Chew on This: Dentistry and Nutrition: Dental Disease and Diet; The Nutritionist View
Dry vs. Moist Pet Foods
A common perception in small animal practice is that feeding dry pet foods decreases plaque and calculus compared to canned foods. Biting into a hard kibble would seem to clean the teeth; actually, moist foods may have similar effects to typical dry foods on dental health. As the pet bites into a typical kibble, it shatters and crumbles, providing little mechanical cleaning. In one study, dogs and cats eating soft foods did have more plaque and gingivitis than those eating a more fibrous food1 and there was a significant benefit of feeding commercial dog and cat foods compared to homemade foods when at least part of the diet was a dry petfood2. Feeding homemade foods vs. commercial wet and/or dry foods showed that feeding a homemade diet increased the probability of oral health problems in cats.2 Another study also shows an improvement in periodontal disease, tartar, and decreased lymphadenopathy in cats fed dry food compared to soft or homemade food.3 In other studies, moist foods have shown a similar effect to typical dry foods on plaque and calculus accumulation.4,5
Dental Diets and Treats
Some foods and treats for dental cleaning have a texture which maximizes the contact with the teeth. Foods with the right shape, size, and physical structure can provide plaque, stain, and calculus control. A 6-month study comparing feeding a dental diet to a typical maintenance diet showed about a third less plaque and gingival inflammation with the dental diet. A dental diet fed to Beagles significantly decreased pre-existing plaque, calculus, and gingivitis, whereas these increased on a maintenance diet.6 The type of fibre in dental diets is thought to exercise gums, promote gingival keratinization, and clean teeth. Dental treats need to be very hard, and can sometimes fracture teeth.
Some diets and treats contain antibiotics or additives to retard or inhibit plaque or calculus, e.g., sodium hexametaphosphate (HMP) which forms soluble complexes with calcium and decreases the amount available for forming calculus. Adding HMP to a dry diet decreased calculus in dogs by nearly 80%7 although another study showed no difference in plaque or calculus when HMP-coated biscuits were fed to dogs for 3 weeks.8
Veterinary Oral Health Council (VOHC)
A way to check if a food or treat prevents or decreases plaque or calculus is its approval by the VOHC (vohc. org). The VOHC is a non-regulatory agency which includes representatives from professional dental associations, AVMA, AAHA, FDA, private practice, and industry. The VOHC provides independent and objective reviews of tests of dental products submitted in accordance with their protocols, although they do not provide testing themselves. The VOHC awards a seal of acceptance for two categories: helps control plaque and helps control tartar.
Deficiencies in vitamin A, C, D, and E, and the B vitamins, folic acid, niacin, pantothenic acid, and riboflavin have been associated with gingival disease. These are adequate in diets which meet AAFCO or FEDIAF guidelines but can be deficient in other diets, such as many homemade diets.
Natural Diets and Feeding Raw Bones
Proponents of natural foods or feeding raw bones have claimed improvement in cleanliness of pet’s teeth; further claims are sometimes made that feeding commercial petfood contributes to the high prevalence of periodontal disease. However, a study in Foxhounds fed raw carcasses, including raw bones, showed that they had varying degrees of periodontal disease as well as a high prevalence of tooth fractures.9 The skulls of 29 African wild dogs eating a “natural diet”, mostly wild antelope, showed evidence of periodontal disease (41%), teeth wearing (83%), and fractured teeth (48%).10
Small feral cats on Marion Island (South Africa) eating a variety of natural foods (mostly birds) showed periodontal disease in 61%, although only 9% had evidence of calculus11 Australian feral cats eating a mixed natural diet had less calculus compared to domestic cats fed dry or canned commercial food, although again there was no difference in the prevalence of periodontal disease.1,2 These studies show that a diet containing raw bones does appear to confer some protection against dental calculus, but not against the more destructive periodontal disease. There is also the risk of fractured teeth.
Nitric oxide (NO), an important inflammatory mediator, is increased in human periodontitis and agents blocking the production of NO or its effects might be therapeutically valuable. Lactobacillus brevis (L brevis), is a probiotic bacteria which contains high levels of arginine deiminase (AD). High levels of AD inhibit NO generation by competing with NO synthase for the arginine substrate. In humans topical application of probiotics containing L brevis decreased inflammatory mediators involved in periodontitis. Preliminary results of topical L brevis CD2 in dogs showed reduced of gingival inflammatory infiltrates.13
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3. Gawor JP, Reiter AM, Jodkowska K, et al. Influence of diet on oral health in cats and dogs. J Nutr. 2006;136:2021S–2023S.
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7. Stookey GK, Warrick JM, Miller LL. Sodium hexametaphosphate reduces calculus formation in dogs. Am J Vet Res. 1995;56:913–918.
8. Logan EI, Wiggs RB, Schert D, Cleland P. Periodontal disease. In: Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ, eds. Small Animal Clinical Nutrition, 5th ed. Topeka, KS; Mark Morris Institut; 2010:989–1001.
9. Robinson JGA, Gorrell C. The oral status of a pack of foxhounds led a “natural” diet. In: Proceedings of the World Veterinary Dental Congress. Birmingham, UK: 1997:35–37.
10. Steenkamp G, Gorrell C. Oral and dental conditions in adult African wild dog skulls: a preliminary result. J Vet Dent. 1999;16(2):913–918.
11. Verstraete FJ, van Aarde RJ, Nieuwoudt BA, et al. The dental pathology of feral cats on Marion Island; part II: periodontitis, external odontoclastic resorption lesions and mandibular thickening. J Comp Pathol. 1996;115(3):283–297.
12. Clarke DR, Cameron A. Relationship between diet, dental calculus and periodontal disease in domestic and feral cats in Australia. Australian Vet J. 1996;76(10):690–693.
13. Vullo C. Lactobacillus brevis CD2 and odontostomatological diseases. Probiotics in veterinary medicine - an update and perspectives. The Sivoy Study. The Sivoy Study Group. Rome 17 March 2014, Abstract.