Avian Urogenital Flashcards
describe the location and structure of the kidneys in avians
- generally lie symmetrically in bony depressions of the synsacrum (renal fossae); not floating, more “fused” to synsacrum
- often referred to as triad: kidney, adrenal, gonad
- sciatic nerve runs right near, so if kidney swells can compress sciatic nerve and get unilateral lameness due to kidney cause!
- tri-lobed in most birds
-13-17 lobules separated by interlobular veins in each lobe, cortical tissue predominates
-VERY MUCH FEWER nephrons than mammals (less crowded infrastructure) - avian kidney is larger than mammalian kidneys of similar body sizes (1.5-2.5% BW avian compared to 0.05% BW in mammals)
describe the radiographic appearance of the avian kidneys
- attached to the ventral side of the pelvis
- inflated airsac around the tissues provides negative contrast
- sometimes gonads are visible; depends on age, sexual maturity, time of year
describe the clinical signs of a kidney tumor
- unilateral leg lameness: renomegaly is a key rule out!!
describe the two types of nephrons that avians have
- cortical nephron: similar to reptilian nephron with no loop of Henle, short intermediate segment, oriented perpendicular to collecting duct
- medullary nephron: has a loop of Henle inserted between proximal and distal tubules, similar to mammalian nephronsm arranged parallel to collecting ducts (only 10-30% of nephrons are this type!)
do birds have a urinary bladder?
no; have a cloaca that functions for urinary, digestive, and repro
coprodeum: GI
urodeum: urinary
proctodeum: repro
vent is opening to cloaca
describe renal function in avians
- filtration and excretion processes: like mammals
- also: adaptations for water conservation
-need to absorb and use every molecule to help with flight - the amount of water absorbed in highly variable
-cloaca plays a huge role in ureteral peristalsis and force water back up as far high as to the ceca to reabsorb some more! - uricotelic: excrete uric acid!
-synth in liver and kidneys excrete from blood plasma partly by glomerular filtration and mainly by tubular secretion
-make semi solid urine = even more water conservation
compare and contrast renal blood flow between avians and mammalians
in avians: have a renal portal system!!
-renal portal valve in situated within the common iliac vein
-when this valve is open, blood is diverted away from the kidneys into the caudal vena cava
-when closed: blood is shunted through the kidneys
-this valve is inhibited by adrenaline and stimulated by acetylcholine
clinical consequences:
-because of the renal portal system and possible shunting of blood from intestines directly to kidneys, alimentary tract organisms may contribute to kidney disease!
-biggest disadvantage of using medial metatarsal vein is that some agents injected into the leg will go through the renal portal system and be excreted by KIDNEY TUBULES BEFORE entering circulation
-esp important if you inject antibiotics or other drugs in hind end (if excreted by tubular secretion; if by glomerular filtration you’re safe)
describe sexual dimorphism as relates to parrots
most parrots are not sexually dimorphic! (can’t tell sex just from looking at it)
most need DNA or endoscopig sexing
describe the repro tract of the cock
- 2 testis
- rudimentary phallus (may or may not use for repro, may just cloaca to cloaca)
-parrots cloaca to cloaca - psittacines, passerines, pigeons, and birds of prey all have no phallus
clinical consequences:
-phallus can prolapse and need to be amputated
-difference between phallus and penis: phallus only used for copulation (not needed for urination)
- medially, testis lie close to aorta and caudal vena cava
-each testicle suspended by a short mesorchium
-castration in adult birds in extremely risky! can bleed out; most owners ask you to do this when birds are vocalizing
-should only castrate immature birds (caponization) NOT in adults; and if you do it but leave ANY cells behind, can grow back
describe repro tract of the hen
- left ovary only!
- infundibulum, magnum, isthmus, uterus (shell and gland) and vagina
- egg formation and laying process:
-fertilization is not a prereq for egg formation and development!
-uterus holds egg during shell formation and majority of time is spent here; very vascular to aid with calcium deposition (shell gland)
-if egg gets stuck in hen can form a very hard shell - repro in bird follows a definite breeding cycle controlled by environmental factors: photoperiod, food, availability, temperature
-can modify in captivity!
-reduce caloric intake and shorten daylight is want to suppress egg laying
-if only use meds (common) is only a bandaid if physiology is not addressed - chronic egg laying resulting in uterine traffic jam is the number one reason for abdominal surgery in birds!
