Though the eyes may be the window to the soul, the oral cavity is one of the first portals to systemic health and welfare for pet dogs and cats.
Why is dental health so important for small animals?
Periodontal disease is defined by the World Small Animal Veterinary Association (WSAVA) as gingivitis and periodontitis (Niemiec et al., 2020). These conditions can be aesthetically unpleasant to pet owners if there is visible calculus and noticeable odour, but the negative impacts go much further than this. And despite the serious health and welfare implications, dental disease has a very high incidence, being one of the most commonly diagnosed disorders of dogs and cats in the UK.
Risk of systemic diseases
Periodontal disease is suspected of increasing the risk of several systemic diseases, including cardiovascular disease, hepatopathy and haematopoietic disorders (Penlington and Faixová, 2019; Bellows et al., 2019). In one study, dogs with periodontal disease were 17 times more likely to have concurrent mitral valve disease (Penlington and Faixová, 2019). In another study, moderate to severe dental disease was a risk factor for developing chronic kidney disease in cats, even after correcting for age (Finch et al., 2016).
Thus, while a causative link between oral cavity health and systemic health is complex and poorly defined, it is hypothesised that increased levels of chronic systemic inflammation may be responsible for a higher incidence of other comorbidities (Bellows et al., 2019).
How does dental disease impact animal welfare?
Among several commonly diagnosed disorders in dogs, dental disease was determined to have the highest overall impact on welfare, due to its high prevalence, the duration of the condition and the severity level in the studied population (Summers et al., 2019). Furthermore, the WSAVA recognises dental and periodontal disease as significant welfare concerns.
It is well known that dental disease can cause significant pain in people, and while it is more difficult to measure objectively in non-human animals, it is generally reasonable to assume that similar levels of pain occur in dogs and cats as a result of periodontal disease.
It is important to dispel the commonly held myth that if pets are eating normally or chewing on toys, they are not experiencing dental pain
Pain-related behaviours can vary greatly between species and individuals, but may include pawing at or rubbing the mouth, hypersalivation, withdrawal from social interaction, a decrease in grooming, a change in food preference to softer foods, bruxism and even aggression.
It is important to dispel the commonly held myth that if pets are eating normally or chewing on toys, they are not experiencing dental pain. While some animals may decrease their food intake or change their food preferences secondary to pain (and in severe cases may not be able to prehend food normally), in most cases, the survival instinct to eat supersedes any behaviour changes caused by chronic pain.
What is the pathophysiology of periodontal disease?
Periodontal disease is chronic and progressive, and it happens in steps, making it difficult for owners to appreciate the disease until it becomes severe.
Regular dental care is important to prevent further progression to inflammatory periodontal diseases like gingivitis and periodontitis
First, bacteria in the mouth mix with saliva to form invisible plaque on the teeth above and below the gum line. If not removed, this plaque mineralises over time into visible calculus. This process can happen in a matter of 24 to 48 hours. However, tartar is much harder to remove than plaque, so regular dental care is important to prevent further progression to inflammatory periodontal diseases like gingivitis and periodontitis.
What should regular dental care involve?
Dental care should include regular veterinary examination of the oral cavity. Bear in mind that absence of visible disease upon routine physical examination in the consult room should not preclude recommendation for a more thorough examination under general anaesthesia. This is because evidence shows that visual examination in conscious animals underdiagnosed dental pathology compared to full-mouth radiographs by 18 percent (Queck et al., 2018).
Because of the rapid ability of plaque and calculus to form, home care in between veterinary procedures is critical to oral health.
Box: The WSAVA Global Dental Guidelines provide a thorough guide to examination under general anaesthesia, including scaling, dental radiographs and polishing as part of the comprehensive procedure.
What should vets recommend to help clients with home dental care?
There are myriad products on the market dedicated to home dental care for dogs and cats. These include dental chews and toys (both digestible and not), treats, rinses, water additives and diets. In addition to commercial products, a wide variety of information about pet dental health can be found by owners both on- and offline, with varying degrees of evidence to support them.
Passive care resulting from chewing and eating behaviours, which requires less effort on the owner’s part, can have a significant impact on dental health in dogs and cats
Active dental home care, such as daily toothbrushing, has been shown to be the most effective strategy to prevent the accumulation of plaque and tartar and the progression to periodontal disease in multiple studies (Allan et al., 2019; Buckley et al., 2011). However, the key to effectiveness is consistency, and, unfortunately, compliance with toothbrushing is reported at only 50 percent for six months, even among motivated owners (Miller and Harvey, 1994). Thus, passive care resulting from chewing and eating behaviours, which requires less effort on the owner’s part, can have a significant impact on dental health in dogs and cats.
Commercial dental products should be evaluated and recommended using an evidence-based approach. The Veterinary Oral Health Council (VOHC) independently evaluates products claiming to have dental benefits and awards their seal for plaque and/or tartar to those with sufficient evidence. (They provide an easily accessible list of approved products online.)
Various nutritional strategies have been recommended to prevent dental disease in dogs and cats.
For many decades, it was thought that extruded dry commercial diets were superior to soft or wet diets. While some studies show increased levels of dental disease among pets on soft foods (Buckley et al., 2011; Gawor et al., 2006), the reality is that many kibbled diets break apart completely on first contact with the teeth, thus do not provide any mechanical dental benefit (Niemiec, 2008).
Information can be found promoting use of various types of homemade or raw meat and bone-based diets and chews (bones, antlers, etc); however, peer-reviewed evidence supporting these claims are lacking. And on the contrary, homemade foods were associated with poorer dental health in one study (Buckley et al., 2011). The WSAVA and American Animal Hospital Association dental guidelines also describe the risks associated with feeding hard items like bones and antlers, including tooth fracture, oesophageal or gastrointestinal foreign bodies and zoonotic diseases (Niemiec et al., 2020; Bellows et al., 2019).
While some studies show increased levels of dental disease among pets on soft foods, the reality is that many kibbled diets break apart completely on first contact with the teeth
Interestingly, in some studies, populations of domestic, wild or feral animals eating raw meat and bone-based diets had less calculus, but showed no reduction in plaque or periodontal disease, indicating that this diet may provide aesthetic cleansing but is not beneficial for preventing more serious periodontal disease (Steenkamp and Gorrel, 1999; Verstraete et al., 1996; Marx et al., 2016).
Softer dental chews present less risk of tooth fracture but are often intended to be consumed daily. Therefore, they can contribute significant additional calories to a pet’s overall intake if this is not accounted for in the rest of the food ration.
Dietetic pet foods
Several veterinary-exclusive dietetic pet foods have been awarded the VOHC seal for plaque and/or tartar. These foods are formulated for the maintenance of adult dogs and cats, and the relatively higher fibre content may also be beneficial for gastrointestinal health and weight management.
The dental and periodontal health of pet dogs and cats is a fundamental aspect of their overall health and welfare. Regular client education, anaesthetised veterinary examination including radiographs, cleaning and polishing, and the promotion of home dental care are necessary to maintain good oral health throughout the lives of pets, especially as they age. Passive home care is an excellent way to achieve consistent client compliance.