Small Animal Reproduction PDF

SMALL ANIMAL REPRODUCTION Chapter 10 Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 1 ANIMAL REPRODUCTION: WHY? Perpetuation of species Financial considerations Human needs Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 2 FEM...

SMALL ANIMAL REPRODUCTION Chapter 10 Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 1 ANIMAL REPRODUCTION: WHY? Perpetuation of species Financial considerations Human needs Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 2 FEMALE REPRODUCTIVE ANATOMY Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3 MALE REPRODUCTIVE ANATOMY Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 4 FEMALE REPRODUCTION  Estrous=type of cycle; time from the beginning of one heat period to the beginning of the next  Dogs-diestrous (2 cycles per year)  Cats-seasonally polyestrous (spring to fall)  Estrus=part of the estrous cycle when female is in “heat” & sexually receptive (time when breeding can take place)  Dogs 9 (3-21) days  Cats 10 days  Puberty=first ovulation occurs +/- signs of heat  Sexual receptiveness=brought about by ratio of estrogen to progesterone Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 5 REPRODUCTIVE CYCLE BEGINNINGS Higher Brain Centers Hypothalamus (GnRH Released) Pituitary Anterior Pituitary (Gonadotropins, FSH & LH, released) Ovary (estrogen & progesterone Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. released ) 6 REPRODUCTIVE HORMONES Gonadotropin-releasing hormone (GnRH)  From hypothalamus  Stimulates secretion of FSH Follicle-stimulating hormone (FSH)  From anterior pituitary  Stimulates development of ovarian follicle and estrogen secretion (in female)  Results in growth and release of sperm cells (in male) Estrogen—hormone of estrus Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 7 REPRODUCTIVE HORMONES  Luteinizing hormone (LH)  From anterior pituitary  Results in ovulation in the female  Triggers ovarian follicle conversion into progesterone secreting corpus luteum (CL)  Results in testosterone production in the male  Progesterone—hormone of pregnancy or diestrus  Inhibin along with progesterone  Feeds back to hypothalamus to decrease GnRH  Prostaglandin F2alpha—released from the uterus—causes CL regression along with drop in progesterone, if fertilization has not occurred Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 8 OVULATION  Females are born with a finite amount of oocytes  Ovulation is defined as ejection of an egg from a follicle on the ovary  Process begins in the brain when Anterior Pituitary releases FSH  Results in follicular growth/development  A sudden spike or release of LH causes the follicle to ovulate  After ovulation, the follicle fills with blood – this is called the corpus hemorrhagicum (CH)  The CH develops into a corpus luteum (CL) which produces progesterone Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 9 FERTILIZATION/IMPLANTATION  Penetration of ovum by single sperm  Occurs in last part of oviduct (fallopian tube)  Fertilized ovum (zygote) passes into uterus  Implantation occurs  Zygote releases early conception factor (ECF) protects zygote from being targeted as foreign body/destroyed by maternal immune system  Zygote develops into embryo  Outermost layer becomes placenta  Uterine-placental attachment varies in number of layers  Number of placental layers affects IgG antibody transfer from mother to fetus  Determines if newborn has antibody protection at birth or dependent on colostrum consumption Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 10 FERTILIZATION/IMPLANTATION Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 11 MATURATION OF SPERM  Spermatogenesis completed w/in testicles  Sperm are NOT mature until they pass through the epididymis  Within epididymis acquire motility/ability to fertilize ova  Sperm stored in the tail of the epididymis  Sperm cells in the tail of epididymis moved from ductus deferens into the ampulla  Sperm mixed with secretions from accessory sex glands (prostate, vesicular glands, and/or bulbourethral glands) to form semen  Once sperm enters female tract, sperm cells must undergo capacitation in order to be able to fertilize an egg  Uterine contractions move sperm rapidly to oviduct for fertilization Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 12 QUICK REVIEW OF HORMONES GnRH (from hypothalmus) → stimulates secretion FSH (from pituitary) →stimulates growth ovarian follicles & estrogen secretion from the ovary → increasing estrogen causes endometrium (uterine lining) become highly vascularized and engorged w/blood → leads to serosanguinous discharge from vulva (increased estrogen levels also cause hyperemia & swelling of vulva) Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 13 FEMALE REPRODUCTIVE EVENTS IN DOGS  Puberty = time of first ovulation  Occurs between 6-24 months of age  Proestrus = time leading to estrus  ~9 days  Estrus = time of sexual receptivity and mating (ovulation occurs)  ~9 days  Diestrus = time of pregnancy establishment  ~60 days  Anestrus = time when female is not undergoing reproductive events  ~4months  All together, proestrus through anestrus (four stages of estrous cycle) lasts about 6-7 months in the female dog Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 14 PROESTRUS  Beginning is designated by serosanguinous vaginal discharge (bloody)  FSH & Estrogen are increasing  External genitalia becomes swollen  She attracts the male but will not stand for breeding Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 15 PROESTRUS - CYTOLOGY  Gradual shift from intermediate and parabasal cells to superficial cells  Typically large numbers red blood cells  Neutrophils commonly observed  Large numbers of bacteria often present Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 16 ESTRUS  Rapid increase LH (“LH surge”) occurs at start of estrus  Ovulation occurs approximately 2 days after surge  Followed by conversion of follicle into progesterone producing CL  Ova aren’t mature at time of ovulation  Requires additional 2 days to fully mature in oviduct  Remain fertilizable for 3 days  Time period that female will be receptive to the male  Seeks male & will stand for breeding  Vaginal discharge becomes clear to brown  Vulva appears smaller due to a decline in estrogen Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 17 ESTRUS - CYTOLOGY  Predominance superficial cells  Most will undergo full cornification  Smear will reveal a monotonous pattern  Predominately cornified epithelial cells (anucleate superficial cells)  Bacteria attached to superficial cells Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 18 DIESTRUS Diestrus (metestrus):  Stops standing for male  Controlled by progesterone  Ends when pregnant bitch whelps or non pregnant bitch’s progesterone level drops to less than 1ng/mL  Parturition occurs w/in 24 hours after CL no longer functional & progesterone drops below 1 ng/mL  The same length of time whether bitch is pregnant or not  Lasts approximately 60-90 days  Little discharge or vulvar swelling during this stage  Cervix constricts Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 19 DIESTRUS - CYTOLOGY  Decline in the number of superficial cells  Reappearance of intermediate & parabasal cells  Fewer red blood cells than in proestrus  Neutrophils may contain phagocytized RBCs & bacteria  Can resemble proestrus Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 20 ANESTRUS Anestrus:  Reproductive inactivity  Uterus is returning to normal after estrus or parturition  Lasts approx. 120 days  No ovarian activity until close to next estrous cycle Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 21 ANESTRUS - CYTOLOGY Intermediate and parabasal cells predominate No superficial cells Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 22 VAGINAL SAMPLE EXAMINATION Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 23 VAGINAL SAMPLE EXAMINATION Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 24 REPRODUCTIVE EVALUATION TECHNIQUES  Vaginal cultures for bacteria  Prebreeding evaluation for fertility  Abnormal discharge  Vaginal cytology  Used to follow the estrous cycle  Microscopic evaluation of cells from vagina  Hormone assays  Serum progesterone & LH used to pinpoint time of ovulation & calculate optimal breeding times in dogs exhibiting signs of estrus  More precise than monitoring clinical signs & vaginal cytology Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 25 PROGESTERONE ASSAY TECHNIQUES  Commercially-available in- house kits to assay either LH or progesterone  Results available in 20 minutes  LH can be tested, but requires daily serum collection  Used to help determine the time of ovulation Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 26 BREEDING  Occurs during estrus  Bitch will flag w/tail raised & held to one side  She will stand for the male to breed  Natural breeding they will be “locked” together (tied) for half an hour or more  Tie due to engorgement of bulbus gland at base of penis  Can also AI  Fertilize w/in 12 hours of thawing semen (if frozen)  Fresh semen stays fertile for 3-5 days  Timing of breeding  Natural breeding best done when progesterone reaches serum concentration 2ng/mL or on day 2-4 of LH surge Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 27 GESTATION Lasts approximately 60-63 days from fertilization Placenta type is endotheliochorial w/ zonary attachment area Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 28 PREGNANCY DETERMINATION IN THE CANINE  Several methods available  Abdominal palpation (21-30 days)  Hormone assay – relaxin (3-4 weeks to term)  Ultrasound (21-28 days after insemination to term)  Radiography  After day 43-45 can see ossification of fetal skeletons  Best modality to determine number of fetuses, size in Radiograph relation to pelvis (2-4 days before due date) Ultrasound Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 29 PARTURITION: 3-STAGE PROCESS Parturition = whelping = birthing Stage I: Preparation for delivery Stage II: Fetal expulsion Stage III: Expulsion of placenta Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 30 CANINE PARTURITION: STAGE I  Preparation for delivery  Pelvic ligaments relax, cervix softens  Uterine contractions without abdominal contractions  Lasts 6-12 hours (up to 36 hours)  Behavior  Restlessness  Nesting  Nervous/trembling  Panting  Body temperature drops to 99° F 24 hours prior to stage II (about 85% of dogs) Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 31 CANINE PARTURITION: STAGE II  Delivery of puppies (whelped)  Lasts 3-6 hours (up to 24 hours)  Presentation of puppies  60% are anterior in the bitch  20-60 minutes per puppy  No more than 2 hours between delivery of puppies Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 32 CANINE PARTURITION: STAGE III Expulsion of the placenta Normal blackish-green discharge  Comes from sites of placental attachment Professional assistance or cesarean section required if pup gets stuck Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 33 CANINE PARTURITION: DYSTOCIA  Dystocia is difficult birth  Guidelines for seeking veterinary intervention:  No progress after 30 minutes of STRONG, CONTINUAL contractions  No progress after 2 hours of WEAK, INFREQUENT contractions  Prolonged interval between pups (more than 2 hours)  “Stuck” puppy-due to malpositioning or large size  Evaluation techniques  Ultrasound-assess fetal viability  Radiography-number of pups, relative size, position Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 34 POSTPARTUM PROBLEMS  Normal long uterine involution period in canines  Normal vulvar discharge  Non-odorous and hemorrhagic  Can last for 8-10 weeks after whelping  If 12 weeks or more, suspect subinvolution of the placental sites (SIPS)  Unhappy, hungry, fussy, neglected puppies  Foul-smelling vaginal discharge  Green discharge from retained placenta Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 35 MORE POSTPARTUM PROBLEMS  Metritis  Inflammation of uterus/endometrium  Results in foul-smelling vaginal discharge  Puppies may need supplemental hand- feeding  Mastitis  Inflammation of mammary glands  Fever, lethargy, glands are swollen/discolored  Puppies may need supplemental hand- feeding Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 36 EMERGENCY POSTPARTUM PROBLEM ECLAMPSIA (hypocalcemia)  Can be life threatening  More common in smaller breeds  Symptoms  Tremors, excitation, hyperthermia, convulsions  Treatment  Administer supplemental calcium  Sedation or short-term anesthesia Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 37 EMERGENCY POSTPARTUM PROBLEM PYOMETRA  Uterine infection  Can be life threatening  Progesterone related  Symptoms  Lethargy, depression, febrile, polyuria, polydipsia, vomiting  Leukocytosis, enlarged fluid-filled uterus  Treatment  Emergency Ovariohysterectomy Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 38 UNIQUE ASPECTS OF THE FELINE FEMALE REPRODUCTIVE CYCLE  Female cats = queens  Seasonal breeders  Long-photoperoid breeders (long days)  Most queens have estrous cycles during spring  Artificial lighting may affect cycles of indoor cats  Induced ovulators  Felines do not ovulate during every estrous cycle  Queen must have vaginal stimulation to induce LH surge (causing ovulation) Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 39 ESTROUS CYCLE – QUEEN Estrus  Signs:  Increased vocalization  Rolling  Lordosis posture  Anorexia cdn.citl.illinois.edu  +/- Urine spraying  No vulvar discharge Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 40 ESTROUS CYCLE – QUEEN  Estrogen concentration increase during estrus & decrease after ovulation/regression of unovulated follicles  Breeding recommended after day 3 of estrus  LH released within minutes of copulation  Less 50% cats ovulate w/single mating  Multiple breedings recommended if pregnancy/kittens are goal  Outcomes of estrus when breeding occurs  Pregnancy (CL forms)  Bred but no pregnancy (CL forms)  No ovulation (no CL)  If no ovulation occurs, no CL forms, no progesterone produced & queen will return to estrus in 3-14 days Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 41 GESTATION – QUEEN  Fertilization occurs in the oviducts  Fertilized eggs migrate to uterine horns & implant  Placentation is zonary endotheliochorial (same as canine)  Gestation 63 days  Observable signs of pregnancy  Increased size of teats by weeks 2-3  Increased mammary enlargement through term  Weight gain obvious by mid-gestation Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 42 PREGNANCY DIAGNOSIS IN QUEEN Abdominal palpation  18-30 days after fertilization Ultrasound  16 days (detectable heartbeats) after fertilization to term Radiography  After 40 days to term  If wanting counts done radiograph about 60 days Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 43 PARTURITION – QUEEN  Build nests  Lasts from couple hours to over a day  Stage 1  Begins with uterine contractions w/o abdominal contractions  Decreased general activity  Behavior changes (more social/less social)  Fetal movements increased  Lactational secretion evident  Ends when chorioallantoic membrane ruptures Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 44 PARTURITION – QUEEN Stage 2  All fetuses delivered Stage 3  Placentas passed  Uterus returns to normal size rapidly  Endometrium recovery takes several weeks Queens can return to estrus & get pregnant while nursing kittens depending on time of year Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 45 DYSTOCIA – QUEEN  Not common  If occurs usually purebred  Fetal causes:  Large size, lateral deviation of head, breech presentation  Maternal causes:  Uterine torsion, primary/secondary inertia, small pelvic size  Cesarean section if does not progress w/in reasonably short time or if queen or fetus is distressed Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 46 REFERENCE McCURNIN’S TEXTBOOK  Chapter 10  Hormones & reproductive cycles can be confusing and difficult to follow  Book provides great box summaries and tables for reference  Also includes large animal reproduction not discussed in this class  Use your textbook for reference while studying PowerPoint slides Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 47 QUESTIONS? Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 48