The cat’s nose
Photo by polandeze (Flickr) – original photo
Smells (a chemical sense7), odors, call them what you like are important to a cat. A cat has an excellent sense of smell. At close range a cat uses smell over sight, in my experience, as cats have poor near sight (see cat eyes). Watch them eat food. A kitten that is being nursed can tell the difference in smell between its mother’s nipples7.
On an anatomical level the sensitivity of the cat’s nose is demonstrated by the size of its olfactory epithelium. The epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body1 including the nose.
|Species||Size of olfactory epithelium||Scent receptors||Sensitivity|
|Human||2 -4 cm² (or 10 cm² 4 this conflicts)||5 million|
|Cat2||20 cm²||200 million||20 times better than humans|
|Dog3||up to 170 cm² 4||220 million||50 – 1,000 times better than humans6|
The cat’s nose is far more sensitive than the nose of humans. The dog uses its sense of smell for tracking while the cat uses it mainly for:
- identifying other cats and us (see picture below)
- recognition of threatening odors
- importantly, as an appetite stimulus5
Cats are particularly attracted to garlic and onion that is used in commercial cat food flavourings. Cats hate the smell of mothballs and orange peel5. Please note though, the story of cats poisoned by mothballs that they ate.
Some cat breeds have to meet breed standards in respect of nose colour, the most obvious occurrence of this being for the pointed cats e.g. Siamese cats that are blue (dilute black) or seal (dark brown) pointed. The Savannah cat has a marvellously dark nose colour (I am not talking of the nose leather but the whole of the cats nose).
There are two passages, one for each nostril that open out into the throat. The nasal cavity is lined with a mucous membrane that contains blood vessels and nerves. This “blanket” is the first defence against bacteria and foreign bodies etc.
As mentioned in the introduction the inside of the nose is lined with the epithelium containing receptors.
In mammals, nostrils contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation9. The cat is a mammal.
This exterior view of the cats nose shows the nasal plane referred to by breeders as the “nose leather”. The equivalent of the philtrum in people is the vertical groove in the upper lip just under the nose. It is formed where the nasomedial and maxillary processes meet during embryonic development. It has no apparent function but is very obvious8.
The cat’s sniff is an important aid in maximising the reception of odours. Sniffing disrupts breathing and allows the odour particles to stay in the nose longer. My cat, Charlie, is a great sniffer and he has a long nose that I construe as meaning that he has a greater area of epithelium.
When a cat sniffs air it is forced into the bony pocket of the subethmoidal shelf, which traps the air when it is inhaled rather than it passing into the lungs. This allows the scent receptors in the cats nose to thoroughly detect the odour and pass the information to the brain where it is analysed.
Relying, as the cat does, on scent, it needs an efficient system for the purpose and it has an additional organ called the vomeronasal organ, which is also referred to as Jacob’s Organ. Other mammals have it also.
It is situated in the roof of the mouth and is made up of two small, fluid filled sacs. It is connected to the mouth and the nasal cavities via two nasopalatine canals (ducts), which open into the mouth just behind the upper incisor teeth.
Jacob’s organ contains receptor cells. These cells send information via nerves to the amygdala region of the hypothalamus which is part of the brain. The hypothalamus is concerned with sexual, social and feeding activities.
When a cat uses this organ it will adopt what seems to be a sneer with the mouth slightly open. The cat is still, it may wrinkle its nose and it concentrates. This is called the Flehmen response. It is also called gaping. The cat may taste the object that is being analysed by licking it. This further aids the cat. Cats also taste scent when they, for example, lick us.
The cats nose — Sources:
2. The Cat, Its Behavior, Nutrition & Health by Linda P Case
3. http://www.nspca.co.za/page.aspx?Id=116&CateId=15&Category= Information&SubCateId=98&SubCategory=Fireworks
5. The Cat Owner’s Home Veterinary Handbook by Drs Carlson and Giffin
7. Encyclopedia of the Cat by Dr Bruce Fogle