vet-tech-therio-ch-10

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darlene.m.nelson
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vet-tech-therio-ch-10
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2011-11-16 19:26:07
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vet tech theriogenology chapter 10 reproductive anatomy physiology dog set
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vet tech theriogenology chapter 10 reproductive anatomy and physiology of the dog set
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  1. Ovaries
    • female gonads
    • - hormones
    • - reproductive cells
    • paired oval glands
    • abdominal cavity
    • caudal to the kidneys
    • produce eggs
    • blood supply
    • - ovarian artery
    • - uterine artery
    • release 2 hormones:
    • - 1. estrogen - controls female characteristics
    • - 2. progesterone - maintain pregnancy
  2. Uterine tube
    • aka oviduct (birds, lower mammals) or Fallopian tubes
    • transport oocytes to uterus:
    • - 1. prepared for fertilization
    • -- a. infundibulum
    • -- b. muscle contractions, movement of cilia move oocytes down towards the uterus
    • -- c. oocyte requires 2 days of maturation in the uterine tube before it is capable of being fertilized
    • - 2. are fertilized
    • - 3. 1st stages of embryonic development
  3. Infundibulum
    • ovarian extremity of uterine tube
    • opening where ova enter uterine tube from ovary
  4. Uterus
    • aka "womb"
    • houses developing embryos => fetuses
    • y shaped
    • 2 uterine horns
    • - cranial end connected to caudal end of corresponding uterine tube near the ovary
    • - length of horns much greater than diameter
    • short body - connected to each horn
    • neck (cervix) - channel, thick firm tissue between uterus and vagina (very tip or base)
    • varies in size:
    • - size and weight increase during estrous cycle (aka heat cycle)
  5. Wall of uterus
    • 3 layers
    • - 1. serosa
    • - 2. myometrium
    • - 3. endometrium
  6. Serosa
    outer, thin covering of peritoneum
  7. Myometrium
    • muscular portion
    • metritis is inflammation of myometrium
    • 2 layers:
    • - 1. outer longitudinal
    • - 2. inner, thicker, circular layer
    • important during parturition
  8. Endometrium
    • inner, thickest layer
    • glands, blood vessels
  9. Pyometria
    infected uterus
  10. Vagina
    • aka "birth canal"
    • musculomembranous canal
    • opens caudally into vulvar area just ahead of the urethral opening
    • vaginal mucosa undergoes dramatic changes during estrous cycle
    • - vaginal cytology
    • longitudinal and transverse folds
    • - allows for expansion during mating, pregnancy and whelping
  11. Vulva
    • aka labia (lips)
    • form the external boundary of the vulva
    • soft and pliable
    • join ventrally to form a pointed projection that extends downward and backward from the body
    • may change in size during the estrous cycle or pregnancy
    • the only external part of the female reproductive system
  12. Spaying
    • don't want to spay a dog in heat - want to wait 8-12 weeks
    • will do cat in heat
  13. Mammary glands
    • modified sweat glands
    • two bilaterally symmetrical rows
    • extend from ventral thoracic (chest) to inguinal (groin) region
    • number of glands varies from 8-12 (4-6 on each side of midline)
    • typically 10:
    • - thoracic mammae - cranial 4
    • - abdominal mammae - following 4
    • - inguinal mammae - caudal 2
  14. Puberty
    • period when the capability of reproduction is attained (first estrous)
    • 5-18 months old
    • depending on breed and sire (genetics)
    • nutrition - poor nutrition can delay/stop estrous
    • smaller breeds - earlier estrus than larger breeds
    • most breeds:
    • - 2 cycles per year
    • - Basenji - 1 cycle per year
    • - Collie - every 9 months
    • - German Shepards - every 26 weeks
  15. The Canine Estrous Cycle
    • aka "season"
    • 4 stages:
    • - proestrus
    • - estrus
    • - diestrus (aka metestrus)
    • - anestrus (an = without)
    • gestation for dog is ~63 days
  16. Proestrus
    • follicular growth
    • bitch is attractive to male, but she will not allow mating
    • predominant hormone is estrogen
    • raised levels of estrogen cause:
    • - production of pheromone that make female attractive to male
    • - serosanguinous vaginal discharge ("blood spotting")
    • - vulva becomes enlarged and protrudes
    • - wall of vagina becomes swollen
    • - increase in number of layers of cells of the epithelial lining of the vagina
    • -- outer layers die and slough off
    • - pituitary stops secreting FSH
  17. Estrus
    • - bitch will accept dog's advances, allow mating
    • - estrogen levels fall, progesterone levels rise which results in...
    • - reduction in vaginal mucous swelling and edema
    • - behavioral estrus
    • -- "slipping the tail" - moving the tail to one side to allow intromission
    • - ovulation of a follicle results in a corpus luteum (secretes progesterone)
    • - different breeds of dogs will ovulate different numbers of follicles:
    • -- bigger breeds have bigger litters
    • - once ovulation and fertilization occurs, the bitch will stop accepting the male
  18. Metestrus (diestrus)
    • two month stage following estrus when the reproductive organs are under the influence of progesterone from the corpus luteum
    • action of progesterone:
    • - causes proliferation of uterine glands (to support muscular contractions for parturition) and support pregnancy
  19. Anestrus
    • period of rest
    • reproductive organs are inactive
    • preferred period to spay dog
  20. Determination of time to breed
    • establish when ovulation takes place in order to coordinate mating with this event
    • ways to determine:
    • - 1. measurement of LH peak in peripheral blood
    • - 2. character of vaginal mucosa
    • - 3. vaginal epithelial cytology
    • - 4. measurement of peripheral blood progesterone
    • relied on vaginal cytology for years & estrogen levels (not particularly accurate)
  21. Measurement of LH peak in peripheral blood
    • ovulation closely correlated with LH surge
    • LH surge transitory - would need multiple blood samples every 10-15 minutes to not miss peak
    • LH surge may happen on one day
    • not practical
  22. Character of vaginal mucosa
    • Proestrus - vaginal mucosa is edematous, round, pink, glistening
    • decreased estrogen levels, increased progesterone levels - mucosa becomes shrunken and wrinkled
    • view hormonal changes - vaginoscope or endoscope
  23. Vaginal epithelial cytology
    • cells can be anuclear, superficial, intermediate, parabasal
    • see pic in slides
  24. Measurement of peripheral blood progesterone
    • most accurate method of predicting ovulation
    • most used now
    • progesterone levels begin to rise before ovulation takes place
    • - unique to the dog
    • - doesn't happen in the cat
    • can do:
    • - ELISA (Ovucheck PreMate (TM)) in house testing
    • - outside laboratory testing
    • - rarely performed in most practices, so usually outside lab
  25. How to breed
    • 1. natural breeding
    • - goal - achieve best conception rate and litter size with least labor and cost
    • - one or more breedings (alternate days) during behavioral estrus ususally results in pregnancy
    • 2. artifical insemination
  26. Prior to breeding
    • General physical exam
    • - general health
    • - reproductive system
    • -- abnormal vulvar confirmation
    • -- vulvar discharge
    • -- digital (finger) exaination (>7 kg) for tumors, foreign bodies, abnormalities
    • -- mammary glands - palpate for tumors, other abnormalities
    • - current immunizations
    • - testing for heartworm and other parasites - i.e. Brucella canis (brucellosis)
    • - genetic testing for certain breeds, for example:
    • -- hip/elbow dysplasia - shepards, etc
    • -- heart disease - boxers, King Charles spaniels
    • -- thyroid disease
    • -- ocular conditions - collies
  27. Fertilization
    • takes place in the uterine tube (between ovary and uterine horn)
    • early embryo is in the uterine horn (by 9-10 days)
    • implantation doesn't occur immediately (occurs at about 19-20 days)
  28. Pregnancy
    • progesterone - dominant hormone of pregnancy
    • pseudocyesis (false pregnancy) - little or no difference in levels of progesterone in pregnant & non-pregnant bitch
    • relaxin
    • gestation length - ~63 days (56-72)
  29. Relaxin
    • pregnancy specific hormone produced by placenta and ovary
    • rises gradually in the last 2/3 of pregnancy
    • detectable from day 25 of gestation
  30. Parturition
    act of giving birth
  31. Eutocia
    normal parturition
  32. Dystocia
    difficult parturition
  33. Pregnancy diagnosis
    • abdominal palpation
    • - don't want to rely solely on this
    • transabdominal ultrasonography
    • transabdominal radiography
    • - better (easier to) count than with ultrasonography
    • - as long as its only 1 radiograph, it doesn't seem to be harmful
    • peripheral blood relaxin levels
    • doppler ultrasound
    • transabdominal auscultation
  34. Abdominal palpation
    • 3-4 weeks
    • - individual fetal swellings can be palpated through the abdominal wall
    • - "bumps" 12-15 m (~1/2 inch) diameter along the uterine horn
    • 5-6 weeks
    • - difficult to palpate pregnancy
    • 6-7 weeks
    • - can palpate fetuses due to ossification
    • - can identify fetal heads
    • - difficult to identify number of puppies
  35. Transabdominal ultrasonography
    • 3 weeks and later
    • - can detect fetal fluids and fetuses
    • - can determine fetal heartbeat and viability of fetus
    • most reliable method
  36. Transabdominal radiography
    • 6-7 weeks
    • - can determine fetal skeletons
    • - can detect fetal death due to skeletal degeneration and putrefying gases
  37. Peripheral blood relaxin levels
    • relaxin
    • - pregnancy-specific hormone
    • - begins to rise 21-26 days after conception
  38. Doppler ultrasound
    sound waves throught the abdominal wall are reflected at a different frequency when they hit moving fluid (blood in fetal umbilical veins or heart)
  39. Transabdominal auscultation
    • stethoscope used late in pregnancy to hear fetal heart beats
    • fetal heart rate is twice that of dam in both dog & cat
  40. Parturition
    • aka whelping
    • high levels of progesterone (maintains pregnancy) dampen the normal contractions of the uterus
    • onset of parturition is initiated by luteolysis (corpus luteum) and reduction in the level of progesterone
    • triggered by signals from the fetus
    • raised levels of corticosteroids (ACTH) one day prepartum
    • no raised levels of estrogen
    • three stages of labor
  41. First stage labor
    • increased uterine muscle contractions
    • lasts 6-36 hours
    • preceded by drop in body temperature (BT) by 2 degrees (to 99 degrees)
    • bitch appears restless and nervous, looking at flanks (esp first timers)
    • looking for a quiet place to make a nest
    • vagina relaxes and cervix dilates
    • fetus rotates - head is pointing towards the cervix
    • posterior presentation can be normal
    • transverse presentation (across birth canal) is dystocia
  42. Second stage labor
    • involuntary uterine & voluntary abdominal wall contraction and expulsion of the fetus
    • completed within 3-12 hours
    • lateral recumbency
    • visible abdominal straining
    • first puppy should appear within 2-hours
    • STRONG abdominal straining puppy may appear within 20-30 minutes
    • interval between each puppy should NOT be more than 2-4 hours
    • expulsion of green fluid, "lochia" - allantochorionic fluid, "the breaking of the waterbag"
    • bitch licks puppy to clean/dry, stimulate breathing
  43. Third stage of labor
    • expulsion of the placenta (fetal membranes)
    • occurs within 10-15 minutes of the pup or may follow the birth of each pup
    • leave the parturient bitch in peace (unless she needs you)
    • +/- attend to neonate
  44. Nursing assistance at parturition
    • with C-section, puppies will almost always have some anesthetic effects
    • amniotic memebrane may need to be broken (to allow puppy to breathe)
    • vigorous rubbing dry and warm the puppy, stimulate breathing
    • gently suck fetal fluids with a plastic pipette (or baby nasal bulb) that may be blocking airways (carefully swing puppy downwards)
    • clamp umbilical cord with sterile forceps or cut to 4 cm with sterile scissors
    • - +/- ligate cord with sterile absorbable suture
    • +/- guide pups to nurse
  45. Completion of parturition
    • completed within 6 hours of second stage labor
    • >12 hours considered abnormal
    • prolactin levels rise (triggers lactation)
    • suckling by the puppies stimulates oxytocin release - initiates milk letdown
  46. Lactation
    • during pregnancy:
    • - mammary glands develop in response to gradual increase in levles of prolactin
    • parturition:
    • - progesterone levels drop
    • - prolactin levels rise
    • lacation last for about 6-9, prolactin levels remain elevated
    • maintenance of lactation also requires cortisol and insulin
  47. Dystocia maternal factors:
    • primary uterine intertia
    • - failure to expel normal-sized fetuses through a normal birth canal
    • - incompletely dilated cervix
    • secondary uterine inertia
    • - prolonged uterine contractions fail to expel a fetus
    • - obstructing birth canal
    • breed
    • - brachycephalic breeds: broad head, narrow pelvis, C-section
    • confirmation
    • - congenital/acquired abnormalities:
    • -- old healed fractured pelvis
    • -- vaginal prolapse - common in boxers
    • -- vaginal neoplasia
  48. Dystocia fetal factors
    • presentation, position, posture
    • abnormal fetal development
    • - fetal monsters
    • - hydrocephalic puppies
    • - multiple limbs
    • - abdominal and/or thoracic hernia
    • partially delivered puppy - stuck in birth canal
  49. Dystocia treatment
    • 1. removal of puppy manually
    • 2. medical treatment - oxytocin - to increase uterine contractions
    • 3. Cesarean section
    • 4. Eclampsia - low calcium levels - can cause convulsions/coma in mom
  50. Pseudocyesis
    • aka false pregnancy
    • some non-pregnant bitches may lactate weeks after their heat cycle (season)
    • lactation in the abscence of pregnancy
    • does not show signs of pregnancy (Sheila disagrees - has seen nesting behaviors)
    • may be caused by a steep drop in progesterone or greater sensitivity by some animals to the normal decline...
    • - ...causes the release of prolactin and the induction of lactation
  51. Manipulation of reproduction in the bitch
    • spaying
    • interruption of behavioral estrus
    • induction of estrus
    • treatment of pseudosyesis
    • termination of pregnancy
    • induction of milk letdown
    • induction of parturition
    • most of these mess with hormones
  52. Spaying
    • ovariohysterectomy (OHE) - surgical removal of the ovaries and the uterus
    • in Europe often doing ovariectomy
    • - smaller incision, faster surgery
    • - no medical reason to do it this way
    • - can still get pyometria this way
  53. Interruption of behavioral estrus
    administration of oral or injectable progesterone to block the production of follicle stimulating hormone (FSH)
  54. Induction of estrus
    administration of anti-prolactin to supress luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion
  55. Treatment of pseudocyesis
    can treat lactation in the absence of pregnancy with progesterone (aka anti-prolactin) - preferred treatment
  56. Termination of pregnancy
    • administration of a specific anti-progesterone
    • removal of the corpa lutea which produce progesterone
    • - use of anti-prolactin
    • - prolactin necessary to support the corpus luteum
    • combination of anti-progesterone and anti-prolactin
  57. Induction of milk letdown
    • mammary gland development, but no milk being secreted
    • administer oxytocin
  58. Induction of parturition
    • administer corticosteroids
    • this stimulates the production of enzymes
    • convert progesterone to estrogen
    • increases uterine contractions
    • triggers parturition
    • to start this, need:
    • - viable placentae
    • - uterine myometrium capable of contraction
    • - to be close to term

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