Avian Repro Flashcards
Birds are seasonal breeders, mention three exogenous factors that are associated with breeding season
Ultimate factors for offspring survival (food)
12-14 hours of light = photosensitive phase
Rain in zebra finches and cockatiels
Proximate factors - vary year to year
-Initial predictive factors for gonadal development (photoperiod)
-Supplemental factors – social cues, territorial behavior, climate, nutrition
-Interaction with mates
-Modifying factors (loss of mate, disturbance of nest)
Above factors– > input in hypothalamus– > release of GnRH
What hormone causes stimulation of the pituitary to release FSH and LH?
GnRH
What is the function of FSH in birds?
ovarian and oviductal growth, gametogenesis, steroidogenesis
What is the function of LH in birds?
-steroidogenesis
Development of granulosa cells – > progesterone
– > surge of LH just prior to ovulation
– >stimulation of PGF2a from follicles
– >rupture of stigma and ovulation
Progesterone inhibits further ovulation, induces incubation
What is the difference between PGE2 and PGF2a?
PGE2 (and PGE1) effects – > vaginal relaxation
PGF2a– > uterine contractions– > release AVT (arginine vasotocin) from pituitary– > further contractions and release of PGs
What are the 5 regions of the oviduct?
IMIUV
*Infundibulum
Thin, facing left abdominal air sac
Tapers into tubular portion (chalaziferous region), thicker wall and mucosal folds
Motile to capture ovule
Fecundation site
Albumen starts to deposit, chalaze deposit at each end
15 minutes
*Magnum
Sudden enlargement of mucosal folds
Albumen, sodium, magnesium and calcium
3 hours
*Isthmus
Less prominent bands after short band without glands
Proteins added to albumen
Shell membranes
75 minutes
*Uterus
No distinct separation
2 areas: short, red region and a larger pouch-like region
Longitudinal folds transected by transverse furrows
Addition of water in the first 8 hours
Egg shell in the following 15 hours
20 hours
*Vagina
S-shape due to smooth muscle and connective tissue
Separated form uterus by sphincter
No glands, but spermatic fossulae (storage)
Describe the irrigation of the ovaries and oviduct
Ovarian arteries arise from left cranial renal artery or directly from the aorta
Oviduct is supply by: cranial renal artery or aorta (from aorta - supply to infundibulum and magnum), accessory cranial oviductal artery (from left external ileac artery - supply magnum), middle oviductal artery (left ischiatic artery - supply to magnum and uterus), caudal oviductal artery (from pudendal branch of internal ileac artery - supply to uterus) and vaginal artery(from pudendal branch- supply to vagina
Mention fetal and maternal causes for dystocia in birds
*fetal causes.
normal presentation of the egg is w. the blunted end of the egg exiting last.
abnormal presentation.
rotation along the long axis – > blunted end exiting first (“breach”).
rotation along the short axis – > neither end exiting first.
*maternal causes.
more medically challenging – > multifactorial nature of disease.
primary – > oviductal torsion, oviductal neoplasia, salpingitis.
secondary – > obstruction from surrounding organs (coelomic masses).
most common regions – > caudal uterus, vagina, vaginal-cloacal junction.
Mention three risk factors associated with dystocia/egg binding?
nutrition – > Ca, VitE, selenium deficiency of greatest concern.
inadequate nutrition – > inadequate smooth muscle contraction + improper egg formation (soft/malformed eggs).
chronic egg laying – > may predispose to abnormalities/damage of oviduct musculature.
systemic disease, obesity, lack of exercise, nulliparous status, previous dystocia, persistent R oviduct.
any species can be affected.
overrepresented – > smaller birds – > canaries, lovebirds, finches, budgies, cockatiels.
Mention 2 radiographic findings that could be seen in a bird with dystocia/egg binding
Mineralized eggs, soft-shelled or collapsed eggs may not be well defined.
medullary hyperostosis of long bones – > new medullary bone formation secondary to circulating estrogen.
Mention the main biochemistry changes in a bird with reproductive upregulation
increased ALP, globulins, cholesterol, CK, triglycerides (more triglycerides in the yolk than the cholesterol), hypercalcemia
Mention the medical management for dystocia in birds
Eggs are laid every 24-36 hours. May need more time
thermal support (85-90F), calcium, SQ/IV fluids, analgesics.
easy access to food/water and general nutritional support.
antibiotics if suspicion of infectious etiology or infectious sequela (eg ruptured oviduct).
supportive care may be only treatment required.
HOWEVER – > close monitoring is essential – > any decline in overall condition warrants further intervention.
if non-responsive to supportive care and no concern for oviductal obstruction/adhesion/perforation …
prostaglandin and hormone therapy could be applied.
may be challenging to acquire these products, safety concerns for patient/clinician.
if non-responsive to hormonal therapy – > more aggressive measures to be considered.
general anesthesia for maximum relaxation.
gentle massage of lower coelom and uterovaginal sphincter/vaginal opening – > vaginal relaxation – > oviposition.
digital manipulation of egg within caudal oviduct – > stimulate caudal movement of egg – > could predispose to oviductal tear ± egg collapse.
What is the function of oxytocin in birds?
Contraction of uterine smooth muscle - DOES NOT relax the uterovaginal sphincter - use only if relaxed
What is the function of PGF2a in birds
Generalized smooth muscle contraction - DOES NOT relax the uterovaginal sphincter - use only if relaxed
Systemic side effects
What is the function of PGE2
Relaxes uterovaginal sphincter and vagina, increases uterine contractions
