Dogs: The Sensory Perspective
Andrew Costello
John Costello
Tom Eastaway
Niamh McLafferty
Sai Chandra Padmanabuni
Fan Zhang
Li Zhogyuan
Tim Zimmermann
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
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.
Term
Decibels
Long term
85dB
Short term
120dB
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
.
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