, where daily addition to a dry diet regimen was proven to be effective in reducing plaque and/or calculus and/or oral malodour and/or gingival indices in dogs. Daily addition of certain chews has also been shown to have an added oral health benefit when tooth brushing was performed every other day.

The efficacy of oral rinses, sprays, gels, water additives and wipes for teeth to reduce plaque and calculus accumulation is mostly attributable to chemical action of the ingredients, which may vary. The most commonly used chemical agent is still chlorhexidine. Chlorhexidine gluconate form is preferred form to be used in the oral cavity. It is a non-specific antimicrobial agent with a broad antimicrobial spectrum and anti-plaque activity, but due to its specific mechanism of action it does not promote bacterial resistance. Chlorhexidine exhibits substantivity and twice daily application is recommended. In animals it is usually used as a 0.12% solution, but dilution to 0.05% minimizes risk of tissue irritation. Chlorhexidine is widely used peri-operatively and in the immediate post-operative period, while data on its long-term use in animals are rare. Zinc ascorbate used after professional dental cleaning has also been described in cats as an effective anti-plaque agent that also reduces gingivitis. Drinking water treated with xylitol each day was found effective in reducing plaque and calculus accumulation in cats. Xylitol, however, should be used with caution, particularly in dogs, as it can cause liver failure. Several other formulations/active ingredients (e.g., cetylpyridinium chloride, enzyme systems, essential oils, herbal compounds, probiotics) are available and some regularly used by humans. However, it is prudent to check for safety of such ingredients for animal use and scientific data supporting their efficacy in maintenance of periodontal health prior to recommending such products to the clients.

Dental sealants applied immediately after professional dental cleaning act as physical barriers for accumulation of bacteria. They have been shown to be safe and to reduce plaque and calculus accumulation in dogs and cats, but the effect on gingival indices varied or lacked in these studies.

If you have noted any problems with your animal, please consult your veterinarian.

Although every anaesthetic and surgical procedures carries certain risks, most can be prevented by performing proper (pre-anaesthetic) examination, using appropriate equipment and techniques and providing careful monitoring.

This article addresses the most common possible perioperative complications in veterinary dentistry patients and what to do to prevent them.

Complications related to local anaesthesia

Nerve blocks are commonly used in animals undergoing oral/dental procedures as a part of multimodal approach to analgesia/anaesthesia. Administration of nerve blocks has been shown to help reduce the amount of general anaesthetic used and the postoperative pain.

Careful technique and appropriate maximum dosage/volume of the local anaesthetic used are of the utmost importance to avoid complications.
Nerve blocks may be associated with systemic toxicity of the local anaesthetic, including life-threatening neurotoxicity and cardiotoxicity. Accidental direct intravascular injection and/or excessive dose of local anaesthetic is the most common mechanism for production of excess plasma concentrations of local anaesthetics and their adverse effects. Hence maximum total dose (in milligrams) must be calculated and aspiration must be performed prior to injection. Local anaesthetics can also be locally toxic causing nerve damage if injected intrafascicularly or deposited within the nerve as the needle is withdrawn. As nerve damage may possibly be related to mechanical trauma of the needle, gentle technique and use of fine needles (27G) with short bevel, which is oriented in the same direction as the nerve fibers, is recommended. Local anaesthetic should not be injected if resistance to injection is encountered, which likely indicates nerve penetration - in such case, gentle repositioning of the needle, aspiration and application should be performed. If hematoma occurs at the site of injection, it usually resolves without complications.
Infections associated with nerve blocks appear to be extremely rare, however, aseptic technique is recommended especially when using extraoral approaches, and disinfection of the oral cavity (with e.g., 0.12 % chlorhexidine) is recommended prior to any oral/dental procedure.
With inferior alveolar nerve block one needs to be aware of the possibility to block the lingual and mylohyoid nerves, if the local anaesthetic is deposited too far away from the mandibular foramen, which may result in (temporary) desensitization of the tongue and related tongue chewing post-operatively.
Maxillary nerve block was associated with a globe penetration and subsequent need for eye enucleation in cats, hence the knowledge of the anatomy of the maxilla careful nerve block technique (infraorbital nerve block is considered preferable) are of an utmost importance.

Complications related to general anaesthesia

General anaesthesia is required for all dental procedures. It has been reported, that, overall, cats have a higher risk of complications from anaesthesia compared to dogs. Reported risk factors included higher ASA grade, old age, extremes of body weight, urgency of procedure, endotracheal intubation and intravenous fluid therapy.

The risks of general anaesthesia can be significantly reduced with meticulous pre-anaesthetic examination and preparation of the patient, good anaesthesia planning, monitoring of the life functions during anaesthesia.

Monitoring is ideally done by an experienced anaesthetist and involving monitoring of at least body temperature, blood pressure, capnography, pulse oximetry), and close observation of the patient during the recovery period.

Hypothermia is a common problem during anaesthesia (mostly in cats, small dogs and other small mammals), especially with long dental procedures. It is expected even more so in geriatric patients with underlying diseases. Hypothermia can affect function of several body systems and hence impair anaesthesia and general recovery, or even lead to peri- and post-operative complications. Body heat is dissipated with evaporation, conduction, convection and radiation – most important ways are through the anaesthetic system (especially non-rebreathing systems) and cold anaesthetic gases, by large amounts of water used in the oral cavity and cool surgical tables/rooms. Other than shivering, the most common complications associated with hypothermia are a threefold increase in morbid myocardial events, a threefold increase in the risk of surgical wound infection, and an increase in blood loss. Adverse cardiovascular events can follow perianesthetic depression of cardiac output and heart rate, which typically do not respond to parasympatholytic administration, when consequence of hypothermia. Hypothermia during the postoperative period markedly impairs thermal comfort, and physiologic stress leads to increases in heart rate, blood pressure, and oxygen consumption. Hypothermia most likely contributes to wound infection through impairment of immune function and through thermoregulatory vasoconstriction, which, in turn, diminishes oxygen delivery to surgical sites. Even mild hypothermia impairs blood clotting. Drug metabolism can be markedly decreased by hypothermia. During intravenous infusion of propofol, plasma concentration is increased by 30% in patients who are 3°C hypothermic. The pharmacodynamics and pharmacokinetics of volatile anesthetics are likewise altered. Minimum alveolar concentration (MAC) is reduced by 5% for each °C below normal.

Therefore, it is very important to prevent hypothermia from occurring as much as possible by close monitoring of the patient’s body temperature throughout the procedure (every 5-10 minutes) and after the procedure until the patient is normothermic, and provide adequate thermoregulatory support.

To avoid any long-term detrimental effects, body temperature should be maintained above 35.5°C. Special attention should also be paid on not to overheat a patient and carefully using certain heating devices not to cause burns. Wet animals in particular, are at risk of burns as wet surfaces transfer heat more readily. Direct contact with heating pad must be avoided. As an anaesthetised animal is unable to change position in response to excessive heat, anaesthesia staff must monitor the animal regularly, inspecting the surface of the animal for any signs of increased heat.

Aspiration of liquids from the oral cavity is possible, especially if animals are placed in dorsal recumbency. Hence, airway protection is needed and the animals should be endotracheally intubated, pharynx gently packed with absorbent pack (e.g., gauzes) that is changed during the procedure (and removed at the end of the procedure!) when saturated with fluid, and aspiration used at all times. Note that sublingual edema may result from pharyngeal pack packed too tightly.

Tracheal rupture has been reported to occur in cats during anaesthesia, commonly related to dental procedures, although the cause has remained undetermined. To prevent tracheal damage, head and neck should be carefully manipulated during dental procedure and endotracheal tube disconnected from the breathing system any time when changing patient’s or tube’s position. If using the stylet during intubation, special care should be employed. Endotracheal tube cuff must be carefully inflated, as its’ overinflation has been considered the most likely cause of tracheal rupture with ruptures being of a greater length when high-volume low-pressure cuff was used. The cuff should be carefully inflated also to avoid pressure on the mucosal blood flow in the trachea. After initial light inflation of the cuff, a test can be performed to evaluate the effectiveness of the seal by manually delivering a positive pressure breath up to 15-20 cm of water and listening for escaping gas around the cuff. If a leak is detected, the cuff can be inflated further until a seal is maintained. The cuff must be deflated before extubation.

Corneal damage can be a result of physical trauma or decreased production of tears during anaesthesia (especially if using medetomidine/ketamine and volatile agents). Eyes should be lubricated and protected from the physical trauma (cover surgical field) in order to avoid corneal damage and ulceration. Lubricant should be applied every 30 minutes throughout anaesthesia and recovery period.

If you have noted any problems with your animal, please consult your veterinarian.