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Creature Companion 2017; October: 30-31.
Anton C. Beynen
Diet and doggy breath
Bad breath is a common condition in companion dogs and an annoying problem for owners.
Mouth odor is usually caused by bacteria that produce volatile sulfur compounds with offensive
smell. The bacteria can be controlled by regular toothbrushing and professional cleaning, which
improves breath in most cases. Suitable dry foods and treats can further help combat stinky
breath. The marketplace offers products for fresh breath, but their efficacy is usually unknown
beforehand.
To evaluate breath-freshening foods and treats, oral malodor in dogs has to be quantified. Human
perception, by sniffing and scoring of mouth air, represents the real-life situation. Mouth air can
also be examined with a sulfur monitor. The results of sniff and sulfur tests are reasonably
interchangeable as they move in tandem. Worsening bad breath goes hand in hand with
increasing plaque and calculus on the tooth surface and with more severe gum inflammation.
The type of diet and certain dental chews can influence dog breath. Experiments showed that
large-sized kibbles with enhanced teeth contact can improve breath smell. Dogs given chew treats
in addition to their base diet had less offensive breath. The abrasiveness of dental kibbles and
chews brings about mechanical removal of dental plaque. There is no solid evidence that herbal
bacteria killers in dog food contribute to control of oral malodor.
On a scale of 0 to 10, with 0 indicating no noticeable malodor and 10 representing extremely
intensive malodor, an effective dental diet or chew may improve average breath odor by about
one scale unit. The improvement is perceivable by dog owners, but seems small, while many
individual animals will respond below average. Nevertheless, effective dental diets and treats help
freshen breath between toothbrushing.
Halitosis and dental disease
Halitosis can have an oral or non-oral etiology. Hydrogen sulfide and methylmercaptan, produced by
certain bacteria in the oral cavity, are seen as the most common reason for bad breath. Oral
malodor in dogs is quantified by human perception or by measuring breath volatile sulfur
compounds. Sensory assessment is the gold standard as it simulates everyday practice.
Sensory ratings and breath sulfur concentrations are linearly related, but the explained variation is
only about 50% (1, 2). Increasing degrees of dental plaque, calculus and gingivitis are associated with
higher breath scores (3) and sulfur concentrations (4). Dental prophylaxis in dogs reduces breath
sulfur (5), but mechanical removal of plaque by daily toothbrushing has a durable impact (2, 6).
Canine periodontal disease unquestionably leads to halitosis.
Food texture
In a double-blinded, cross-over trial with 7-day periods, 20 dogs were fed a reference dry food or a
veterinary dental diet (7). The dental food consisted of large, abrasive, more fibrous kibbles with
enhanced resistance to crumbling on chewing, thus providing mechanical plaque control. On a 0-10
scale, mean baseline sensory malodor score was 2.6. The dental diet induced a statistically
significant improvement of 0.5 units. When compared with the same reference food, the dental food
has been shown to reduce dental plaque by 19% after one week (8) and by 39% after six months (9).
For four months, dogs were fed one of three diets: the above-mentioned textural kibbles, a canned
food or a mixture (10). Compared with the wet food, the kibbles alone or as inclusion were found to
reduce halitosis. No reference was made to score values and blinding of scoring.
Herbal supplements
Switching from a control diet to the same diet with an extract of green tea leaves diminished breath
sulfur in dogs and cats after 7 weeks (11, 12). There also was a decrease in gingivitis and plaque-
derived Porphyromonas, which produces volatile sulfur compounds. However, the studies lacked
control groups and reported breath sulfur concentrations are improbably high.
In a cross-over experiment with 30-day periods, 32 dogs were fed a dry food without or with herbal
supplement (13). To formulate the test food, chicken meal in a commercial diet was replaced by
6.5% of a complex herb mixture and fish meal. Breath hydrogen sulfide and methylmercaptan were
markedly reduced by the test diet, but the presented concentrations are improbably low.
Probiotic
Mixing Streptococcus salivarius tablets with the morning meal of dogs lowered malodor scores (14).
In oral gas, hydrogen sulfide and methylmercaptan were undetectable throughout. Possibly, the
tablets were swallowed intact and affected extra-oral halitosis.
Dental chews
Addition of different types of dental chews to a dry diet reduced breath sulfur in dogs (6, 15, 16).
Prior to testing, the dogs’ teeth were scaled and polished. There were 17-30 dogs per treatment,
which lasted 4 weeks. Average control sulfur concentrations corresponded with 3.6 on a 0-10
sensory scale (2) while chew-mediated lowering was 1.6 units (Note). In another study (17),
undefined halimeter scores pointed to a smaller chew effect on halitosis.
Feeding a dental chew six days per week has been shown to maintain low breath sulfur for up to 21
months (15). A once-daily chew regimen appears to control oral malodor as it preserved a low, flat
diurnal pattern of breath sulfur (18). All the chews that improved halitosis also reduced
accumulation of dental deposits, just like severity of gingivitis (6, 15-17).
Antimicrobials
Topical (19-22) or pill (5) administration of various antimicrobials reduced halitosis levels in dogs.
Note
Within the range of 2 to 8 (on a 0-10 scale) for organoleptic halitosis scores, a difference in volatile
sulfur compound concentration in dog breath of 1 ppb equals a score change of 0.041 unit as based
on the linear regression line (2). After 4 weeks of feeding a dry diet without or with dental chew, the
group-mean control versus test sulfur concentrations were 125 versus 102 (6), 160 versus 126 (15)
and 128 versus 70 ppb (16). The mean chew effect of 38.3 ppb lowering corresponds with a decrease
of the halitosis score by 1.57 unit (38.3 x 0.041).
Literature
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