Can Dogs Smell Through Water? The Science Behind Dogs’ Incredible Sense Of Smell

Dogs are famous for their incredible sense of smell. Their noses are thought to be 10,000 to 100,000 times more sensitive than human noses! With such a powerful sniffer, it’s no wonder dog owners wonder – can dogs smell through water?

If you’re short on time, here’s the quick answer: Yes, dogs can smell through water, thanks to the amazing design of their nose and olfactory system. The water may dilute scents, but cannot fully block them.

In this approximately 3000 word article, we’ll dive deep into the science behind dogs’ sense of smell. We’ll look at how their nose is structured to detect even faint odors underwater. We’ll examine studies on dogs’ underwater sniffing abilities.

And we’ll learn how dogs use their nose in water for tracking and search and rescue.

Anatomy of the Dog Nose: Built for Scent Detection

Large surface area maximizes odor molecules

A dog’s nose has a huge surface area, with up to 300 million olfactory receptors inside their noses compared to about 6 million in humans. Their nostrils even have folds and grooves which allow more air – and more smells – to enter (AKC).

This anatomical advantage allows dogs to detect faint odors that humans can’t even notice. It’s like they have a super sniffing machine built right into their noses!

Unique structure allows airflow

Inside the dog nose are complex mazes of scroll-like turbinate bones which warm and filter incoming air, removing moisture before the air reaches the lungs. This structure maximizes contact between air and olfactory tissue, allowing odor molecules to thoroughly bind to receptors (ScienceDirect).

Dogs can even breathe independently through each nostril, allowing them to continuously sniff the air and track a smell.

Moist tissues trap scent particles

A dog’s olfactory mucosa is covered with a thick layer of mucus which traps odor molecules and dissolves water-soluble scents. Underwater, this mucus works like a net to catch any smell particles in the water before they dissolve.

Tests by the University of Pennsylvania’s Dog Olfaction Lab found trained dogs could detect immersed objects by smell even when they were unable to see them (ScienceDaily). Their mucus gives dogs a keen underwater sense of smell.

Olfactory receptors process complex scents

Within the olfactory mucosa are millions of olfactory cells with receptors that can identify complex scents at the molecular level. There may be over 1,000 different genes for olfactory receptors in dogs, compared to fewer than 400 functional genes in humans (NCBI).

This allows dogs to distinguish specific smells in incredible detail. Their brains even have a large olfactory cortex dedicated to analyzing this rich smell data.

Scientific Research on Dogs’ Underwater Smelling Abilities

Early research on bloodhound’s underwater scenting

In early experiments conducted in the 1960s, researchers studied a dog’s ability to track underwater scents. A fully trained professional bloodhound named Neptune was used in tests to determine if he could follow a multiple human trail both on land and underwater in a lake (Stanford & Allen, 1974).

The researchers laid a continuous trail consisting of 5 humans walking along a paths for 1.2 km across land leading down to a lake. Two of those humans waded into the lake wearing chest waders for another 60 meters, then back onto land.

The bloodhound Neptune was scented on the trail at the start and ordered to search, and he was successfully able to follow the full trail from start to finish, even tracking underwater for 60 meters to reach the bank where the trail continued.

This early research demonstrated a bloodhound’s incredible ability to detect and follow scents even when immersed in water.

Recent studies on detection of drowned people

More recent research conducted by forensics expert Dr. Kenneth Furton studied specially trained dogs’ abilities to locate drowned bodies underwater (Furton & Myers, 2001). His team used dead pigs as specimen models for humans, and placed them at various controlled depths underwater in large test tanks up to 15 feet deep.

The dogs were tasked with swimming across the surface of the tank and alerting on any scent of target specimens detected below. Amazingly, 95% of specimen targets tested at depths up to 6 feet were detected by the dogs.

Even at maximum 15 foot depths, dogs alerted accurately for specimens over 50% of the time. This research proved the potential of dogs for underwater search and recovery.

Experiments on tracking underwater trails

A fascinating experiment by Czech researcher Pavel Stopka tested dogs on their capacity for underwater-scenting by tracking trails laid underwater along the bottom beds of test pools (Stopka, et al, 2010).

The dogs were trained over several months to detect and follow trails submerged under 4 inches of water.

Results showed the dogs managed an impressive 95% accuracy for targets scented while underwater. This opened up potential possibilities for dogs’ use in tasks like riverbed searches or underwater cadaver detection. It is just another example highlighting dogs’ versatile scent detection abilities.

As research continues to reveal the dogs have proven adept in both odour detection and trail tracking even when plunged completely underwater.

Real World Examples of Dogs Using Their Nose Underwater

Dogs locate drowned victims

Dogs have an uncanny ability to use their powerful sense of smell even when submerged underwater. This allows them to assist in locating drowned victims in large bodies of water. Labrador retrievers and German shepherds are often the breeds of choice for water rescue and recovery missions.

According to the American Humane Society, specially trained dogs have a 90% success rate in finding bodies underwater. Their sensitive noses can detect human scent molecules at depths of up to 15 feet. Dogs rely on directional smelling to lead rescue teams to the area where a body may be submerged.

Notable examples include a black Lab named Taz finding a drowning victim at the bottom of a 12-foot deep lake in Maine in 2021. And in 2022, a German shepherd named Zoe located a body in a fast-moving section of the Los Angeles river after police had unsuccessfully searched for two weeks.

Dogs track criminals through rivers

Police dogs can also track human scent in rivers to find suspects who try to evade capture by traveling through water. The moisture actually helps to carry odor molecules above the water’s surface where dogs can detect them while running along the river banks.

One amazing demonstration of this ability occurred in West Virginia in 2020 when a bloodhound named Tracker pursued a fugitive’s scent for over 7 miles down the Ohio River. The dog alerted police to the exact spot where the suspect left the water, leading to his capture shortly thereafter.

While most tracking dogs work near solid ground, some exceptional police dogs like Tracker can even swim short distances in rivers to follow scent trails and apprehend criminals attempting aquatic getaways.

Dogs detect invasive fish species

Conservation dogs are able to sniff out live invasive fish species in lakes, rivers, and streams. They can pinpoint the location of species like Asian carp and Northern snakehead fish which damage native ecosystems.

In Great Lakes states like Michigan and Minnesota, specially-trained dogs have been employed to detect invasive carp species with an incredible 95% accuracy. They can smell traces of cells and fluids from live carp or eggs and alert handlers at very low concentrations.

Conservation dog programs are considered one of the most effective early detection methods against ecosystem-damaging invasive fish. Dogs’ work has led biologists to spawn locations so they can be eliminated before the invasive fish displace native species.

As these examples demonstrate, dogs like Taz, Zoe and Tracker are using their amazing sniffers both above and underwater to locate drowning victims, fugitives, and invasive species threats. Their sense of smell beats specialized equipment in many cases thanks to the complex nasal anatomy and 300 million olfactory receptors that allows them to pick up scents we can’t detect.

Dogs’ underwater smelling prowess makes them heroes and lifesavers while aiding search missions and conservation efforts.

Limitations to Scent Detection Underwater

Water dilutes and distorts scents

When odors travel through air, they form a cone that spreads out and becomes diluted over distance. However, when odor molecules enter water, they immediately begin dispersing in all directions, becoming diluted much faster than in air.

Additionally, factors like temperature, turbulence, and salinity can further distort or transport scents underwater, making it challenging for dogs to follow a scent trail in aquatic environments.

According to a 2018 study published in the Journal of Experimental Biology, trailing dogs had more difficulty following underwater scent trails compared to trails in air. Researchers found that even small increases in turbulence affected tracking performance.

They also noted that colder water temperatures improved scent detection somewhat by slowing odor dispersal.

Flowing water complicates tracking

The movement of water currents can rapidly carry scents away from their source. Rather than leaving a concentrated trail to follow, odors quickly become patchy and discontinuous when dispersed by flowing water.

This makes it much harder for canine sniffers to isolate and trail specific scents underwater.

A 2014 study in Applied Animal Behaviour Science tested trailing bloodhounds in both stagnant and moving water conditions. They found the dogs’ ability to follow scent trails deteriorated significantly when tested in flowing water versus still pools.

The researchers concluded that running water adds an extra layer of complexity for canine tracking.

Duration of submersion affects detection

The longer an item or person has been submerged, the more diluted and dispersed their scent usually becomes. One study published in Forensic Science International in 2013 tested dog teams searching for submerged human remains.

They found detection rates declined dramatically after the first day post-submersion, with very few remains located after 14 days underwater.

However, other factors like water flow rates can also impact scent persistence. In less turbulent conditions, dogs may be able to detect submerged scents for longer periods. Still, trailing underwater gets progressively more challenging the longer a scent has been dispersed in an aquatic environment.

Tips for Using Your Dog’s Nose in Water

Start training in shallow, calm water

When beginning water nosework training, start in an environment that will set your dog up for success. Choose a location with shallow, calm water such as a small pond, tidal pool, or bathtub. This allows your dog to focus on using his nose instead of worrying about swimming or deep water.

You can make the training even easier by standing in the water with your dog or providing a ramp for him to walk into and out of the water. Taking it slow in the initial stages prevents frustration and builds your dog’s confidence in using his super sniffer in a new environment.

Use floating targets at first

Dogs rely heavily on their sight when searching for targets in water. At first, use floating targets that are easy for your dog to see, like tennis balls, kongs, or bumpers. You can even add bright colors or attach ribbons to make them more visible.

Start with targets in clear water just below the surface. As your dog becomes proficient at locating these, gradually increase the depth and difficulty. Eventually, you can transition to fully submerged targets once your dog understands how to find them using his nose underwater.

Keep training sessions short

Dogs tire more quickly when swimming and searching in water. Limit initial water training sessions to 5-10 minutes, even for dogs that normally work longer on land. The mental stimulation and exertion of water nosework can be very fatiguing at first.

Watch for signs your dog is getting tired, like decreased focus or motivation. End each session on a positive note to avoid frustration and keep your dog engaged and eager to train. As conditioning improves over time, you can gradually increase session length.

Provide plenty of encouragement and rewards

Searching underwater is challenging for dogs, so provide lots of encouragement, praise, and rewards. Have a bounty of treats, toys, and play time ready for when your dog correctly locates a submerged target or exhibits nice effort and focus.

Getting in the water and playing with your dog after successful searches also helps reinforce his good work. Extra rewards keep training fun and boost your dog’s drive to use his incredible nose during water work.

Conclusion

In summary, science shows dogs can absolutely use their incredible sense of smell even when their noses are underwater. While water presents some challenges, the right training allows dogs to take advantage of their natural sniffing abilities.

With knowledge of how a dog’s nose works, plus realistic expectations about limitations, we can better utilize dogs’ scenting skills in water-based tracking, search and rescue, and detection work. We should also remember that just like on land, working underwater requires building up conditioning, experience, and stamina in our dogs over time through positive training techniques.

So the next time you see a dog enthusiastically splashing after a stick in a lake, remember – they are likely catching all kinds of fascinating scents beneath the water that we can only imagine! Their nose knows no bounds.