Dr. Patrik Holmboe, head veterinarian at Cooper Pet Care, is blunt about it: cleaning food-stuffed toys "is important, especially if food is placed inside them (such as KONGs)" — because a damp, uncleaned toy is exactly the environment mould and bacteria need, and the fix isn't avoiding food-based enrichment, it's building a proper wash-and-dry habit around it.
It's the kind of thing that doesn't come up until an owner notices something growing where the peanut butter or kibble paste used to be — and then goes looking for an explanation.
Key Takeaways
- Dr. Patrik Holmboe (Cooper Pet Care): food-stuffed toys "get very disgusting if the food is left to rot" — and that's exactly the environment mould needs.
- His standard is simple: treat a food-stuffed toy like a food dish, not an ordinary toy.
- Mould needs moisture, organic material and time — a food-stuffed toy provides the first two by design.
- Seams, fabric layers and internal cavities are the usual hiding spots for residue.
- Washing after each use, and drying fully before reuse, meaningfully reduces the risk.
- Solid, non-porous, seamless materials simply have fewer places for residue to accumulate.
"They get very disgusting if the food is left to rot" — a vet's blunt take
Dr. Patrik Holmboe, head veterinarian at Cooper Pet Care, doesn't mince words about food-stuffed toys: "Cleaning toys is important, especially if food is placed inside them (such as KONGs). They get very disgusting if the food is left to rot, and that certainly isn't something you want your dog's mouth around!" (Great Pet Care)
His suggested standard is simple: "Treating the toy like a food dish usually works wonders." Wash it as often and as thoroughly as you'd wash a bowl — not just when it looks obviously dirty.
Why food-stuffed toys can grow mould in the first place
Mould needs three things to establish itself: moisture, organic material, and time. A toy stuffed with peanut butter, wet food or a kibble paste checks the first two boxes by design — that's the whole point of the toy. The third variable, time, is where the actual risk comes from: a toy that isn't washed and properly dried between uses — especially one with a fabric layer, a seam, or an internal cavity that never fully dries out — gives mould exactly the conditions it needs.
For a full sanitise, Holmboe recommends boiling: "the boiling water will seep into everywhere it needs to go, and give a thorough killing of bacteria and other germs." Most households won't boil a toy after every single session, and they don't need to — but it's a useful reminder of why a quick rinse alone often isn't enough for anything with a seam, cavity or fabric layer where residue can hide.
Where residue actually hides
Some toy constructions make this much easier to avoid than others:
- Fabric or stitched-seam toys — thread and fabric fibres hold moisture long after the surface looks dry.
- Multi-piece or hollow-cavity designs — hard to see inside, and harder to dry out fully.
- Rope elements — fibres can trap moisture between strands even when the outside feels dry.
None of this means these toys are unsafe to use — it just means they need a more deliberate cleaning routine than a quick wipe-down.
What actually helps
- Treat it like a food dish — Holmboe's standard: wash food-stuffed toys after each use, not just when they start to look dirty.
- Let toys air-dry completely before refilling or putting them away — a damp toy sitting in a toy box is exactly the environment mould needs.
- Inspect regularly for discolouration, odour or visible growth, and retire anything showing it.
- Favour solid, one-piece, non-porous materials for food-based enrichment where you can — fewer seams and cavities means fewer places for residue to sit unnoticed.
Where this fits into how we build our own toys
It's part of why our chews are a single seamless mould rather than a stitched or multi-piece construction — no interior cavity, no fabric layer, nothing for food residue to sit in unseen. It's also why we call out that our rubber toys are dishwasher safe (top rack) rather than hand-wash-only — a proper wash cycle is a more thorough way to actually clean a toy than a wipe-down, closer to Holmboe's boiling-water standard than a rinse under the tap. That doesn't make hygiene a non-issue — any toy still needs regular washing and a chance to dry out — but it does mean there's less places for residue to hide in the meantime.
A hygiene habit, not a reason to skip enrichment
None of this is a reason to avoid food-based enrichment — it's one of the better enrichment categories available (see our piece on predictability, scheduling and enrichment). It's simply worth building "treat it like a food dish" into the same routine as the enrichment itself.
Frequently Asked Questions
Does this mean stuffed or food-based toys are unsafe?
No — it means any toy holding food and moisture needs regular washing and full drying, the same as a food bowl or water bowl would. Dr. Patrik Holmboe's own standard is to treat a food-stuffed toy like a food dish.
How often should I wash a food-stuffed toy?
After each use is the safest habit, particularly for anything with a seam, fabric layer or hollow cavity where residue can sit unseen.
Are solid rubber toys immune to mould?
No toy is "immune" — but a seamless, non-porous design has far fewer places for residue to accumulate in the first place, and where it's dishwasher-safe, it can be cleaned more thoroughly than a wipe-down.
What are the signs a toy should be retired?
Persistent odour, discolouration, visible growth, or any sign the surface is breaking down — the same general "inspect regularly" habit that applies to any dog toy.
Looking for a chew that's actually easy to keep clean? Our rubber chews use seamless, single-mould construction with no fabric or hollow interior — and they're dishwasher safe, top rack. Shop the Everyday Bone →
Related reading: What Vets Actually Say to Avoid in Dog Chew Toys →
