APSC 3064 - Exam 1

Pupillary Light Reflex

The size of the pupil at rest represents a balance between two antagonistic forces:

The amount of incident light and the emotional status of the patient

Miosis

The amount of incident light stimulating the retina and influencing the oculomotor neurons to CONSTRICT the pupil

Parasympathetic innervation through CN III

Mydriasis

The emotional status of the patient which influences te sympathetic system and causes pupillary dilation

Resting Pupil

BOTH pupillary dilator and antagonistic pupillary sphincter are active

Pupillary Dilator

Sympathetic System

Pupillary Sphincter

Parasympathetic System

Which Pupillary muscle is the more powerful?

Pupillary Sphincter (constrictor)

If a bright light is shone into one eye at a time, what happens?

BOTH pupils constrict, with a DIRECT response in the tested eye being slightly stronger than a indirect response in the opposite eye

"The Dazzle Reflex"

When a bright light is initially flashed into the eye, a blink response occurs

"The Pupillary Escape"

When a poor quality source is used, the stimulated pupil may dilate slightly with continued stimulation

Why does the Indirect Response Occur?

Direct stimulus of the left eye results in an indirect constriction of the right pupil

Stimulation of the contralateral CN III parasympathetic nucleus results from some fibers of the CN II that cross over

The Menace Response

Cortically mediated eyelid closure produced by a threatening or unexpected gesture or action suddenly appearing in the near visual field

LEARNED response, presents from 6-12 wks of age

Menace Response Pathway

Visual stimulus is relayed contralaterally in CN II to the occipital cortex via the thalamus

The response to the stimulation is initiated via the motor cortex which stimulates the ipsilateral facial nerve (CN VII) to cause eyelid closure

If there is pupillary reflex...

check subcortical structures

If there is no menace response...

check cerebral cortex

4 Basic Tissues in the Body

Epithelial

Connective

Muscle

Nervous

Epithelial

Covers the body surface, lines body cavities and forms glands and other structures

NOT penetrated by blood vessels, receive nutrition and discharge waste by diffusion via blood vessels in neighboring tissue

Connective Tissue

Most abundant, widely distributed and varied type.

Includes loose connective tissue, fat, cartilage, bone, bone marrow, blood, and fibrous tissues

Ehlers-Danlos Syndrome

connective tissue disorder

fragile, stretchy and loose skin caused by a genetic defect in the production of collagen fibers

Glands

Specialized cell, group of cells, or organ of endothelial origin that selectively removes materials from the blood concentrates or alters them, and secretes them

Exocrine Glands

Secretion outside the body (ducts); saliva, digestive secretions, tears

Endocrine Glands

Secretions within the body -> bloodstream

HORMONES

Sagittal Plane

a plane that runs the length of the body and divides it into left and right parts

NOT NECESSARILY EQUAL HALVES

Medial Plane

Plane that runs down the center of the body length wise and divides it into equal left and right halves

Transverse Plane

A plane across the body that divides it into cranial and caudal parts that are NOT necessarily equal

Horizontal Plane

A plane at right angle to the sagittal and transverse planes; divides the body into dorsal and ventral parts that are not necessarily equal

Dorsal Cavity Consists of

Cranial and Vertebral Cavity

Ventral Cavity Consists of

Thoracic Cavity

Abdominal Cavity

Pelvic Cavity

Peritoneum

serous membrane similar to that surrounding the heart and lungs in the abdominopelvic cavity

Lines the abdominal cavity and extends to the pelvic cavity

Peritoneal Cavity

space between partial peritoneum (attached to abdomen wall) and visceral peritoneum (wrapped around internal organs)

Ascites/Abdominal Effusion

Accumulation of fluid in the peritoneal cavity that exceeds 25mL

Transudate

accumulation of fluid due to a hydrostatic imbalance between the intravascular and extravascular compartments despite normal vascular permeability

little protein in the fluid

Edema, hypoproteinemia

CLEAR

Exudate

Accumulation of fluid due to increased vascular permeability, high protein content

Integumentary System

Consists of the skin, mucous membranes, hair, and nails

What vitamin can dogs and cats not synthesize?

Vitamin D

They must receive it in their diet

Three layers of skin

epidermis, dermis, hypodermis

Shedding in Dogs...

occurs when dog's hair reaches a certain length and stops growing then it "dies"

What are the two glands found in a dog's dermal skin layer?

Apocrine glands - seal the outer layer of the epidermis, pheromone secretion

Merocrine Glands - in the pads of the paws, watery secretion similar to sweat

What are the two types of hair in coats?

Secondary hairs - short fluffy hair, undercoat

Primary Hairs - longer and stiffer outer hairs

What is a dog's "winter coat"?

When a dog's rate of hair growth decreases, usually when the day length shortens

When does a dog lose their winter coat?

Usually as day length increases

Rate of growth increases so shedding occurs at a faster rate

What is the integumentary system a good indicator of?

Overall indicator of good health and nutritional status

Skin should be clean, pliable and free from dirt, sores, excessive oil or dryness

Coat should be bright, clean, consistent and have a healthy shine

About how many bones are in a cat?

245

About how many bones are in a dog?

319

What are the major functions of the skeleton?

Protects internal organs

Support the body

Provide attachment sites for muscles

The skeleton is ...

a dynamic structure throughout lifetime continuously remodeled

What are the specialized cells in the skeleton?

Osteoblasts

Osteoclasts

Chondrocytes

What do the specialized cells in in the skeletal system do?

Preserve the structural integrity of a skeletal system

What do osteoblasts do?

Bone formation

What do osteoclasts do?

bone resorption

break down tissue in bone

calcium in bone -> blood

What do chondrocytes do?

maintain cartilage

What are additional roles of the skeletal system?

Mineral Bank: Ca and P

Blood Production

Acid-Base Balance

Detoxification

Sound Management

What bones make up the forequarters?

Scapula

Humerus

Radius and Ulna

Carpus

Paws

What affects gait?

The angulation of shoulder

What bones make up the hindquarters?

Sacrum, Ilium, Ischium, Pubis

Femur

Tibia/Fibula

Tarsus

Paws

What is angulation?

The angles created by the bones meeting at various joints, especially at the shoulder, stifle and hock

What is forechest in dogs?

The portion of the dog that show in font of the forelegs, the amount varies by breed, size of their chest

What is shoulder layback in dogs?

The angle at which the scapula lies against the ribcage

What is the USUAL angle for the shoulder layback in dogs?

45 Degrees

Does not apply to all breeds

What is the shoulder angle?

The angle between shoulder and humerus

What are the different dog breeds with different shoulder angles?

Achondroplastic Breeds

Working Breeds

Gallopping Breeds

Describe Achondroplastic breeds?

Dachshunds, corgis

Shoulder angle of about 90 degrees

Describe Working Breeds?

Retrievers, Dobermann

Have a more open angles shoulder angle

humerus needs to be long enough to place elbow properly under the body

Describe Galloping Breeds?

Greyhounds, Irish Wolfhound

A more open shoulder because the upper arm drops sharply.

double suspension gallop

Explain how front angulation can affect movement

The steeper the angle of the shoulder blade, the LESS extension of the front leg

What is the Pelvic Angle?

length and set of the pelvic girdle in relation to the spine often affect the angulation of the whole hindquarters

What is a moderate slope in the pelvic angle?

allows a smooth transition from the back through the croup to the hindlegs

About 30 or less

What is the standard angle for the hindquarters to be in line with angulation in the forequarters?

90-110 degrees

What is the rear or stifle joint angle?

Measured along longitudinal axes femur and tibia/fibula

110-130 degree

What is hindquarter angulation or the pelvic slope?

The angle of the pelvis from the horizontal

30 or less than 30 degrees

What happens when pelvic angulation is too steep?

the thrust moves upwards instead of forwards

Causes the back to rise during movement; rear extension is also restricted

What happens when pelvic angulation has a good slope?

a good swing forwards and backwards, allowing for a powerful drive

What happens when pelvic angulation is too flat?

Insufficient thrust forward

What is gait?

pattern of footsteps at various rates of speed, each pattern distinguished by a particular rhythm and footfall

What are examples of different gaits?

Walk

Trot

Gallop

Amble

Pace

Canter

What is the flying trot?

In German Shepherds

All 4 feet are off the ground for a brief period of time

Need extreme angulation for the flying trot

How do we analyze gaits?

Kinematic Gate Analysis

Kinetic Gait Analysis

What is Kinematic gait analysis?

Quantifies the positions, velocities, acceleration/deceleration and angles of various anatomic structures in space

What is Kinetic Gait Analysis?

measures the ground reaction forces that are the result of an individual's step

Cats have more lumbar and thoracic vertebrae, what does this do?

Allows for higher spinal mobility and flexibility

What are found between cats vertebrae?

Elastic Discs that are useful for cushioning and jump landings

Which vertebra allows up and down movement of the head?

First Cervical Vertebra

C-1, Atlas

Which vertebra allows side to side movement of the head?

Second Cervical Vertebra

C-2, Axis

What is Intervertebral Disk Disease?

degenerative disease of the spinal column

compression of the spinal cord and spinal nerves

Which dog breeds' spinal disks begin degenerating early on?

Small Breeds

Dachshund, Beagle, Shih Tzu

Where are herniated disks most common?

In the neck and back

What is Type 1 IVDD?

The outer layer of the disk hardens and damages the disk, allowing it to break easily

What is type II IVDD?

The discs slowly harden over time and beginning to break down and bulge, putting pressure on the spinal cord

What is cervical spondylomyelopathy?

Cervical vertebral malformation-malarticulation

A compression of the cervical spinal cord segments

What are the two forms of Cervical Spondylomyelopathy?

Disc Associated Wobbler Syndrome

Bony Associated Cervical Spondylomyelopathy

What is wobbler syndrome?

Ventral compression of the spinal cord due to protrusion of one or more caudal cervical discs, "wobbly gait"

Middle aged, large breed dogs

What is the vestigial clavicle in cats?

Enhances mobility of front legs needed for hunting

What are rotating carpals in cats?

Allow more varied use of front paws than dogs have

What are growth plates in dogs?

Produce cartilage, which is converted to bone as the dog grows

When do growth plates close?

Late puberty

What happens when a dogs is spayed or neutered prior to puberty?

A delay in the closing of the growth plates

More likely to suffer from orthopedic problems

What does digitigrade mean?

Animals that walk on their toes

What is carpal hyperextension?

flat-footed condition when animals walk on the palmar surface of its wrists

What causes carpal hyperextension?

a traumatic event that ruptures the palmar ligaments

or

ligament degeneration

What allows the contraction and extension of claws in cats?

An elastic ligament between distal end of P3 and P2