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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
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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
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Infundibulum
- ovarian extremity of uterine tube
- opening where ova enter uterine tube from ovary
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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)
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Wall of uterus
- 3 layers
- - 1. serosa
- - 2. myometrium
- - 3. endometrium
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Serosa
outer, thin covering of peritoneum
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Myometrium
- muscular portion
- metritis is inflammation of myometrium
- 2 layers:
- - 1. outer longitudinal
- - 2. inner, thicker, circular layer
- important during parturition
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Endometrium
- inner, thickest layer
- glands, blood vessels
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Pyometria
infected uterus
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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
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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
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Spaying
- don't want to spay a dog in heat - want to wait 8-12 weeks
- will do cat in heat
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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
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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
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The Canine Estrous Cycle
- aka "season"
- 4 stages:
- - proestrus
- - estrus
- - diestrus (aka metestrus)
- - anestrus (an = without)
- gestation for dog is ~63 days
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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
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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
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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
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Anestrus
- period of rest
- reproductive organs are inactive
- preferred period to spay dog
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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)
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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
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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
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Vaginal epithelial cytology
- cells can be anuclear, superficial, intermediate, parabasal
- see pic in slides
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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
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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
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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
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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)
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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)
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Relaxin
- pregnancy specific hormone produced by placenta and ovary
- rises gradually in the last 2/3 of pregnancy
- detectable from day 25 of gestation
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Parturition
act of giving birth
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Eutocia
normal parturition
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Dystocia
difficult parturition
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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
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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
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Transabdominal ultrasonography
- 3 weeks and later
- - can detect fetal fluids and fetuses
- - can determine fetal heartbeat and viability of fetus
- most reliable method
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Transabdominal radiography
- 6-7 weeks
- - can determine fetal skeletons
- - can detect fetal death due to skeletal degeneration and putrefying gases
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Peripheral blood relaxin levels
- relaxin
- - pregnancy-specific hormone
- - begins to rise 21-26 days after conception
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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)
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Transabdominal auscultation
- stethoscope used late in pregnancy to hear fetal heart beats
- fetal heart rate is twice that of dam in both dog & cat
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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Interruption of behavioral estrus
administration of oral or injectable progesterone to block the production of follicle stimulating hormone (FSH)
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Induction of estrus
administration of anti-prolactin to supress luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion
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Treatment of pseudocyesis
can treat lactation in the absence of pregnancy with progesterone (aka anti-prolactin) - preferred treatment
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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
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Induction of milk letdown
- mammary gland development, but no milk being secreted
- administer oxytocin
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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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