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avian
11/4
Virginia Pierce VMD

anatomy and physiology

consider these things when treating birds

pet bird practice is 
lucrative. if you know exotics, you can pay off your loans. you need to 
know this: what does normal look like? what does normal act like? know 
husbandry and nutrition - these are more and more important the smaller 
and smaller the thing gets, and the higher its metabolic rate gets 
(leaves you less margin for error). the best way to learn about normal is 
to check out bird clubs and watch normal birds.

she's trying to shock us 
now - understand that chickens are not birds. they started as birds, but 
they are no longer real birds. we have bred and bred them, and now they 
are egg and meat machines. you can know all there is to know about 
chickens and this will be useless information when it comes to caged 
birds. 

who wants to treat a mouse like a cat? anyone? so, same thing 
applies - you can't treat a parrot like a chicken. first page of handout 
has thousands of spp listed. many kinds of birds and they are not 
chickens. many are not even galliformes, totally unrelated to chickens.


**
what is a bird? a living bird is defined by the one thing no other 
creature has - feathers. 
**only birds have feathers. 
also, **no living 
bird has teeth in the mouth, though some extinct ones did. teeth are 
dense, heavy objects used to crush food. they weigh too much for birds. 
if you want to fly, you shouldn't have your center of gravity in your 
mouth :)is that why there are no teeth? so birds can fly? who knows. you 
can't say for sure. we know they fly. we know they do not have teeth. 
that's a silly question. they fly and do not have teeth. causation 
unknown. they do have hard, keratinized beak structures, some of which 
have nasty serrated edges that can really hurt you. the functions that we 
do, that humans do, in our mouths, are prehending food, getting it in, 
chewing, and then actually starting to digest with salivary amylase. 

**birds have mucus type saliva to moisten food and help it down, but no 
salivary amylase. they do not have teeth so they don't do mechanical 
digestion there either. 
**birds have a crop - a storage chamber. they 
eat a lot, storing food in the crop, then slowly release food into the 
stomach. not all birds actually use the crop, but they all have one. 
things like ducks, geese, pigeons - they fill the crops with seeds. if 
you eat fish or nectar, you don't really need to use this storage area, 
so those birds don't really use them. 
**birds have stomachs split into 
two parts. think of turkey/chicken/duck gizzards. those birds eat a lot 
of seeds. the gizzard has a thick lining and really thick muscles to 
replace the teeth. that's what that part of the stomach is for. those 
birds also eat some stones, to help grind up the food. the glandular part 
of stomach, aka proventriculus, is before the mechanical ventriculus aka 
gizzard. now, not all birds have big muscular gizzards. nectar feeders or 
fish feeders or meat eaters have simple stomachs, just like us. it takes 
no effort to digest these things. so, birds do not all have the gizzard. 

**other animals can have beaks. nothing else has feathers. turtles have 
beaks with no teeth, so the beak does not define the bird. 
** birds have 
scales on legs and feet like reptiles. not defininng though. the one 
defining characteristic is feathers.
** skeletal features shared with 
reptiles - among these are ******* quiz point ***** how many occipital 
condyles do mammals have? they are those two big round things on the back 
of the skull that articulate with the first vertebra. birds and reptiles 
only have one **** that makes their heads way more mobile than ours. we 
can't turn our heads more than 190 or so. birds can go much closer to all 
the way around.   the other really cool thing birds share with reptiles 
is processes on their ribs - a little projection from one rib going back 
to the next one - this not solidifies, but rather strengthens the rib 
cage. these are the uncinate processes. another thing birds share with 
reptiles. 
** back to feathers, which define birds - they afford 
insulation, which is why your down jacket keeps you so warm. down 
feathers trap air, creating an air layer b/w skin and outer feathers. the 
outer feathers keep bird waterproof. * so warmth and waterproofing are 
feather functions **this is partly due to oils put on during preening, 
but mostly due to 3D structure of the feather. remember back to chemistry 
we talked of water and the properties of water - one of those is surface 
tension. water molecules hold on to eachother so you can float stuff on 
there b/c of surface tension. feather structure and surface tension of 
water is why water stays off bird. ** other function is flight. powered 
flight, not just gliding flight. bats, the flighted mammal, also have 
powered flight, using big skin flaps as wings. some snakes can fly, as 
can some squirrels although that is gliding flight. the other things 
feathers do is ** communicate. either camouflage, or display. think about 
color of birds. even if you have never seen things other than robin, 
cardinal...they must see color. they come in so many colors! often there 
are flashy, colorful male birds and really drab plain females. the 
redwing blackbird has flashy red shoulder epaulets he can flash at you. 
females are brown, drab, plain, totally different looking. peacocks - 
males have those big irridescent tail fans (well, not really the tail, 
but whatever), and females just have a brown body, with a little bit of a 
topknot, and a bit of color on the neck. btw male peacocks do roost up in 
trees and can fly. 

slides:

the eye of a bird - this is a drawing. 
she's trying to emphasize the point. there is a cuban hummingbird in 
front of the eye. the eye is the eye of the ostrich. the hummingbird is 
about the same size as the diameter of the ostrich eye!

there are some 
penguins that are almost as tall as people...ostriches, emus are tall. 
some extinct island spp were really tall

a pelican has about a 12 foot 
wingspan; pterodactyls had 26 foot spans (not birds, btw - not dinosaurs 
either). so birds have different body heights and very different body 
shapes. there is a lot of variety, is the point being made.
some birds 
have special features - long fancy tails, outrageous beak of toucan, the 
helmet-feathers of some other bird.

wings have different shapes. you 
think about feet being different - 5 digits is primitive, nonspecialized; 
more specialized you get the fewer digits you have. if you are 
specialized for running like horses, you lose 4 digits and have only the 
3rd remaining. cows have the 3rd and 4th (all the bovids). birds have 
different shaped wings depending what they do.
albatross, to glide over 
the ocean for almost your whole life, you do not want to flap all the 
time, so you have really long, long wings like on airplane gliders.
hawks 
have fat, broad wings for soaring
falcons have short, pointy wings for 
maneuverability and speed

so you need to know - how long a tail shoudl 
that bird have? is it missing tailfeathers or is it supposed to be short?


**birds are coverd with feathers - true or false? false. they occur in 
tracts. if you have hair, you have it everywhere unless you have 
follicular dysplasia or aplasia. but feathers occur in tracts. there are 
different areas with different feather types. on wings - primary feathers 
= flight feathers, coming off the ulna. in mammals, the ulna is reduced. 
think of hooved animals - almost all that is left of ulna is olecranon, 
and radius is main support bone. in birds, ulna is more important and 
flight feathers come off it. 
birds have a lot of fused bones - in 
skulls, wrists, legs, feet, vertebral columns, pelvis. one thing that 
does is decrease the # of movable joints. also strengthens skeleton in 
other ways. feathers come from follicles just like hair does. they have 
blood vessels to nourish them. they are covered in a sheath, they emerge 
from sheath, powdery stuff comes off.

there are different types of 
feathers - flight feathers, fancy feathers for decoration, down feathers, 
ventral covering feathers

there is a quill, the calamus, which is the 
"stem" of the feather, the part you can hold as a pen, that connects to 
the bird. there is a hole at the bottom where the blood vessels went in 
during development. then there is the whole web of the feather on the 
sides of the quill. you know how you can sort of unzip it and zip it back 
up? they have sort of a velcro effect. this is critical for the birds 
-that's why they preen. they need the feathers smooth, mechanically in 
very good condition. they have to be all smooth. otherwise they can't fly 
right, aren't waterproof, won't stay warm. the web of the feather is made 
of barbs which have barbules coming off at 90 angles. there are tiny 
little hooks on the barbules. this is how the feathers stay attached to 
eachother and how the barbs stay together. this 3D surface that forms by 
hooks, hamulets, and barbules, together with water surface tension, are 
what makes it water repellent. it's all physics.

birds molt. they drop 
feathers, grow new ones - because damage occurs.  they molt in particular 
patterns, not all at once. if you break off some of the barbules feathers 
aren't properly smooth. you end up with a bird who doesn't look right, 
with sort of ruffled feathers. 

baby bird - we see naked skin, and new 
feathers erupting on tracts. this is normal for a baby. sometimes, birds 
lose their feathers and you can see them breathing b/c the airsac is 
usually covered with feathers but you can see it when the feathers are 
gone. 

living birds do not have teeth in their mouths, remember? this 
baby has a little thing on his upper beak - an "egg tooth" - a calcarious 
knob, sort of pointy. bird has hatching muscles in back of the neck, and 
an egg tooth. it uses this to crack open the shell of the egg and get it 
open. this can take hours. hatching is difficult. (but it sure beats 
labor!) anyway, the egg tooth isn't a real tooth. 

birds of paradise - 
have these long whiskery things that are actually feathers.
crown on 
african crowned crane are also feathers
if you look at a bird that is at 
least one season old, so it has already gone through nestling 
stage...it's adult size with adult plumage - you can't stage the age 
after that. if you *had* to you could look in horse mouth and say how old 
it is. but you can *not* do that with birds. after a year, that's it. you 
can't tell. *but* in some spp plumage gives them away - year 1, brown. 
gradually get more and more grey until adults have sharp black/grey/white 
appearance. this takes 3-4 yrs. so if you see gulls that are all 
different spp, they are probably all different ages. also bald eagles - 
adults have white head/tail, young are all brown. white takes about 5 
years to gradually show up. but otherwise you can't age birds.

birds 
have cool beaks. these rae what they use to prehend food. many shapes of 
beaks exist. that makes sense. they eat different things. mammals have 
different tooth shapes for that. 
puffins have a beak that molts, and in 
nonbreeding season beak is dull, in breeding season, cheek feathers get 
all white and beak gets blue, orange, red, yellow stripes. 
fish eating 
duck - many serrated ridges on this bird beak. that's to help hold 
slippery wriggly fish.  the ridges all point caudally.
pelican - has a 
big skin pouch ventral to the beak. pelicans take a big mouthful of water 
and fish, squeeze water out, then swallow the fish. 
spoonbill - long 
spoon shaped beak
flamingoes - go in shallows of marine areas, stir 
things up with beak, then pick up tiny crustaceans and eat those. 

skimmer - lower beak longer than upper beak. that's normal for them. they 
fly right above the water with lower beak in water, picking up tiny fish. 

woodpecker has a big chisel type beak
nectar eaters have long, needle 
like beaks. 
toucan - beak mainly decorative. picks up fruit with tip of 
beak, tosses it back. beak is light, hollow, decorative. but there is a 
very serrated edge, they can really hurt your finger.
hornbill - looks 
like a solid, bony beak but of course no, it is very light. the whole 
cask (?) is hollow. eats lizards, fruits - beak mostly decorative.
small 
triangle beak like finch, cardinal - very strong, for eating seeds.


birds live in different places - can guess by looking at feet. 
webbed 
feet- water birds. 
few toes - ostrich (only 2 toes) - as in horse/cow, 
they run for locomotion.
strong toes, heavy claws - predator who catches 
prey with feet. osprey has ridges on feet to hold slimy slippery fish


very long toes, narrow, skinny - lily hopper - walks on lily pads - about 
a foot tall, these birds - but feet act like snowshoes, to distribute th 
weight of the bird. 

four toes with two pointing anterior and two 
posterior - woodpecker, parrot - total coincidence there - but this is 
because they use their feet to climb.

[she wants to know if there is a 
problem b/c people are talking. yes, the problem is that it is 1:55]

at 
base of tail, there is a gland - now, birds have few glands, because skin 
is very thin, but they have this uropygeal gland, named after the area 
where you find it. also called "preen gland" - it's this little bump 
within which they make their feather oil.  

zoonoses: there are 
infectious disease people can get from birds. unlike in mammals, there 
are very few in birds to worry about. one is chlamydia psittaci - 
psittacosis - a disease of parrots. more properly called ornithosis or 
chlamydiosis, since it does affect more than psittacines. turtle doves 
can be carriers and not get sick. it can actually kill people, but you 
have to not be careful. i mean, rabies can kill  you too. but if you are 
careful you will not get it. chlamydiosis isn't usually that bad. if you 
wear mask/gloves with a bird you suspect may have chlamydia, you reduce 
your risk dramatically. signs are flulike if you get it, very nasty if 
you get bad case. very easy to treat but an MD will not think of it, 
he'll tell you you have the flu. meanwhile, your lungs are filling up. 
store in your mind the kinds of diseases you as a vet are exposed to! you 
need to know what disease you might get, or your clients might get. you 
may have to consult with the client's MD. if you wash hands, wear gloves 
and mask - you reduce risk of dz. 

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anat/phys

birds have 
the same tissues as mammals and the tissues respond to insult in the same 
way. if you know your basic stuff, just add basic bird things in like 
there are different blood cells, etc.

unlike necropsy in horse, you 
don't need much equipment to do bird necropsy (fork and knife?). 
hemostats, scissors, scalpel, ruler, chicken shears, syringe to get 
fluid, culturette to culture things, slides, forceps. 

cytology is going 
to give a lot of quick information, cheaply. you should always get as 
much cytology experience as possible. you can take biopsies til the cows 
come home, but you get the results back in two weeks so it isn't as 
immediately useful. you also need gloves/mask, by the way, doing bird 
necropsy.

if you are looking at a live bird, you have to weigh it. keep 
track of your avian patients' weights. this is a good indication of 
health status. sudden weight changes or gradual weight changes can 
indicate problems. 

PE: feel the bird. elbows are supposed to be bumpy. 
know how much joint laxity to expect. you need to know what normal birds 
feel like, where bony projections should and should not be. learn to use 
your hands to feel these things. hands are great diagnostic tools. how do 
you check for dehydration in a bird? tent test in mammals, right? well, 
in a bird you can't do that. you can look at their eyes and see if they 
are sunken in. see if ruffled feathers.

assess nutrition status. 
pectoral muscles should be big, those are flight muscles. when you 
palpate, how much muscle is there? is it plump? if not eating well maybe 
it is thin, atrophied, the keel will be more and more prominent. remember 
the keel is part of the sternum. if you can put your finger on both sides 
of keel and feel keel, you will know that bird has lost a lot of muscle 
mass. 

try to do necropsies on all your patients that die. you need 
permission. but you want to always confirm what your fingers, eyes, and 
ears told you. once the animal is dead, you can really open them up and 
see what's wrong. you get to find out. that's the cool thing about 
pathology. on the slide - the white bumps on the skin we see are the 
feather follicles - the inside of the follicles. the area where there is 
no bumpiness is where there is no feathering. 

note the yellow color of 
the inside of skin - this isn't jaundice, this is influenced by diet. 
birds deposit fat not everywhere under skin, but at stifles, edge of 
sternum, and up at thoracic inlet. distribution of fat bodies is not 
mammalian. 

we have three layers of muscle covering our viscera. birds 
have very thin abdominal muscles - you can see through them. the sternum 
goes far more caudal, to offer more protection. the dark purple thing 
poking out from under sternum on the right side is the liver, the right 
lobe in birds is normally bigger than left - but it is not supposed to 
peek out from under sternum - this one is enlarged.

this bird is fat. 
there are huge fat pads in the fat locations, and note we see no liver 
sticking out. this was a healthy bird that got into an oil spill. 

this 
bird is too skinny. we see diamond shaped areas where feather follicles 
are - pink color is from the muscles that move each feather 
independently. that's how those blackbirds move feathers to show 
epaulets, or how birds show their crests, or puff themselves up when cold 
or sick. this bird has no pectoral muscle left, to speak of. keel very 
prominent.

next step is to remove the chest wall - you need shears or 
something. in there you see heart, liver - note difference in shape and 
size b/w the two liver lobes (not on quiz!)the liver should stop way up 
inside the body cavity. livers are supposed to be that brown livery color 
you expect it to be. caudal to liver we see gizard - muscular parts 
obvious. we see intestines that look like intestines, and pancreas that 
looks like pancreas,  nice and pink. 

up in chest, we see heart, great 
vessels coming off, the thyroids up with the carotid arteries, down in 
the cavity caudal to thoracic outlet.

birds have complete tracheal 
rings, unlike mammals. these can't collapse.
if you take heart away from 
aorta, and take stomach and intestines out, you are left with dorsally 
situated organs. you have lungs, kidneys, ovaries, and body wall. bird 
lungs are not like ours. they do not expand and contract. RO Davies tells 
you all about mammalian lungs. avian lungs are more like sponges, lots of 
holes, bronchi, parabronchi...in mammals, think back now, blood flow in 
lungs is countercurrent to air flow. old blood comes in, flows past new 
air. you are maximizing gas diffusion. but the best you can get is 50-50, 
the same concentration on opposite sides. that is why we pass low O2 
blood next to High O2 air. birds have cross current ventilation. air flow 
and blood flow are perpendicular. in birds, this is more mechanically 
efficient. it allows more complete - blood constantly contacts new air? 
birds have high metabolic rates. airflow in mammalian lungs is 2 
directional - comes in mouth/nose, enters lungs, comes back out same way. 
so there is dead space- there is some air that doesn't leave. there is 
only so much turnover. in birds, there are added features. there are air 
sacs. these are sometimes potential spaces, sometimes air filled. air 
comes in one breath, right through lungs, into sacs, in abdominal cavity. 
next breath that comes in goes to air sacs, pushes that air sac air into 
the lungs. third breath then goes straight to air sacs, pushing first 
breath out. so there is no constant CO2 buildup. air flows in 
unidirectional loop. airsacs have very thin walls, no blood vessels. no 
gas exchange/respiration here. all gas exchange occurs in the fixed 
volume lungs. 

mammals have a larynx. birds have a syrinx. this is down 
at the bifurcation of trachea. a bird that sings has a fancy one with 
many membranes. it's a resonating chamber. so these membranes vibrate 
like vocal cords do. 

bony cortices are very thin. you can repair 
fractures, but realize these cortexes are very very thin, and the bony 
trabeculae within the lumen are what strengthen the bone and solidify it. 


adaptation to flight - hollow bones. we don't know if they got the bones 
so they could fly. but they have these bones that are hollow, and they 
fly.

fused pelvic bones, fused vertebrae - joints at t10, and at neck. 
birds have variable numbers of cervical vertebrae.
birds have cool eyes. 
one thing about them is there is a bone - a ring of bones around the eye, 
the scleral ossicles. these keep the globe shape intact. also they have 
projection from the retina into the vitreous humor called the pectin. no 
one knows what that is. it is very vascular, may nourish structures 
inside eye. also, it may leave shadows on the retina. eyes are designed 
to percieve edges and movements. our eyes do the same thing. detection of 
movement and edges happens in the eye, not the brain. but so, this thing 
may cast shadows, magnifying the movements in front of the eye, so they 
are more easily detected. 

bird does have a four chambered heart. 2 
atria, 2 ventricles. pulmonary circulation. systemic circulation. like 
mammals. one cool thing birds have is right AV valve is muscular flap, a 
shelf - it closes off atrium/ventricle. on the left, there are the same 
leaflets and stuff we have. left ventricle is very thick and muscular. in 
this heart we see a glob of caseous white stuff on valve leaflet - 
vegetative valvular endocarditis.

GI tract - esophagus, proventriculus, 
gizzard, duodenum, pancreas - pancreas is in the same place in every 
vertebrate - always associated with the duodenum. small intestine, large 
intestine - birds have paired ceca! we have a tiny cecum, and a tiny 
appendix. horses have a big cecum. birds have two long narrow ceca. they 
are blind ended pouches. the length of cecum relates to diet of bird. if 
bird eats mostly plant material that vertebrates can't digest, they will 
have long ceca in which bacteria digest the plant material.  in a 
chicken, you cut the cecum, and look for heterachus ?? what? 

meckel's 
diverticulum - an embryological remnant. remember the yolk? the yolk is 
outside the embryo, as it uses up food, yolk gets smaller, eventually 
pulled into the body and covered over. the little bump where yolk was 
attached to the intestine is meckel's diverticulum. 

birds that eat 
nectar - lorikeet - tip of tongue is like a paintbrush - they lap up the 
nectar. this tongue fringe increases surface area of tongue.

inside of 
gizzard - glandular proventriculus is obviously different from the 
muscular, keratinized part of gizzard. brown spots are ulcers - stress, 
infection, etc. 

weird white stuff - bird kidneys do not act like 
humans. birds use uric acid as nitrogenous waste product. it's white, 
pasty. uric acid is almost insoluble in water. if your waste product is 
uric acid, your body is conserving water. fish, amphibians - ammonia is N 
waste product - need tons of water to rinse out of system since ammonia 
is so toxic. mammals can concentrate urine with loops of henle. birds 
don't have those. they have nephrons sort of scattered around, no 
concentrating system - don't need it. they use uric acid. but, they still 
need some water. if they get dehydrated, they can't get rid of uric acid 
and it forms crystals. gets deposited on serosal surfaces, joints. this 
is gout. can be visceral, renal, articular. if you have a mammal in ARF, 
and you give enough fluids, you can support it. if you support it til the 
basement cells regenerate, animal can survive. but uric acid crystals 
cause irreversible mechanical damage. you can survive on 20% liver 
function and even less kidney functino, but you need SOME function. when 
kidneys are giant bags of uric acid crystals, you can't fix that and bird 
is going to die. 
bird kidneys can also get cysts. 


testicles - can get 
300x bigger in spring in some birds. they breed in spring.
they get small 
in fall. can be white, orange, black. 
some birds have a phallus. mallard 
duck, has penis. ostriches, have penis. most birds do not.

female birds 
have generally one ovary. that's usually on the left. some birds - 
raptors, owls, hawks - do have two functional ovaries. occasionally a 
chicken will have two, or a right one only. but usually there is just one 
on the left. this is an alleged adaptation to decreasing body weight to 
promote flight.

eggs are different sizes and shapes. pointy ones may do 
better on cliffs to avoid falling. different shapes, sizes, etc. 
hummingbirds eggs are really really tiny.

ovary from silky chicken - we 
see many follicles in different stages of maturation. chickens can lay an 
egg a day. 

penguin - inside of egg - embryo, yolk, amnion - and we see 
connections b/w abdomen and yolk sac. 

here we see a remnant - cystic 
right oviduct. big swollen thing.

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