Avian anatomy and physiology

Avian Anatomy and
Physiology

Christine Fiorello, DVM, PhD, Dipl. ACZM
Some slides from Heather Wilson, DVM, Dipl. ABVP Avian


Integument
¾ 2 layers: Dermis and

epidermis
¾ Epidermis thin except for
certain areas
¾ Keratinization produces
special structures: beak,
nails, scales, feathers
¾ Lacks glands


Feathers-7 types
¾ Contour
ƒ wing & tail
(flight)
¾ Semiplume
¾ Down
ƒ fluffy, no
barbules
¾ Bristle
ƒ “eyelashes”
¾ Powder down
¾ Hypopenna

¾ Filoplume


Uropygial Gland
¾ “Preen gland”
¾ Bilobed holocrine gland
¾ Conditions feathers
¾ Not all species have one


Purpose of
Feathers

¾ Flight
¾ Courtship
¾ Defense
¾ Insulation
¾ Waterproofing


Contour
Feathers
¾ Rows (pterylae)

in most species
¾ Apteryla=featherless tracts
¾ Remiges=Wing
flight feathers
¾ Retrices=Tail
flight feathers

Primaries attach to metacarpals
Secondaries attach to ulna


Waterproofing
¾ Preen gland secretions

are not necessary
¾ Interlocking of feather
barbules creates
watertight barrier


Musculoskeletal
System
Notarium

Synsacrum
Coccygeal


Avian wings
¾ Unique structure
¾ Flight feathers

attached to ulna
and metacarpals
¾ Ulna > radius

Bat
Pterodactyl
Superman



Pectoral girdle


Clinical skeletal anatomy
¾ Spinal fractures

at juncture of
notarium and
synsacrum
¾ See with birds
who flew into a
window


Fractures
¾ Bones are more brittle

compared to mammals
¾ Bones heal more rapidly
ã 4 weeks

ắ Fibrocartilagenous healing

first
ã may not be visible
radiographically


Pectoral Muscle
¾ Highly vascularized

muscle
¾ IM injections here
are absorbed rapidly
¾ Nonflighted birds
have soft, “flabby”
pectoral muscles


Lower limbs
¾ Femur
¾ Tibiotarsus
¾ Tarsometatarsus
ƒ “Hock” is
tibiotarsaltarsometatarsal
joint


Feet
¾ Each digit has +1

phalanx
ƒ Digit one has 2

phalanges
ƒ Digit two has 3, etc

¾ Parrots are

zygodactylus
ƒ Digits 1 & 4 face back
ƒ Digits 2 & 3 face forward


Cardiovascular system
¾ 4 chambered

heart
¾ Encircled by
liver
¾ Right jugular
vein larger
than left
(which may be
absent)


Lymphatic System
¾ No lymph nodes
¾ Lymph vessels follow veins
¾ Lymph plexuses (rete)
¾ Bursa of

Fabricius

ƒ B-cells


Kidneys
¾ Adhered to

dorsal body
wall
¾ Retroperitoneal
¾ 3 lobes
¾ Excrete uric
acid and some
urine


Renal Portal System


Nervous System
¾ Brain: 3 meniges & 12 CN as in mammals
¾ In contrast, birds have no neocortex
¾ Surface of cerebrum almost smooth
¾ Olfactory bulb relatively small

Bird

Mammal


Bird Brain

Eyes
¾ Most birds have excellent vision
¾ More cones than rods (in general)
¾ No blind spot (no optic disk)
ƒ Pecten, unique to birds, provides nutrients
¾ Iris contains striated muscle--

can’t use atropine to dilate
ƒ Need curariform drugs