Introduction Senses include visual, olfactory, auditory and tactile. Humans primary sense is vision. Dogs primary sense is olfactory and auditory. Cats primary sense is all of them.
Visual Visual capability is not comparable to that of humans. They can perceive changes in light but not in clear forms. Canine and feline eyes are slightly different shapes. They have a third eyelid called the nictitating membrane. Its function is to protect them. They are not normally visual but in some dogs you can see them in the corner.
Canine Eyes Field of vision depends on the breed and head shape affecting the placement of the eyes. Brachycephalic dogs have very forward set eyes, with a wide overlap and narrow field of vision (180degrees). Dolichocephalic have more obliquely set eyes with small overlap and a greater field of vision (270degrees). This accounts for why sight-hounds trip over small obstacles when at full tilt. Mesaticephalic have intemediate set eyes with a field of vision 240degrees to 250degree. Thought to be 2D. Retina is dominated with rods with a peak sensitivity of 508nm. 95% of cells are rod.
Auditory Physiological functioning of the ear is the same as other mammals. Cats can hear more than dogs. They can hear into the ultrasonic range as it may help to locate their prey which use this as communication. Canine Ears Degree of ear mobility helps to rapidy pin-point the exact location of a sound by using 18 muscles. They can identify a sound much quicker than humans and hear sounds from four times the distance. Natural pointed ear shapes can hear more than the floppy ears.
Feline Ears Cats have a large pinna compared to body size. Helps to locate and collect sound. Pinna can rotate 180degrees. The cat cochlea has 40,000 nerve fibres which is 25% more than that of humans. They can discriminate between two sound sources very effectively. Helps to track and locate prey.
Olfaction (Smell) Dogs have a better sense of smell. Dogs can detect a drop of acetic acid diluted thousands of times. The capability of the dog depends on the breed. Dogs have 125->300 million olfactory receptors. Cats have 100 million olfactory receptors. Some dogs have been selectively bred for the ability to detect scents (e.g. blood hounds and beagles). Dogs have been trained to detect a wide range of odour from narcotics and explosives to human sweat and even cancer. Dogs can distinguish between two different types of scents: an air scent and a ground scent.. Air scent is intermittent so less obscured by competing scents. Ground scent is relatively permanent, but can be contaminated by other scents. Dogs and cats have several mechanisms to aid olfaction: Sniffing behaviour - disruption of normal breathing with rapid and short inhalations and exhalations, air is forced into a space above the subethmoidal shelf and traps the air. They both have a vomeronasal or Jacobsen's organ. This is a pair of fluid-filled sacs situated just behind the upper front teeth in the roof of the mouth. It is connected via nerves to the amygdala region of the hypothalamus. Highly sensitive to airborne pheromones and allows the animal to taste the smell. Cats have a Flehmen response. This is a behaviour we see when they are focussing on a smell. The cat raises its head slightly, draws back its upper lip and opens it mouth a little, sniffs and concentrates for a few moments.
Olfaction (Taste) The senses of smell and taste are closely linked and so they can gain more information about their food, Dogs can detect bitter, sweet, salty and sour foods but their most abundant taste is sweet. This is thought to be related to their omnivorous diet. Cats can taste bitter, salty and sour foods but are limited to their sweet detection. This is thought to be due to the fact they only eat meat. Sense of taste is relatively poor in both cats and dogs. Humans have 9000 taste buds. Dogs have only 1700 taste buds. Cats have even less with only 500 taste buds. Their sense of smell however is 30X better than a human. Cats and dogs prefer to eat warm food as freshly killed food is warm. Warm food also releases an aroma inducing the animal to feed.
Tactile (Touch) Well developed, especially in the skin. They have five categories of tactile receptors: Nociceptors (pain) Proprioreceptors (movement) Thermareceptors (temperature) Chemoreceptors (chemical) Mechanoreceptors (pressure) Tactile is one of the earliest senses to develop. Dogs and cats have motile whiskers. At the base of the whiskers are mechanoreceptors in the follicle which detect movement and disturbance of the whiskers. Whiskers provide protection for the muzzle and the ears. They can detect vibrations and air current changes. Cats have greater tactile senses than dogs. Cats have a range of specific tactile adaptations including the sensitivity of the paws and the whiskers and carpal hairs The whiskers (vibrissae) and carpal hairs are englarged hairs more than twice the thickness of ordinary hairs and emedded 3x deeper. They are richly supplied with nerve ending so give the cat information about anything they touch and pressures in the air. They are so sensitive that they detect air swirls and eddies around objects. Whiskers are mobile and move forward when inquisitive, threatening or testing something. Move backwards when defensive or avoiding something. A cat with damaged whiskers cannot kill cleanly at night and hit thins. Tend to misjudge the killing bite and trip over things in the environment.
Communication Dogs and cat communicate by using all of their senses. They communicate for a wide range of reasons such as social, ingestive, reproductive, care giving and territoriality. Dogs share communication with wide progenitor and closest relative (e.g. wolf). Domestic cats are different from their wild progenitor. African cats show limited communication to only territoriality and reproduction. Domestic cats developed greater communication skills as they live with in close proximity with other animals.
Olfactory Communication Dogs and cats have a very powerful olfactory sense that they use in many situations. Scent marking is a very good means of communicating information. Allows messages to be left in your absence. They do this by urine and faeces. Glandular secretions are also used (especially in cats) and they scratch objects to leave their scent. Olfaction is important in dogs for territorial and hierarchial reasons. They use sniffing to aid it.
Vocal Communication Has a wide range of functions in both dogs and cats. Tends to be contextual with the same vocalisation meaning different things with different expressions. Dogs bark, grunt, growl and howl. Cats purr, trill, meow, mating call, growl and hiss. Many species are able to learn to vocalise in response to certain stimuli. Such as whining for food and barking on command.
Visual Communication Dogs and cats communicate visually by posture, facial expression, tail language and alterations in coat. Communication can be harder in some dogs than others due to morphological differences e.g. hair, wrinkles. Cats haven't got this problem as we haven't changed them all that much. Cats also communicate with their eyes and ears.
Feline eyes large eyes in relation to skull and body size. Eyes are set well forward on their head. Cats have a wide visual and binocular field with their visual field being 295 degrees. This is because they have a curved cornea and slightly protruding eye. Cats are believed to be able to see in 3D so that they can detect motion as they are solo hunters. Allows them to judge distance during hunting. Cats peak sensitivity is about 501nm and 92% of cells are rods. They are not colour blind. The cat's eye utilises 50% more available light in the dark than humans. Due to the relatively short pupil-retina distance. They have a specialised reflective cell behind the retina called Tapidum lucidum acting as a mirror. They have more control over the amount of light they let into their eyes. Very sensitive so they can see in dim light. Greater control over their iris and they can narrow their pupuls to tight slits giving greater control over light input. Vertical slits rather than horizontal ones.