The first thing to note is that a cat’s sense of smell is about fourteen times stronger than a human. This is largely because a cat’s entire nasal organ is so much bigger than that of a human—despite the demure outer appearance, a cat’s olfactory system extends through nearly their entire head. Your cute kitten’s little head is essentially a giant walking nose—just keep that in mind.
Your cat’s sense of smell helps in:
- Survival—a cat can smell potential Enemies and dangers coming. Cats (along with snakes, lizards, and a large number of other mammals—though sometimes underdeveloped in them) have an organ known as the vomeronasal organ (popularly known as Jacobson’s organ). This essentially is a very strong receptor, primarily of pheromones, which are the chemical forms of communications between animals. This helps your cat sense predators (almost in what seems to a human like a “6thsense”), competition, mates, and prey. This gland is located in your cat’s mouth, which is why they will often seem to grimace or smile when sniffing out particular odors. Your cat may seem to grimace at certain things, but it does not necessarily mean it is one of the smells that cats hate!
- Hunting—even before your cat’s eyes were open, his nose was leading him to food—just born, kittens will locate their mothers and, more importantly, the nearest teat. Unlike primates, cats are largely olfactory hunters, whereas we humans are greater visual hunters (though cats are like most mammalian predators in that they, of course, see better at night than humans, because of their double reflective eyes). That is not to say cat eyes are inferior, but rather than relying as strongly on central vision for details, a cat’s eyes largely find their use detecting movement, not colors and details.
- Social Interaction— Cats who are spraying are actually sending a complex message to other cats in the area. They are saying “hey this is my space, bugger off or I scratch you” or “I’m a single male cat, in my late 3’s. I have a steady family, and my turn-ons include long strolls through the yard and a sunny driveway”. Cat spray is not one of the smells that cats hate, rather it is a manner of cat-mail
- Sexual Reproduction—the above mentioned Jocobson’s organ is primarily thought to be used forpheromone detection. Female cats, when “in heat” excrete a very powerful chemical signal that male cats can detect over miles. Male cats also, when they spray, leave behind a message about themselves that helps the female cats determine their qualification as a mate. Warning: does not work for humans. My girlfriend is still rather peeved about that.
Cats do have olfactory preferences, largely due to various evolutionary impulses. Whether it is foods they cannot digest or various potentially dangerous chemicals, a cat will avoid certain scents.
Smells that cats hate:
- Citrus—lemons, limes, oranges, and the like famously are cat repellents
- Bananas—rubbing a banana (or citrus) peel on a couch might keep your cat off (though it will start to smell like old rotten bananas).
- Dirty Litter Boxes—they do not smell great to humans either, but this is a particular smell that cats hate. A dirty litter box could drive your cat to make their own litter box, out of a rug or your favorite sweater left lying on the floor.
- Cayenne Pepper—as well as mustard and a variety of spicy foods (capsaicin is a toxin after all)
- Some Soaps & Deodorants—be careful what you clean your cat’s bowl or litter box with, because some cleaners will scare your cat away.
- Certain Plants—lavender, rue, geranium, absinthe or lemon thyme are examples of smells that cats hate in the plat world. Remember, of course, some plats cats love. Things like catnip (part of the mint family) and spider plants have a mildly hallucinogenic effect on your cats, and, like some of us in college, cannot get enough of them.
Remember, of course, cats are like people in that these are the typical smells that cats hate, but cats are still individuals. Some might dislike some more than others. So if you are trying to find a way to keep your cat from using your prize flowers as a litter box, you may need to try several different odors in different amounts to find out what works.