Dogs can smell diseases such as diabetes and cancer, including prostate cancer, colorectal cancer and melanoma¹.
Dogs can smell about 10,000 times better than humans².
Dogs' noses are wet to help them absorb scent chemicals. Their nose secretes a special mucus, which they then lick to sample the smell, to then better understand what the smell is⁴.
A bloodhound's sense of smell is so accurate it can be used as evidence in a United State's court of law⁴.
Dogs have three eyelids. This third eyelid clears visibility in the front of the eye, acting as a "windshield-washer" of sorts, clears mucus and debris from the cornea, produces antibodies to fight infection, and protects the cornea from injury³.
To drink water, dogs plunge their tongue straight into the water, pull it to the rear and shovel the water into their throat.
The smell in a dog’s urine lets other dogs know if the one who left the message is young or old, male or female, healthy or sick, and happy or angry⁷.
Dogs can see colors! But behavioral tests show they can only perceive blue and yellow⁵.
Dogs can estimate the size of another dog by the sound of their growling⁶.
Sweat ducts in dogs’ paws are activated when it is too hot but there's not enough of them to cool down. This is also why dogs pant⁸.