We need to understand dogs and cats smell the world rather than see it. Dr Kat Littlewood, veterinary specialist at Massey University, told RNZ's Nine to Noon.
How pets see the world
Humans have 5 million scent receptors, dogs have 300 million, she said.
"That's going to give them a huge capacity to see the world, but in scent form.
"They have a huge part of their brain that's devoted to smell, so they can analyse all the different smells and start to layer smells, so it is a picture, but in smell form. We can't even imagine what that's like."
Each nostril can pick up different things from different directions so that dogs can start to build a picture of the world around them, she said.
Cats leave their scent as kind a "time share" arrangement.
"Cats use urine, urine spraying, and they might scratch things. Sometimes, when they're scratching, they're leaving marks with these glands around their claws to tell other cats things or to send messages around the place, because smell is how they talk, how they speak."
Cats will avoid conflict if possible and this timeshare technique helps them manage territory, she said.
"They'll send messages around the place saying, this is where I live, don't come into my territory, or I visit at this time of day, you can visit at a different time of day."
Dog owners should allow their pets to embrace their world of scent, she said.
"Instead of trying to get to a destination, or pull them along by their lead, let them have a little bit more of a loose leash and sniff the world. Because that's their way of seeing things.
"I went for a walk to see a beautiful, stunning spring morning. How they see the spring morning is having these sniffy walks."
Humans are "touchy-feely", she said, as we descend from primates. Not so dogs.
"They can smell anxiety, they can smell fear, so they can get that really cool cue from you of whether they should be coming up to you or not."
Let a dog come to you, she said.
"A little bit of a pat, a stroke, but allowing for them to move away when they want to."
Because cats build up a data base of smells, the deep spring clean can be disruptive, she said.
"Having their smell around their house is really important, if we do a full clean, we're getting rid of a lot of those scents that they've left around the place to make them feel comfortable."
Over-cleaning can lead to your moggy replacing those smells with a spraying, scratching spree, she said.
"If we are going to do a spring clean, doing it room-by-room, and not doing the whole house all at once, so that they still have some scent."
Scratching serves two purposes for cats, she said.
"One is to get rid of this claw sheath, they shed their claws every so often."
They also have scent glands around the claws, she said.
"They might scratch outside, wooden posts, power poles, that kind of thing, to leave little marks of this is mine, or I was here."
Sign up for Ngā Pitopito Kōrero, a daily newsletter curated by our editors and delivered straight to your inbox every weekday.