Dogs: The Sensory Perspective

Andrew CostelloJohn CostelloTom EastawayNiamh McLaffertySai Chandra PadmanabuniFan ZhangLi ZhogyuanTim Zimmermann

Dogs: The Sensory Perspective

Dog Perception

Sensory - Senses– Now we could spend a whole semester just

looking at the senses, they are very rich and detailed.

Dogs: Visual Perception

Dogs: Visual Perception

Can pick out two colours:– Blue/Violet– Yellow

Can differentiate among shades of grey Unable to distinguish green, yellow, orange

and red

Dogs: Visual Perception

Dogs: Visual Perception

Dog Human

Distinguishing features of a dog eye (1)

The ora serrata is the serrated junction between the retina and the ciliary body. This junction marks the transition from the simple non-photosensitive area of the retina to the complex, multi-layered photosensitive region. In animals in which the region does not have a serrated appearance, it is called the ora ciliaris retinae.

Distinguishing features of a dog eye (2)

The Nictitating Membrane (Third Eyelid): Protection of the surface of the eye because

dogs use their head more actively than humans

Aspects of Canine Vision Greater divergence of the eye axis than

humans, enabling them to rotate their pupils farther in any direction

Visual acuity is poor their visual discrimination for moving objects is very high; dogs have been shown to be able to discriminate between humans at a range of between 800 and 900 m, however this range decreases to 500-600 m if the object is stationary.

Have good night vision: Canine’s biggest advantage

Seeing Eye Dogs

Most dogs have 20/75 eyesight Seeing eye dogs are bred for desirable

qualities such as eyesight and intelligence Certain breeds, such as Labradors, may

have closer to 20/20 vision and a suitable temperament for blind people

Eye Problems

Cherry Eye: Swelling the nictitating membrane (third eyelid)

Entropion: turning in of the edges of the eyelid (usually the lower eyelid) so that the lashes rub against the eye surface.

Ectopic Cilia: Abnormal eyelash growth, relatively common in dogs

Stinky Eyes: Excessive tearing and drainage around the eyes may have a foul odor from the discharge collecting on the hair and skin

Dogs: Auditory Perception

Dogs Hearing

The main organ of hearing is the ear.

Dogs Hearing

Differences between dogs ears and human’s.– Dogs ears are controlled by at least 18 muscles, this allows

the ears to tilt and rotate. Dogs erect ears amplify incoming sounds, therefore dogs with erect ears can hear better than dogs with floppy ears. Also the ability to swivel their ears helps their hearing.

– Dogs ears are an important for balance.– Differing form humans high pitched sounds can be

uncomfortable or even painful.– Some dogs hearing will deteriorate as getting older,

similarly to humans.

Dogs Hearing

Dogs frequency levels– Dogs can hear higher frequencies that humans,

for example they could hear the pre-stage of an earthquake with ultrasonic shockwaves over 20kHz, higher than what a human could hear.

– A dogs frequency range is typically considered to be between 40Hz and 65,000Hz.

– Frequencies higher than audio are referred to as ultrasonic, while frequencies below audio are referred to as infrasonic.

Dogs Hearing

Dogs ‘loudness’ tolerance– An important notion when considering hearing is

“Loudness”, which is a quality of sound that is primarily a psychological interpretation of the physical signal strength of a sound (amplitude).

– The loudness that dogs are capable of being heard are typically 10dB and 150dB.

Hearing Threshold

Term DecibelsLong term 85dB

Short term 120dB

There is a problem in the research into what a dogs hearing threshold as we do not know what they can hear. The following are just assumptions made.

Dogs Hearing

The loudness tolerance depends on the frequency and vice versa.

Humans hear frequencies between about 20 cycles/sec to 20,000 cycles/sec at 130db (very loud). This shrinks to a range of about 700 cycles/sec to 6000 cycles/sec at 0db, we can assume dogs have a dynamic range of loudness.

In conclusion, Measurements of physiological responses to sound (or light) are very difficult and complicated to quantify.

Dogs: Olfactory Perception

Anatomy of the nose

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Anatomy of the nose

The nasal cavity is essentially a tube with a wall established by several bones of the skull. The borders of the nasal cavity are as follows:

Caudal: The cribrifrom plate of the ethmoid bone.

Ventral: Continuous with the nasopharynx.

Dorsal: The maxilla and the palatine processes of the incisive bone.

Rostral: The median septum is a continuation of the ethmoid bone. The median septum is made up of hyaline cartilage, and divides the nasal cavity into left and right halves.

Dogs versus Humans

A dog interprets the world predominantly by smell, whereas a human interprets it by sight

While a dog's brain is only one-tenth the size of a human brain, the part that controls smell is 40 times larger than in humans.

Dogs versus Humans

Dog’s sense of smell is about 1,000 to 10,000,000 times more sensitive than a human’s (depending on the breed).

A human has about 5 million scent glands, compared to a dog, who has anywhere from 125 million to 300 million (depending on the breed).

Dog receptors versus Human

What is Olfaction?

Olfaction, the act or process of smelling, is a dog’s primary special sense.

Olfactory nerves that ultimately connect with the highly developed olfactory lobe in the dog’s brain.

Why is a dog’s nose moist?

A dog’s nose is normally cool and moist. The moisture secreted by mucous glands in the nasal cavity captures and dissolves molecules in the air and brings them into contact with the specialized olfactory epithelium inside the nose.

Other uses for the Dogs noses

Olfactory receptor cells in the vomeronasal organ also send impulses to the region of the hypothalamus associated with sexual and social behaviors.

Dogs smell is vital for the Dog !

& the lighter side !!

Dogs: Gustative Perception

Taste Buds in Dogs

Animal Taste Buds

Human 9000 – good sense of taste

Dog 1700 – stronger reliance on smell than taste

Cat 470 – very weak sense of taste

Most of a dog’s taste buds are on the tip of its tongue

Some at back of tongue, some on palate (soft part of roof of mouth)

Reliance on Smell for Food

Dogs wolf down nice-smelling foods Dogs eat foods with weak smells more slowly Link between taste and smell (similar link exists in

humans) Even if it smells bad, they don’t care >>>>>>>>>

A Salt on the Senses

Humans seek out salt – viz. salty snacks such as crisps

Dogs get enough sodium from meat Less developed salt receptors

Sweet Doggie

Omnivores (only ~80% meat in diet) Dogs’ sweet taste is for a chemical called

furaneol (found in tomatoes and other fruit) In the wild dogs frequently supplement diet

with fruit and berries

Water

Tips of tongues specifically tuned to taste water

This part of tongue used to scoop water up Shared with other carnivores, but not with

humans Especially sensitive after eating salty or

sugary foods

The Bitter End

Dislike bitter taste Deterrent sprays to prevent chewing furniture