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Dogs sniffing
"Did you know the ability of dogs to detect scents varies between breeds?"

Why do dogs sniff?

Dogs love to sniff. Using their nose is often the highlight of their walks, if not dominating their entire day. Their ‘nosiness’, however, can be difficult for owners to comprehend and even, on occasion, be embarrassing. The dog nose truly is a wonderful scent apparatus, even if we don’t quite understand all of its abilities yet.

How dogs sniff

Dogs are born to sniff. The area of the canine brain that is devoted to analysing scent is 40 times greater than that of the human and dogs can identify smells at least 1,000 times better than we can! The dog’s superior sense of smell comes from 220 million olfactory receptors in its nose. Compared to the human’s paltry 5 million, it’s no wonder smell is considered to be the dog’s primary sense. When a dog sniffs, air is taken in and passes through the olfactory epithelium (nasal skin cells). These calls are also found in a special organ that dogs (and cats) possess, called the Jacobsen’s or vomeronasal organ. This organ is thought to be important in the detection of pheromones (body scents), perhaps giving the dog its tremendous ability to identify and recognise animals and people.

Did you know?

  • The ability of the dog to detect scents varies between breeds, with long-nosed dogs able to distinguish scents better than the short-faced ones. The Bloodhound is thought to have the best scent-detection abilities of all dogs while Gundogs (like Retrievers and Spaniels) spend most time sniffing when out on walks.
  • Each dog nose is unique, with its own distinct nostril shape and pattern of ridges and dimples. A canine nose print is as unique as a human fingerprint.
  • Dogs can distinguish the scent of individuals, both dogs and people. They can tell the difference between individual family members, even identical twins, purely by smell.
  • Dogs can tell from sniffing a tree of lamppost when a dog has passed, who it is and what status they have – male/female, top dog or not.
  • Dogs do not appear to distinguish between the regions of the human body which they sniff. Your armpits, to your dog, smell very similar to your feet!
  • A diet that is higher in fat and lower in protein than the typical dog food is thought to be beneficial to the dog’s scent-detecting ability, though it is only dogs who work as scent-detection dogs that may need to alter their nutrition.
  • Aromas can affect dogs. Lavender for instance, calms them down and reduces barking whereas rosemary increases it.  

Putting that nose to work

Dogs are used by humans to detect all sorts of things and, as we learn more about the extent of the canine sense of smell, we can guarantee that this canine detection list will expand:
  • Police dogs follow tracks of criminals or of people trapped in rubble after buildings have collapsed, whether alive or dead (sometimes referred to as cadaver dogs).
  • Quarantine dogs detect odours of prohibited substances entering the country, including fruit, live animals such as snakes, drugs and more.
  • Explosive-detector dogs seek explosive devices in public places or in war zones.
  • Medical alert dogs detect many physical conditions. They can detect low blood sugar levels in diabetes sufferers, for instance, due to the difference scent emitted.
  • Similarly, dogs can be trained to detect cancer. For instance, dogs can detect prostate cancer from a urine sample and lung cancer from a breath sample.
  • Bio-detection dogs detect microbial growth in buildings which, if left undiscovered may result in decay of building materials or cause respiratory distress in occupants.
  • Bed bug detection dogs can detect very early infestations of these unwanted creatures, useful for hotels.
  • Other diverse substances including termites, bees, CDs, mobile phones, truffles and more can all be detected by trained dogs.

When dogs are just too nosy!

There are occasions when the dog nose is just plain annoying to humans:
  • When we are out on a walk and they insist on stopping every few paces to sniff
  • And when visitors call and they insist on sticking their noses into embarrassing places

In these cases, it is up to owners to take charge. There is no doubt that dogs love to sniff, especially when out and about in their neighbourhood. Allow them plenty of sniffing time, to satisfy their needs, but if you want to move on, give them a command such as “Walk on” and reward them for obeying you.

If you are embarrassed by your dog’s sniffing habits, try to distract them. When visitors call, put your dog on a lead to control their movements. Teach them to say hello by sniffing the person’s hand and reward them for staying calm. While you may be embarrassed by your dog sniffing the bottoms of other dogs, this is perfectly normal dog behaviour! It is also normal for dogs to seek out areas of your home or items of clothing that smell of you. It helps them feel close to you, in your absence.

About Dr Joanne Righetti

Dr Joanne RighettiDr Joanne Righetti is an animal behaviourist, educating the public and professionals in all aspects of the human–animal relationship. Her background is in zoology, with a PhD in animal behaviour and a counselling diploma – qualifications which enable her to work with all sorts of animals – including the human variety! Joanne likes to help pet owners understand their pet's behaviour and solve any pet behaviour problems. She also consults to a variety of organisations including non-profit organisations, commercial companies and councils and is involved in a variety of media including regular spots on radio. Joanne is an honorary associate of the Faculty of Veterinary Sciences, University of Sydney. Find out more about Joanne at

Last updated: 24 April 2015 at 05:14 PM
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