Dogs have an incredibly powerful sense of smell, with around 300 million scent receptors in their noses compared to only 6 million in humans. This allows them to detect odors at concentrations up to 100 million times lower than humans can. But are there any containers that dogs cannot smell inside of?
The Dog’s Sense of Smell
A dog’s sense of smell is its most powerful sense and the main way dogs experience the world around them. The part of a dog’s brain devoted to analyzing smells is about 40 times larger than in humans. Their nasal cavities are also optimized for picking up scents. Air does not go directly to the lungs but to recesses in the nose called turbinates, which contain smell receptors and allow scent particles to accumulate and dissolve in mucus before the air reaches the lungs. Dogs also have a special organ above the roofs of their mouths called the vomeronasal organ that detects pheromones, which carry information about social hierarchy, territorial marking, mood, and reproductive status.
Because of their amazing olfactory abilities, dogs are able to detect smells 10,000 to 100,000 times more acutely than humans. They can pick up scents in parts per trillion and follow odor trails left hours or even days before. Dogs have 220 million olfactory cells in their noses while humans only have 5 million. The average dog’s sense of smell is 10,000 to 100,000 more acute than a human’s. This allows them to detect incredibly faint odors from very small concentrations of molecules. For example, dogs can detect the presence of one drop of blood in five quarts of water, and some dogs can pick out a single rotten apple in a two million barrel stockpile.
Factors That Impact a Dog’s Sense of Smell
While all dogs have excellent sniffers, there are a few factors that impact how well a dog can smell:
- Breed – Some breeds like Bloodhounds are selectively bred for their scenting ability
- Age – Older dogs may experience a deterioration in their sense of smell
- Illness – Certain illnesses and medications may temporarily affect smell
- Injury – Injury to the nose and olfactory system can impair smell
- Obesity – Carrying extra weight can physically inhibit smelling
- Smoking – Exposure to smoke dulls scenting ability
- Weather – Humidity helps odors travel farther, while wind disperses them
Containers Dogs Can Smell Through
Most containers we use in our daily lives are no match for a dog’s nose. Dogs are able to smell through all but the most tightly sealed containers. Here are some containers dogs have no trouble smelling inside:
Plastic, Paper, or Burlap Bags
Food, treats, and other goodies placed in everyday bags will be easily sniffed out by dogs. They can detect any odors escaping through tiny gaps in the material or seams.
Cardboard Boxes
Cardboard provides very little barrier to smell for dogs. They can pick up the faintest whiff of a scent from items stored inside cardboard boxes.
Tupperware
The plastic lids and bodies of Tupperware containers are not enough to disguise smells from dogs. Air remaining inside after closing and odors seeping out around the lid allow dogs to detect contents.
Food Cans and Jars
Sealed aluminum cans and glass jars slow but do not prevent the movement of odor molecules. Dogs can pick out scents escaping through tiny gaps where the lid meets the can or jar.
Backpacks and Purses
Dogs are very adept at rooting out things like food, toys, and medicine hidden away in bags by smell alone. Few bags are truly smell-proof.
Ceramic or Metal Containers
Containers like ceramic cookie jars and metal toolboxes may seem impervious but allow smells to slowly escape over time. Dogs can detect the traces that leak out.
Wax Paper or Plastic Wrap
Wrapping food in materials like wax paper or plastic wrap may keep human noses from detecting odors but does little to hide scents from dogs.
Cloth Sacks or Bags
Burlap, canvas, cotton, burlap, and other types of cloth are very porous materials. Smells easily pass through the weave and reach dogs’ eager noses.
Diaper Pail
Despite being designed to contain stinky materials, most diaper pails cannot prevent the worst odors from escaping. The nose of a dog can pick up hints of smells through the plastic and any small gaps.
Litter Box
A litter box often still allows smells to emanate from both the plastic walls and the litter inside. Dogs can detect trace odors released into the air and locate litter boxes with ease.
Plastic Food Storage Containers
Plastic containers designed for storing human food usually do not seal tightly enough to block odors detectable by canine noses. Dogs can pick up food smells from inside.
Trash Can
Trash cans often have removable lids or bags that leave gaps for smells to escape. Dogs can use these smells to identify tasty morsels buried inside.
Containers That Block Some Smell
While most containers will not completely contain odors from a dog, some materials and designs can make it more difficult for dogs to detect smells. These include:
Vacuum Sealed Bags
Bags designed for vacuum sealing remove more air and seal more tightly than typical plastic bags, slowing odor escape. This may hide some smells from dogs.
Airtight Plastic or Glass
Containers designed to be airtight can block more scent molecules than regular plastic or glass if sealed properly. Look for latching lids.
Scientifically Designed Smell-Proof Bags
Some newer bags have multiple layers of plastic, carbon filters, and air-tight zip seals specially made to contain odors. These may conceal smells from some dogs.
Waterproof Dry Bags
Bags meant to be waterproof for activities like kayaking are often made from materials that also hold in odors better.
Tightly Sealed Coolers
High-end coolers can have very tight rubber gaskets and secure latches able to minimize scent escape. This can make odors harder for dogs to pinpoint.
Sealed Metal Containers
Thick-walled metal boxes with gaskets and air-tight seals can protect against odor leakage. But even a sealed metal box may eventually allow very small amounts of scent molecules to escape.
Containers That Block Most Smell
A few specialized containers can block smells from leaking out even against the nose of a dog. These include:
Activated Carbon
Lined bags, boxes, or cans containing activated carbon absorb odor molecules. This prevents most smells from escaping while sealed.
Nitrogen-Flushed Containers
Some containers flush out air using inert nitrogen gas when sealing. This leaves fewer odor molecules behind for dogs to detect.
Multiple Layer Foil Bags
Bags with several layers of aluminum foil can prevent most odors from escaping through the tiny holes and gaps in the foil.
Smell-Proof Safety Deposit Boxes
Some high-end safety deposit boxes used by banks are designed to be completely smell-proof to prevent dogs from locating contents inside.
Burial Grade Stainless Steel
Very thick stainless steel boxes welded shut can effectively contain smells, but they are heavy, expensive, and rare to find.
Fooling a Dog’s Nose
While containers can make it more difficult for dogs to detect smells, clever dogs may still be able to locate items by scent. Here are some tips that can be used along with smell-proof containers to fool dogs:
- Mask scents with strong smells dogs dislike such as citrus, vinegar, chili powder, menthol, eucalyptus or perfume.
- Place odor absorbers like baking soda, activated charcoal, or coffee grounds inside containers.
- Keep containers in areas with strong ambient odors to disguise smells.
- Store smell-proof containers in hot places as heat speeds up odor molecule dissipation.
- Introduce misleading scents dogs will follow instead of the hidden scent trail.
The Dog Nose Always Wins
When it comes to smelling, dogs will beat out humans every time. Their incredibly sensitive sniffers can detect odors at concentrations up to 100 million times lower than people. While containers can make scents harder to find and disguising techniques may throw dogs off the trail, no containment method is foolproof against the nose of a determined dog.
Dogs can pick up whiffs of smells from incredibly minute amounts escaping even the tightest seals and toughest materials. Given enough time, even containers designed to be smell-proof will likely fail contain odors completely. So if you want to hide something important from a dog, your best bet is simply to place it somewhere the dog cannot access at all!
Conclusion
Dogs have a supernatural sense of smell that allows them to detect odors we cannot perceive. Their powerful sniffers can pick up scents from inside all but the most carefully sealed containers. While many containers we use daily do little to contain odors, vacuum sealing, activated carbon, sturdy metal, and specially designed bags and boxes can make it more difficult for smells to escape. However, even rigorous smell-proofing is hard to guarantee against a determined dog’s nose. The takeaway is that if you really need to hide something from a dog, keeping it completely out of reach is the only sure way to prevent them from sniffing it out.