How Long Can a Dog Follow a Scent: Understanding Your Dogs Nose

dog smelling ground

It is well known that dogs can be great at tracking down a scent. Their nose is their biggest weapon and they constantly use it. It seems like a dog can sniff around forever, but how long can a dog follow a scent.

Dogs can follow a scent weeks after it has been laid. If the initial scent was strong enough and the breed of dog was a natural sniffer that had been well trained they would be able to follow the scent for hundreds of hours.

The length of time in which a dog can follow a scent is dependent on many factors. There are various components that make a smell strong enough to follow and different breeds of dog have better smell receptors. We explore the understanding of your dog’s nose and how long a dog can follow a scent for.


How Does A Dog Track A Scent

Dogs have an incredibly sensitive nose, in fact, most of what makes them great at tracking a scent comes from the way their nose collaborates with their brain. As most owners will know, their dog has a soft wet nose. The tracking of a scent is something that a dog can easily do, as a dog smells so much more than where a person has been.

The part of the brain which processes smell is called the olfactory bulb. This section of the brain inside a dog is many times larger than that of a human, meaning a dog is able to process a huge amount of different smells all at once. This process essentially tells a story of not only the location of someone at a certain time but also what they were doing, how they were feeling, what they were wearing and many more distinguishable features. These smells can then be remembered and matched with new smells later on. Although the ability to remember different smells is one of great importance when tracking a scent, the structure of their nose also helps them to follow a scent for a long time. Direction is also a feature of a dogs tracking ability, each nostril can smell independently, meaning that a dog can tell which direction the scent is coming from. All this enables them to potentially track something indefinitely, providing the scent is still present.

How Long Does Scent Last

The length of time a dog can follow a scent is highly dependent on how long the scent itself will last. This is dependent on a few factors including, weather conditions and the material in which it attaches. There is much debate around how long a dog can smell a scent and a common answer appears to be around 1 month. However this entirely depends on whether the material is still letting off gases, in particular, decomposing bodies will continue given scent off for many years.

Another factor influencing how long a dog can track someone or something is the material in which they stand on. Some believe that a scent trail will disappear quickly once a person walks on a road or pavement, as apposed to a wood area where scent can be more easily distributed.

What Material Holds Scent The Best

A smell is formed through the release of gases into the air. These gases can be released through oils on the surface of a material. The amount a material smells is down to its ability to release gases into the air. Fabrics are generally good at holding smells, as the gases are released within the fibres of the material. Odours can linger in a certain place and the ability of a material to release a scent will help a dog to track it in a certain direction.

Does rain wash Away Scent

Weather is a smells worst enemy. Because smells are made of gases any sort of wind or rain will prevent scent from lingering on something. Hot days will also reduce the amount of time smells linger, in fact, cold damp conditions are the best for keeping scents around. A study conducted by the University of Technology, Sydney, experimented with blood samples on both concrete and wood. These samples were subjected to natural weathering over a period of 3 months. Trained Cadaver and Blood detection dogs were used to detect blood droplets on these samples. The data from the experiment indicated that both samples were well weathered over the 3 months including 505mm of rain falling on the concrete samples and 337mm falling on the wooden samples. This study concluded that despite the dogs being able to detect the blood after initial rainfall, they were not able to detect the blood samples on concrete after 1 month and after 1 week on wood, they highlighted rainfall as being a factor in the loss of scent. The limitations of this study were the fact that they did not expose the dogs to the blood samples prior to the weathering process.

It’s All In The Training

Training is an extremely important part of how long a dog can track a scent for. As we know dogs have an amazing sense of smell but they still have to be trained to be able to follow a trail. If a scent is uninteresting to a dog naturally they won’t follow it, dogs are trained to recognise one particular scent and either follow it or find its location.

According to “How Stuff Works”, SAR (search and rescue) dogs are trained in two unique ways. Each way has its own benefit and depending on the case they choose a particular dog.

Tracking Dogs – These dogs are trained to identify a scent trail and follow it towards the missing person. This type of search requires a starting point and a reference scent to tell the dog what smell it needs to track. When searching for missing persons, an item of clothing is usually used as the reference scent, as skin particles will be present on the clothing. As a person travels, skin particles will fall onto nearby foliage and the ground, this is why these particular dogs are very nose to the ground. The length of time a dog can track this way depends on the scent particles being left behind by the person, but essentially if the person is constantly travelling and leaving behind a scent that is still fresh, a dog can track them indefinitely.

Air Scent Dogs – These dogs are trained to identify a scent from a distance, they don’t necessarily require a trail to follow. The key factor to the success of this type of scent tracking is the ability for a dog to pick up scent particles in the air, by this means they can then discover the location of the source. Because scent particles will dissipate further apart whilst travelling in the air, scent dogs will follow the largest concentration of these particles in the hope that this is the location of the source. These dogs are mainly used to find missing persons who are trapped underneath something such as buildings and avalanches. They are also used to find decomposing bodies, which can be buried or trapped underwater, these bodies give off gases that a dog can then sense travelling in the air. The amount of time in which a dog can track a scent this way is dependent on how long the source emits a smell and the direction of the travelling scent particles.

How To Improve Your Dog’s Sense Of Smell

How long your dog can smell for will depend mainly on the training you give them. Its easy for some owner to assume just because your dog has an amazing sense of smell they can instantly find things you hide. Improving your dogs sense of smell can be a fun activity for you do do with your dog and it can also provide you with an incredible tool. With all training comes a huge amount of patience so here are some tips for training you dog to follow a smell.

  • Use what motivates your dog the most. If your dog enjoys playing with their toys more than treats then this is what you should use to train them to follow a scent.
  • Use positive re-reinforcement to give your pooch the idea that what they are doing is satisfying you and they will continue to want to please you.
  • Use an area that has no distractions or overpowering smells. This way your dog will be able to learn the basics, enabling you to move on to more complicated environments.
  • Start with basic games, such as hiding a treat under a cup or putting a toy under a box. Don’t assume you can just hide their toy somewhere and they will find it.
  • Remember dogs live in the moment and repeating the same thing over and over again may not be what they want. Take breaks to keep everything fresh and your pooch excited.
  • If your dog is not getting the idea, don’t be afraid to help them out. In the early stages of training, we all need a little help from time to time.

Have a look at this video, as it shows a great way to train your dog to follow a scent.


The length of time a dog is able to track a smell can be dependent on many factors. Despite these factors it is still apparent that dogs have an incredible sense of smell and they see the world around them differently to us. If you enjoyed this article why not check out some of our other posts.


Baree Chilcote, et al. Profiling the scent of weathered training aids for blood-detection dogs. Science and Justice Journal. Volume 58, Issue 2. 2018





Dean Lissaman

As a child I grew up around dogs and have loved them ever since. I now have a beloved Golden Retriever who enjoys exploring the outside world. Being an outdoor enthusiast has inspired me to create the ultimate resource on relating both dogs and the outdoors. For more information on me check out my about page.

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