6823 ANIMAL SCIENCE II – SMALL
ANIMAL
COURSE:
ESSENTIAL STANDARD:
5.00
36%
C2
Objective:
5.01
16%
C2
UNIT C
Anatomy and Physiology
Discuss the role of major systems of small
animals.
Discuss the role of major body systems of small
animals.
References: Small Animal Care and Management, 2nd Edition, 2002. Dean M Warren, Delmar
Publishers, Albany, New York, 12212-5015. pp. 64-67, 98-99, 117, 137, 147, 169, 178,
183, 188, 195, 202, 211, 220, 240-242, 255, 259, 278, 299-303, 306-307, 335, 341343,381-382.
Modern Livestock and Poultry Production, 7th edition, 2004. James R. Gillespie, Thomson
Delmar Learning, Clifton Park, New York, 12065-2919. pp. 122-123.
Introduction to Livestock and Companion Animals, 3rd Edition, 2004. Jasper Lee, Prentice
Hall Interstate, Upper Saddle River, New Jersey 07458. pp. 40-50, 114-127.
A.
Basic Anatomy terminology for small animals
1.
Cheek – The fleshy side of the face below the eye and above and to the side of the
mouth.
2.
Dewlap – The loose fold of skin under the chin of an animal, most prominent in
female rabbits.
3.
Elbow – The upper joint of the front leg just below the shoulder.
4.
Flank – The fleshy part of the side between the ribs and the rump (croup).
5.
Foot pad – The part of the foot that the animal walks on.
6.
Guard hairs – The longer, coarse hairs above the shorter under-fur of an animal that
protects the animal and under-fur from rain and cold.
7.
Hock – The tarsal joint or large joint halfway up the hind limb
8.
Muzzle – The projecting jaw that contains the nose and mouth in some animals.
9.
Nose pad – The tip of the nose that may be sensitive and useful for investigating food,
water, or unfamiliar objects. (Called nose leather in cats).
10. Rump – The upper rounded part of the hindquarter (also called the croup).
11. Shoulder – The part of an animal’s body just above the elbow of the foreleg.
12. Stifle – The joint next above the hock in the hind leg of a four footed animal.
13. Thigh – The hind limb extending from the rump to the hock.
14. Whiskers – The long projecting hairs or bristles growing near the mouth of an animal.
B. Basic Anatomy terminology for birds
1. Crown – The topmost part of the head
2. Ear covert – The feathers covering the ears.
3. Nape – The back of the neck.
4. Orbital ring – A ring encircling the eye of many birds.
C. Basic Anatomy terminology for fish, Amphibians, and Reptiles
1. Brille – The transparent layer permanently covering the eye that serves as the eyelid for
snakes
2. Fins – The web of skin supported with bone or cartilage rods that enable a fish to move
through the water.
3. Gills – The major organ of the respiratory system of fish that allows them to breathe without
lungs.
4. Scales – Extensions of the epidermal layer of skin that have been modified to provide
protection. (Fish and reptiles may have some type of scales).
5. Scutes – Epidermal scales found on turtles.
D. Skeletal Anatomy
1.
Skeletal System – Bones
a. Axial skeleton – vertebral column, ribs, sternum and skull
b. Pectoral limb – front limbs including shoulders, legs and feet. Bones are scapula
(shoulder blade), humerus (arm), radius and ulna (forearm), carpals, metacarpals and
phalanges (toes).
c. Pelvic limb – rear legs and pelvic bones including femur (upper leg bone), tibia and fibula
(lower leg bones), tarsals (hocks), metatarsals (feet) and phalanges (toes).
2. Skeletal System – Structure and Purpose
a. Purposes – protect vital body organs and give form or shape to body
(1) Skull protects brain, ribs protect lungs and internal organs
(2) Spinal column or backbone protects the spinal cord and provides shape to the
animal.
b. Structure consist of bones, cartilage, and joints
3. Birds have some unique bones unlike mammals.
a. Most birds have a skull bone that elongates toward the front of the head.
b. Some birds have a skull with an upper beak fused to it while other birds have hinged on
both upper and lower (mandibles) giving it more flexibility
E. Internal Anatomy
1. Heart- major organ in the circulatory system
a. Made up of three muscle layers: myocardium – second layer muscle that makes
up the thickness of the heart, endocardium- thin layer inside myocardium, and
epicardium- thin cover over the myocardium, or main heart muscle.
b. Other parts to the circulatory system are the arteries, capillaries, vein, and
blood. They all move nutrient, metabolic waste, and oxygen around. Another
important role circulatory system plays is protection against microbes and
injury.
2. Kidneys and bladder- part of the excretory system that rids the body of waste. In
addition, the kidneys maintain chemical composition, volume of blood, and tissue
fluid.
3. Stomach and intestines- major part of digestive system, which breaks the food down
into smaller pieces to be used by the body. Nutrients are gleaned from these food
materials.
4. Lungs - part of the respiratory system where the oxygen is taken in by the nose,
passed on to the lungs and then goes into the blood.
5. Brains, spinal cord, and nerves make up the nervous system. The coordinator of all
body activities regulates other systems, and controls memory and learning.
6. Ovaries (female) and testes (male) make up the reproductive system to produce new
individuals of the same species. Ovaries produce eggs and testes produce sperm.
7. Muscles make up the muscular system that gives the body its movement, posture,
support, and produces heat.
F. Digestive system
1. Non-ruminants are referred to as single-stomached or monogastric animals.
2. The digestive system of rabbits and birds are classified as non-ruminants even though
their system is slightly different.
a. Rabbits have a digestive system similar to a horse in that they have a large cecum
(place where small and large intestines join) with bacteria present.
a. Therefore, rabbits can eat more high-quality roughage material than other
small animals and convert them to nutrients.
b. Rabbits must maintain levels of bacteria in the cecum for digestive process and
health. Rabbits eat undigested feces (coprophagy) to help bacterial action.
b. Birds have a unique system for breaking down the seed and food they eat.
a. Birds do not have teeth. Saliva is added to assist with swallowing, but very
little breakdown of food occurs in the mouth.
b. The largest digestive organ for birds is the gizzard. The gizzard grinds and
crushes food before passing it into the small intestine.
3.
Digestive Process
a. Food is broken down in the mouth (except birds), stomach (gizzard in birds), and
then passed into the small intestine, the primary site for the digestion and
absorption of carbohydrates, fats and proteins.
b. Undigested food passes from the small intestine into the large intestine where the
main activity is the absorption of water from the undigested food and addition of
lubricating mucus to aid in passage of waste.
4.
Digestive systems of FISH vary somewhat.
a. Type of feed fish eat is largely determined by the type of teeth they have.
b. Some fish swallow prey whole while others chew up their food.
G. Reproduction in small animals
1. Sexual Reproduction is the union of egg and sperm to produce a new animal
a. Two parents required: male furnishes sperm (spermatozoa or male animal sex
cell) and female supplies egg or ovum (female sex cell).
b. Natural insemination - process of male depositing semen into female
reproductive tract.
2. Sexual terminology
a. Conception creation of new life by the fertilization of an egg.
b. Estrus is the heat period when female is receptive to male and will stand for
mating.
c. Fertilization is the union of the egg and sperm
d. Gestation – period of pregnancy - begins with conception and ends with
parturition
e. Ovulation- releasing an egg for fertilization.
f. Parturition- process of giving birth to young
g. Pregnant- Stage of baby development in reproductive tract
3. Female reproductive anatomy
a. Ovary- primary reproductive organ produces the egg (female gamete)
b. Gamete- sex cell that unites with other sex cells
c. Embryo (developing young) goes to the uterus in mammals after 3 – 5 days.
d. Uterus - The place of embryo growth and development.
e. The cervix is the part of the uterus that contains rings and cervical mucus to seal
the uterus to keep out contaminants during pregnancy.
f. The vagina is the reproduction passageway and place of urine excretion.
g. The vulva is external opening to the reproductive tract.
4. Male reproductive anatomy
a. Testicle- primary reproductive organ and produces the male gametes sperm
b. Two testicles are held externally in the scrotum or sac that helps control the
temperature so that the testicles remain cooler than the body.
c. Sheath- A fold of skin that is a protective covering for penis.
5. Gestation or the time from conception to birth (parturition) varies for each species.
Species
Cats
Dogs
Rabbits
Hamsters
Gerbils
Rats
Mice
Guinea pigs
Ferrets
Gestation Period
51 - 65 days
56 - 70 days
30 - 32 days
16 days
24 - 26 days
21 – 24 days
21 – 24 days
56 – 74 days
42
days
6. General Characteristics of gestation
a. Gestation is usually identified by an increase in the female’s breast and abdominal
size, weight, and appetite at various stages of the gestational period.
b. Restlessness is a usual sign that the gestation period is coming to an end and
parturition (birthing) is about to take place.
c. A nesting box of straw, shavings, paper, etc. may be provided for pocket pets and
rabbits. Care should be taken not to excite animals at birthing as most do not
need assistance.
d. Dogs and cats should be given a birthing box in a quiet location one to three weeks
prior to parturition so that they may get comfortable with the setting.
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Body System Structure
A. Organisms begin as a single cell created from the fertilized ovum.
B. As cells divide and grow they differentiate into various tissues and serve various
functions in the body.
C. There are essentially 5 tissues found in the body:
1. Muscle- contractile tissue that allows for movement of the animal.
2. Connective- holds various tissues together such as bone.
3. Nerve- tissue that transmits information to various parts of the body.
4. Epithelial- tissue that covers other tissue such as skin.
5. Fluid- liquid type tissue such as blood.
D. The tissues work together to form the organs that sustain life and serve various
functions.
E. Each body system will have a variety of the different tissues with each depending
on the other to function normally.
Skeletal System Anatomy
A. Functions- protect vital body organs and give form or shape to body.
B. Major parts include bones, cartilage, teeth and joints.
C. Kinds of Bone- based on the different structure of the bone.
1. Cancellous Bone- also known as spongy bone. Soft bone tissue filled with
holes that are surrounded by hard bone. Typically found at the end of long
bones.
2. Compact Bone- consists of a structure known as the Haversian system.
This system is a hard, protective layer of bone tissue that surrounds bone
marrow.
D. Types of Bone- classified based on the shape or structure of the bone.
1. Long- long cylindrical shaped bones that support the body. Example:
femur.
2. Short- cube shaped bones. Example: carpus/knee.
3. Flat- long, wide bones that protect vital organs. Example: scapula.
4. Pnuematic- contains sinuses (spaces) that come into contact with
atmosphere. Example: face bones.
5. Irregular- various shapes that protect and support the nervous system.
Example: vertebrae.
6. Sesamoid- flat and round shaped bones. Located along tendons.
Example: patella.
E. Components to the Skeletal System
Note to Teacher: Use a skeletal diagram from the “Modern Livestock and Poultry”
textbook or from the Internet to illustrate the major bones of the animal.
1. Axial Skeleton- bones that are on or close to the midline of the animal.
Major bones of the axial skeleton:
i. Vertebral Column- includes 5 sections.
a. Cervical vertebrae- section closest to the skull.
b. Thoracic vertebrae.
c. Lumbar vertebrae.
d. Sacral vertebrae.
e. Coccygeal vertebrae- tail section.
ii. Ribs.
iii. Sternum- breastbone.
iv. Skull.
2. Appendicular Skeleton- bones that project from midline of the animal.
i. Pectoral Limb- front limb of the animal. Major bones of pectoral
limb:
a. Scapula- shoulder blade.
b. Humerus- arm.
c. Radius and ulna- forearm.
d. Carpals- knees of the forelimb.
e. Metacarpals- feet/hoof.
f. Phalanges- toes.
ii. PelvicLimb- hind limb of the animal. Major bones of pelvic limb:
a. Femur- upper leg bone.
b. Tibia and fibula- lower leg bones.
c. Tarsals- hocks.
d. Metatarsals- feet/hoof.
e. Phalanges- toes.
Muscular System Anatomy
A. Functions- provide movement, form and generate heat for animals. Also
important in the support of life through the digestive and respiratory systems.
B. Lean portion of the carcass of meat animals used for human food.
C. Classes of Muscles
1. Voluntary- under control of the animals will.
2. Involuntary- not under control of the animals will.
D. Types of Muscle
1. Striated- voluntary and involuntary muscles that are attached to the
skeleton by tendons.
i. Also known as skeletal muscle.
ii. Most meat consumed by humans is striated muscle tissue.
iii. Makes up majority of muscle tissue in body.
2. Smooth- involuntary muscle found in internal organs and blood vessels.
i. Acts more slowly than other muscle types.
ii. Can react to stimuli other than nerve endings such as chemicals
and/or hormones.
3. Cardiac- involuntary muscle found in the heart.
Respiratory System Anatomy
A. Functions- provide oxygen to tissues and removal of carbon dioxide, control
temperature and voice production (“talking-” squealing, mooing, etc.)
B. Major Organs Include
1. Nostrils- draw in air.
2. Nasal cavity- air is warmed and moistened while dust particles are filtered
out. Also responsible for smell.
3. Pharynx- site where air and food passages are joined and split into
respective parts.
4. Larynx- cartilage structures that contain vocal cords.
5. Trachea- tube that connects larynx to bronchi.
6. Bronchi- two branch shaped structures that connect trachea to each lung.
7. Bronchioles- smaller branches inside lungs.
8. Alveoli-thin microscopic sacs located at the terminal end to respiratory
system. Location of actual carbon dioxide and oxygen exchange.
9. Lungs- large lobed organs that contain parts essential for oxygen
exchange. Spongy, pinkish colored organ located between the front legs
of the animal and extends to the abdominal area.
10. Diaphragm- large muscle separating the chest from the abdomen and aids
in the respiration process.
Circulatory System Anatomy
A. Functions- supply body tissues with nourishment, collect waste materials from
body tissues, transports hormones and cells of the immune system.
B. Major Organs/Parts Include
1. Heart- major involuntary muscle that pumps blood throughout the
circulatory system. Large reddish colored organ located just behind the
shoulder on the left side of the animal.
2. Arteries- small tube-like structures that carry blood from the heart to
organs and tissues throughout the body.
3. Veins- small tube-like structures that carry blood to the heart from organs
and tissues.
4. Capillaries- vessels that exchange nutrients, oxygen, carbon dioxide,
waste products, etc. from the arteries and/or veins.
5. Lymphatic System- works with circulatory system to carry lymph fluid from
vessels and glands to the capillaries that feed into the circulatory system.
Nervous System Anatomy
A. Functions- coordinate the physical movement of the body, respond to hearing,
sight, smell, taste, and touch and react to internal and external stimuli.
B. Major Parts/Organs Include
1. Central Nervous System- functions to coordinate and control body
activities. Includes the brain and spinal cord.
2. Peripheral Nervous System- includes all the nerves that send messages
to and from the central nervous system. Two basic types of nerves:
i. Somatic Nerves- voluntary process of relaying information between
skin, skeletal muscles and the central nervous system. Reflexes
are also somatic nerves, but are controlled involuntarily.
ii. Autonomic Nerves- involuntary process of relaying information from
central nervous system to organs.
Endocrine System Anatomy
A. Function- works with the nervous system to control internal body functions.
Affects and controls growth, reproductive functions (heat, lactation, birth, etc.),
shape of the animal’s body, feed efficiency and adaptation to environment.
Hormones are primary substance involved in function of endocrine system.
B. Major Organs/Parts Include
1. Pituitary Gland- major gland of the endocrine system. Secretes hormones
that regulate the other hormones involved in the endocrine system.
2. Ovaries- secrete hormones such as estrogen and progesterone that are
involved in the estrus cycle, gestation and parturition.
3. Testicles- secrete hormones such as testosterone that are involved in the
production of sperm, sex drive and development of male body
characteristics.
4. Thyroid Gland- secretes the hormone thyroxin that stimulates growth and
metabolism.
5. Hypothalamus- secretes hormones involved in the reproductive cycle.
6. Adrenal Glands- secrete hormones such as adrenaline that respond to
stress.
Urinary System Anatomy
A. Functions- filter fluid and remove waste.
B. Major Organs/Parts Include
1. Kidneys- blood passes through and waste products and water are
removed. Urine is the combination of this liquid and waste products.
2. Ureters- the liquid (urine) from the kidneys travel through tube-like
structures called ureters to the bladder.
3. Bladder- stores urine.
4. Urethra- tube-like structure that excretes the urine waste.
C. Poultry do not have a bladder or urethra. The ureters are directly connected to
the cloaca where solid and liquid wastes are excreted.
Digestive Terminology
A. Digestion- the process of breaking feed down into simple substances that can be
absorbed by the body.
B. Digestive System- the parts of the body involved in chewing and digesting feed.
C. Absorption- the process of taking digested parts of feed into the bloodstream.
D. Ruminants- animal that have a stomach that is divided into several parts.
1. Cattle, goats and sheep are examples of ruminant animals.
2. Ruminant animals can digest larger amounts of roughage material compared
to nonruminants.
3. Ruminants do not chew their food completely. Some food is swallowed and
then rechewed later through a process known as “chewing the cud.” This
process is also called rumination.
E. Nonruminant- animals that have a monogastric or single compartment stomach.
1. Horses, pigs, dogs, cats, and poultry are examples of monogastric animals.
2. Non-ruminants cannot eat and digest as much roughage as ruminants.
Nonruminant Digestive System Parts and Functions
A. Mouth
1. Function: Bites and chews food. Breaks food into smaller particles. Saliva
present in mouth contains enzymes which speed up the digestive process.
2. Description: Beginning of digestive tract. Includes teeth and tongue.
B. Esophagus
1. Function: Guides food from mouth to stomach with involuntary muscular
contractions.
2. Description: Pinkish grey colored muscular tube next to trachea. Guides food
from mouth to the stomach.
C. Stomach
1. Function: Enzymes act on feed, churns, and mixes feed.
2. Description: A “U” shaped pinkish/white colored sac connected to the
esophagus.
D. Small Intestine
1. Function: Partially digested feed is mixed with bile, pancreatic juice and
intestinal juice. Most food nutrients are absorbed from the villi (small
hairlike projections) in the small intestine.
2. Description: Long coiled tube.
E. Cecum
1. Function: Serves little to no function for most animals. Horses, rabbits and
guinea pigs have an enlarged cecum that uses microbial action to break down
roughages.
2. Description: A blind pouch located between small and large intestine.
F. Large Intestine
1. Function: Absorbs water and adds mucus to the undigested feed to form
feces.
2. Description: Coiled tube shorter in length, but larger in diameter than the
small intestine.
G. Anus
1. Function: Excrete waste.
2. Description: End of digestive tract.
Ruminant and Nonruminant Digestive System Accessory Organs
A. Liver
1. Function: Produces bile that acts on fats.
2. Description: Dark brown structure made of several lobes. Largest gland in
the body, located under the stomach.
B. Pancreas
1. Function: Produces digestive enzymes.
2. Description: Elongated reddish colored organ that lies against the stomach.
C. Gall Bladder
1. Function: Produces bile that aids in digestive process.
2. Description: Sac like structure filled with greenish fluid. Located on the liver.
Poultry Digestive System Parts and Functions
A. Mouth
1. Function: Pecks and takes in feed. Poultry do not have teeth.
2. Description: Yellow pointed structure.
B. Esophagus
1. Function: Guides food from beak to crop.
2. Description: Muscular tube shaped structure.
C. Crop
1. Function: Stores and softens feed from saliva secretions.
2. Description: Oval sac-like structure between esophagus and proventriculus.
D. Proventriculus
1. Function: True stomach of chicken, but serves no true function.
2. Description: A wider section of the digestive system compared to esophagus.
E. Gizzard
1. Function: Feed is crushed and mixed with digestive juices. Contains grit and
gravel to assist in crushing feed particles.
2. Description: Oval shaped muscular that is purplish in color. Located
between the proventriculus and small intestine.
F. Liver
1. Function: Accessory organ that produces bile that acts on fats.
2. Description: Dark red colored organ made up of several lobes.
G. Small Intestine
1. Function: Mixes juices, most food nutrient absorption occurs in small
intestine.
2. Description: Long tube like structure.
H. Ceca
1. Function: Contain soft, undigested feed, but function is unknown.
2. Description: Unlike other animals, poultry have two ceca. Located between
small and large intestine and are “blind” pouches, each are approximately 7
inches in length.
I. Large Intestine
1. Function: Absorbs water and adds mucus to undigested feed, which becomes
feces.
2. Description: Tube-like structure large in diameter when compared to small
intestine. Filled with digested feed.
J. Cloaca
1. Function: Digestive and reproductive tracts combine and prepare for
excretion of waste or eggs.
2. Description: Enlarged part of digestive tract located just before the vent.
K. Vent
1. Function: Excrete solid (feces) and liquid (urine) waste.
2. Description: External opening and the end of the digestive tract.
Reproductive Management Terminology and Traits
A. Castration- removing the testicles of male animals to prevent breeding.
B. Colostrum- the first milk produced after a mammal gives birth that contains
antibodies needed for immunity.
C. Estrus- the time a female animal is receptive to be bred, also called heat.
D. Estrus Cycle- the length of a female’s cycle from one estrus to the next.
E. Gestation- the time an animal is pregnant.
F. Puberty- age at which animals reach sexual maturity and begin come into heat.
G. Lactation- the period of time that milk is secreted by the mammary glands.
H. Parturition- the act of giving birth by female mammals.
I. Ovulation- the release of the egg cell from the ovary.
J. Fertilization- the union of the sperm and the egg cells.
Parts & Functions of the Female Livestock Reproductive System
A. Ovaries
1. Function: Produce ova called eggs.
2. Description: Two oval shaped organs located near the end of the
reproductive tract inside the body cavity.
B. Oviducts
1. Function: Carry the eggs from the ovaries to the uterus. Also called fallopian
tubes.
2. Description: Small tubes that are near but not attached to ovaries and have a
funnel-shaped end near the ovary.
C. Infundibulum
1. Function: Picks up eggs at ovulation and directs eggs into the oviduct.
2. Description: Funnel-shaped end of each oviduct near the ovary.
D. Uterus
1. Function: Also called womb, place where fetus grows and develops.
2. Description: Organ with two branched horn-shaped attachments called
uterine horns. Will have a baby inside if animal is pregnant.
E. Cervix
1. Function: Serves as a passageway for sperm to travel from the vagina to the
uterus. Also seals the uterus during pregnancy to prevent pathogens from
affecting fetus.
2. Description: Thick walled structure made up of folds and rings of muscular
tissue. Located at the neck of uterus. Separates the uterus from the vagina.
F. Vagina
1. Function: Receives the male penis and sperm at breeding. Also serves as a
passageway for the baby to pass through at birth and is a passageway for
urine to be expelled.
2. Description: Connects the vulva to the cervix.
G. Vulva
1. Function: External opening to female reproductive and urinary systems.
2. Description: External opening made up of folds of skin.
Livestock and Poultry Male Reproductive Parts
A. Scrotum
1. Function: Holds and protects testicles.
2. Description: Saclike part outside livestock that holds testicles.
B. Testes or Testicles
1. Function: Produce sperm and male sex hormones.
2. Description: Two oval meaty type structures inside scrotum in livestock and
inside body cavity of poultry on each side of backbone.
C. Epididymis
1. Function: Stores sperm while they mature.
2. Description: Long coiled tube connected to each testicle.
D. Vas Deferens
1. Function: Serves as a passageway for sperm to travel from the epididymis to
the urethra.
2. Description: Tube that connects the epididymis to urethra.
E. Seminal Vesicles
1. Function: Produce a fluid that protects and transports sperm.
2. Description: A gland that opens into urethra.
F. Prostate Gland
1. Function: Produces a fluid that is mixed with the seminal fluid.
2. Description: Gland near the urethra and bladder.
G. Cowper’s Gland
1. Function: Produces a fluid that moves down the urethra ahead of the seminal
fluid. It cleans and neutralizes the urethra to protect the sperm.
2. Description: A gland near the urethra.
H. Penis
1. Function: Deposits semen in female animals. Papilla serves this function in
poultry
2. Description: Rod like tissue covered by sheath.
I. Sheath
1. Function: Protects penis from injury.
2. Description: Skin that covers the penis.
Parturition of Animals
A. If an ovum of the female animal is fertilized and the animal becomes pregnant, the
embryo begins to grow and develop.
B. After a period of embryological development, the developing animal is referred to as
a fetus.
C. During gestation, the fetus develops in the uterus.
D. At the end of the gestations period, parturition begins.
E. Any presentation (position at birth) that is abnormal and could cause problems as
severe as death of the newborn animal and/or the mother.
F. Parturition Process
1. Begins when increased estrogen causes the uterus muscles to contract.
2. First water bag appears, enlarges and breaks open.
3. Soon afterwards, the second water bag containing the fetus breaks open and
the presentation of the offspring begins.
4. Several hours later, the placenta and other membranes (afterbirth) are
expelled. If afterbirth is not expelled, the animal will become sick.