Why insect-based dog food reduces bad breath in dogs

Nutrition & oral health

Most cases of bad breath in dogs come down to one place: the mouth. The bacteria that build up in dental plaque break down protein fragments and produce volatile sulphur compounds (the gases responsible for the smell and, over time, for gum tissue damage). A 2024 study in the Journal of Insects as Food and Feed found that dogs switched to black soldier fly larvae kibble had measurably fewer of those bacteria in their plaque and more beneficial species in their saliva.^[1] The protein source, it turns out, matters more than most people expect.

The root cause of bad breath in dogs

The source of the smell is bacterial, and it's localised to the mouth. Gram-negative proteolytic bacteria colonise dental plaque and digest proteins, amino acids, and components from oral fluids. What they produce in the process are volatile sulphur compounds (VSCs): principally hydrogen sulphide, methyl mercaptan, and dimethyl sulphide.^[2] Those are the compounds you smell. Chronically elevated, they're also associated with progressive periodontal tissue damage.

In a 32-dog study that measured VSCs with portable gas chromatography, hydrogen sulphide concentrations reached 0.43 ng/ml and methyl mercaptan 0.30 ng/ml in affected dogs before any intervention.^[2] These aren't vague impressions. They're measurable, which means dietary changes can be tracked against them.

Periodontal disease, driven by the same bacterial accumulation, was found to affect 86.3% of adult dogs across 42 breeds in a cross-sectional study of US commercial breeding facilities.^[3] So this isn't an edge case for dogs with notably bad breath. It describes almost every adult dog.

Why protein source shapes the oral microbiome

The bacteria producing those sulphur compounds are proteolytic. They feed on protein residues in plaque and saliva. Which means the protein composition of your dog's food influences the oral environment directly, not just what ends up in their gut.

Black soldier fly larvae (Hermetia illucens, BSFL) have an unusual fatty acid profile. Around 40% of their total fatty acids are lauric acid (C12:0). For comparison: chicken comes in at about 1.80%, beef at 0.07%.^[4] Lauric acid is a medium-chain fatty acid with documented antimicrobial activity against E. coli, Salmonella sp., and Clostridium perfringens, among others.^[4]

What the 2024 study found

Eight female beagles. Two iso-nutritive extruded kibble diets, one with poultry by-product meal as the main protein and one with defatted BSFL meal. Each diet lasted 50 days in a crossover design. Researchers measured colony-forming units of volatile-sulphur-producing bacteria in dental plaque, ran bacterial DNA profiling from saliva samples, and scored oral malodour directly.^[1]

Dogs on the insect-based kibble had fewer sulphur-producing bacteria in their plaque. Their saliva microbiota also showed an increase in Moraxella, a genus associated with healthier oral conditions, relative to the poultry-based feeding period.^[1]

Protein quality: insect protein holds up nutritionally

One fair objection to novel protein sources is whether they actually deliver nutritionally. In a study comparing BSFL-based and poultry meal-based diets in dogs, apparent protein digestibility came in at 82.3% for the insect-based diet versus 80.5% for poultry meal. Fat digestibility: 94.5% versus 91.6%.^[4] It holds up. You're not trading nutrition for the antimicrobial lipid profile.

What this means in practice

Bad breath in dogs is a bacterial problem, not a grooming one. Bacteria respond to their environment. The fatty acid profile of whatever protein your dog eats shapes that environment. A protein source with a high lauric acid concentration shifts the microbial balance in the mouth toward fewer sulphur producers.

The BSFL study ran 50 days and found measurable changes in both plaque bacterial counts and saliva microbiota. That's a real shift in what's growing in your dog's mouth, traceable to a single variable: what they were fed.