The noses of trained dogs are sensitive enough to identify cancer indicators in a person's breath, urine, and blood at very low quantities, as low as parts per trillion.
A wolf's sense of smell, which is up to 100,000 times more acute than a human's, is even more remarkable. A wolf can detect scents up to 300 yards (or one mile) away under the correct circumstances.
The smell of blood and game carcasses Some horses do not like the smell of blood or even seeing an elk carcass.
When kiwis probe the forest floor in search of food, they are guided by smell rather than sight.
Predators such as Lions and Hyenas can scent blood or carcasses from a great distance away and combined with the sense of hearing they will choose to react to the scent.
Cows can smell blood from up to 5 miles away and hear low and high-frequency sounds much better than humans can.
It is generally known that the smell of mammalian blood repels prey animals like mice and rats while attracting top predators like tigers and wolves.
Although it has been demonstrated that snakes can sense menstruation, according to Breitweiser, a reptile's capacity to detect menstruation mostly depends on their sense of smell.