Canine Reproductive Pathophysiology

Canine Reproductive Pathophysiology

• Introduction covers general information for the course
• Email Meera Gatlin with questions or to schedule a meeting in the Wildlife Building, room 115
• There is no syllabus for this course
• The exam will cover the PowerPoints and lectures
• The term "dog/bitch" denotes an intact male or female

Study Objectives

• Review the reproductive systems of the bitch and dog and their relevance to estrus, breeding and copulation
• Understand the hormonal changes through the canine estrus cycle and link them to behavioral and clinical changes
• Visually identify cytological changes through each stage of the canine estrus cycle
• Discuss the importance of canine ovulation timing for optimal breeding management
• Convey the importance of hormonal physiology in health concerns like pyometra, ovarian remnant syndrome, benign prostatic hypertrophy, and in spay/neuter guidelines
• List the necessary parameters to evaluate canine semen
• Describe the type of placentation found in canines
• Understand the physiology of pregnancy and parturition

Reproductive Anatomy of the Bitch

• The ovaries are caudal to the corresponding kidneys and 1-3cm long
• The ovaries are located within the ovarian bursa
• Pictured are the stages of ovarian activity
• Uterine tubes (AKA Fallopian Tubes, or Oviducts) transport oocytes from the ovary to the uterus
• The ovarian end of the uterine tube is the infundibulum with fimbriae
• The middle of the uterine tube is the ampulla, where fertilization occurs
• The uterine end of the uterine tube is the isthmus with crypts for sperm docking
• Prevents backflow from the uterus
• Bicornuate: Suspended by the broad ligament
• Long uterine horns contain the developing embryos
• Short uterine body is where the two uterine horns meet
• The cervix is a short, thick-walled muscular sphincter that connects the uterus with the vagina
• The cervix is located within the abdomen and averages 1.5-2 cm
• The vagina's epithelial lining undergoes hormonal changes during estrus; is oriented along the longitudinal axis of the body
• During proestrus, the vaginal mucosa is edematous and pink
• During estrus, the vaginal mucosa becomes a pale pink
• During estrus, reduction in edema causes a crenulated appearance
• During diestrus, mucosa appears patchy and hyperemic, and tissue is irritable
• Vestibule: Between the lips of the vulva and the vagina
• Mammary: Typically have 10 (range 8-12) mammary glands, arranged in bilaterally symmetric rows
• Two thoracic, two abdominal and one inguinal on each chain

Canine Puberty

• Typically occurs between 6 and 24 months
• Is Influenced by breed, size, environment and body condition
• Look at familial repro history for predictions
• First heats can be less predictable and split

Canine Hormones

• FSH promotes ovarian follicular development
• Estrogen prepares the repro tract for coitus
• Estrogen has a negative effect on FSH and stimulates LH
• LH (luteinizing hormone) signals the start of estrus and the transition to the luteal phase
• LH release causes follicles to rupture and form the corpus luteum (CL), which releases progesterone (P4)
• P4 causes behaviors and prepares the repro tract for fertile ova

The Canine Estrous Cycle

• The canine estrous cycle is monoestrous, twice yearly but can range from 1-4 per year, and possibly non-seasonal
• The cycle phases: anestrus, proestrus, estrus/ovulation, and metestrus/diestrus
• The cycle phases: Anestrus, Proestrus, Estrus, and Diestrus ( metestrus term is not preferred) or Interoestrus (prolonged diestrus). Note how the estrous stages correlate with hormone levels
• Estradiol peaks in proestrus (follicular phase), which lasts roughly 9 days
• The bitch is attractive to males but unwilling to stand to be mated
• Presents with vulvar swelling and serosanguinous discharge
• Progesterone begins to rise in late proestrus
• Contains a mix of epithelial cells, extracellular bacteria, red blood cells and white blood cells (early to mid-proestrus)
• Normal range for proestrus: 0-27 days
• As estradiol drops to basal concentrations and progesterone increases rapidly, the estrus phase begins (roughly 9 days)
• The LH surge occurs at this time
• The bitch is receptive to mating
• Vulva softens but is still swollen, and vaginal discharge gradually lightens in color
• Follicles ovulate primary oocytes, which undergo a final meiotic division to secondary oocytes
• CL develops, with >90% cornified epithelial cells, +/ extracellular bacteria, and reducing RBCs until there are rare to no WBCs
• Range from 4-24 days
• As the diestrus (luteal) phase begins, the bitch is no longer receptive to mating (roughly 2 months)
• Vulva decreases in size, but may continue to see some vaginal discharge for the first few days of diestrus
• +/- Mammary development with lactation in late diestrus
• Low estradiol, elevated progesterone, and presence of Cl regardless of pregnancy status
• Cytology >50% parabasal and intermediate epithelial cells, where WBC is present even abundant in early diestrus, and reduced RBC relative to proestrus
• Anestrus lasts roughly four months where the bitch is not receptive to mating
• Vulva continues to reduce in size
• Estradiol and progesterone levels are low
• FSH and LH pluse increase in late anetrus
• Antral follicles in various stages of development/atresia. CLs are regressing
• Cytology consists of >90 parabasal/intermediate epithelial cells, few extracellular bacteria and WBCs, and no RBCs

Oocyte Maturation

• Canine ovulation is unique
• Ovulation occurs 2 days after the LH surge
• Eggs ovulate as primary oocytes in prophase I (immature)
• Requires ~48-60 hrs to complete metaphase II
• Eggs are only mature 4 days after LH surge
• Eggs remain fertile for 48-72 hrs following maturation
• If pregnant, P4 from CL inhibits GnRH to prevent excess follicles and maintain pregnancy
• If not pregnant, CL regresses, lifting the negative feedback and restarting the cycle

Canine Estrus Cycle Tools

• There are 3 tools veterinarians can use to understand the hormones and the canine estrous cycle; vaginal cytology, serum progesterone and luteinizing hormone (LH) testing

Vaginal Cytology

• Is a useful tool for vets when evaluating progression of estrus cycle
• It is a bioassay for estrogen levels, that is inexpensive and easily performed when bitch is in estrus
• Sample vagina (not vestibule) using moistened cotton swab; part lips, advance dorsally and cranially SLOW
• Spin the swab to collect cellular material
• Roll sample onto slide in unidirectional fashion, and diff-quick stain
• Four phases of cells: non-cornified parabasal and intermediate, and cornified superficial/anucleate

Cell Types

• Parabasal cells are seen in diestrus and anestrus and are not uncommon in early proestrus - conspicuously absent in estrus
• Intermediate cell size is small-round/oval with a moderately sized nuclei or large- slighlty polygonal shape with large nucleus/cytoplasm ratio, and is seen in proestrus
• Superficial cell's appear early in cornification and are seen in late proestrus and estrus - cells appear polygonal or cornflake shape with undefined/small nucleus.
• Anucleate Cells have full cornification and are seen in estrus. Cells appear polygonal or cornflake shape with nucleus being absent
• Neutrophils are often seen in diestrus and during copulation, can be seen in proestrus when red blood cells are present. Important note that the vagina isn't normally sterile
• Bacteria is typically mixed with extracellular bacteria and should evaluate any intracellular bacteria in neutrophils
• Vaginal cytology is a bioassay for estrogen levels

Serum Progesterone (ng/mL) Concentrations & Best Breeding Days

• <1 Proestrus, at +4 days best breeding days in fertile window

• 1.0-1.9 ng/mL At or near LH surge, at +3 days

• 2.0-3.9 ng /mL LH Surge has already occured, at +2 days

• 4.0-10 ng/mL At or near ovulation, at ovulation

• 10 ng /mL Ovulation has occured, immediately

Canine Anatomy of the Dog

• Penis is musculocavernous tissue which contains an os penis that aids in intromission
• The Bulbus Glandis is at the base of the penis and is important because it locks the penis in the female
• The elasticity at the base of the penis allows for a 180-degree turn for a copulatory lock.
• Dogs will often start by mounting to copulate and then turn butt to butt

Anatomy of the Prostate

• Is the only accessory sex gland in the dog
• It is located retroperitoneal and bilobed
• It surrounds the urethra at the neck of the bladder
• Is required for most ejaculatory volume

Anatomy of the Testicles

• Located in an oblique position in the scrotum with the long axis being dorso-caudal
• Head of the epididymis is cranially positioned, while the distal tail is caudally positioned
• Testicular descent into the scrotum happens within the first week of life, reaching their final position at about a little over a month of age.

Puberty and Sexual Behavior

• Puberty range varies by breed: but commonly at 1yr

Types of Behaviors in Males

• Secondary, including: Humping, marking and leg lifting

Coitus Behavior

• Penis enters the vagina prior to full erection
• Os penis provides rigidity and the vulva deflects the prepuce
• Penis then becomes fully erect and causes the bulbus glandis to swell during erection creating a copulatory lock
• Tie lasts for 10-15 minutes
• Do not attempt to separate copulatory dogs if they get into that state.

Semen Analysis Equipment and supplies

• Teaser Bitch and/or Scent Swab
• Artificial Vagina (AV)
• Collection tube
• Gloves (No Lube)
• Calm and Quiet Space
• good Footing
• Bitch, somebody collecting it, and somebody actually stimulating the dog..

Evaluation

• Note look, color, opacity and volume

Total Sperm Count

• Concentration (per mL) x volume = total sperm/ejaculate
• Ideally 10 million sperm/lb body weight.

Morphology

• Evaluate Individual sperm shape
• Fixation and staining(eosin-nigrosin)
• Greater than 70% normal morphology

Bitch's Ovulatory Cycle

• Is based on making a decision on things the cycle the stud, processing of semen and breeding time
• Types of Cycles- Natural and Artificial
• Fresh and Chilled are vaginal Trans- Cervical
• Frozen requires Intrauterine / surgical

Natural Breeding time

• Bred every other day from 10-14day cycles
• Challenges include injuries, anatomy issues and transport issues
• Stud dog can be a really helpful guide in terms of timing.
• When a bitch is in estrus, she will stand for that male. And so when she's willing to stand, you can breed them every other day
  • Between day 10 to 14 of the cycle.

Artificial Insemination

• Semen is deposited in virginial tract using by a pipette or catheter and takes only 10-15 minutes
  • Relatively inexpensive ($200-250)
• Transcervical insemination needs direct deposit into uterine body, catheterizing the cervix, little sedation and requires only 10-30 minutes
  • Mofa Scope is the manufacturer of the necessary rigid fiber optic endoscope
  • Rigid fiber optic instills semen into the uterus via the cervix for $600-700.
  • A surgical method is an option that cost more due to it requiring anesthesia.
• Para-cervical insemination is also an option
• To do so, the semen is deposited at the cervix when it can't be instilled due to the cervix itself.

Pregnant Physiology

• Fertilization Occurs in uterine tubes
• Transuterine migration allows even spread of embryo
• Canine Embryos implant 16-18 days following LH surge

Types of Placentation

• Canine embryos are endotheliochorial and zonary

Radiography during pregnancy

• Fetal skeleton mineralization = 45 gestation days
• Fetal Counts start at 55-60 days

Progesterone during Canine pregnancy

• Only Comes for Corpus luteum and doesn't change the mothers

Inaccuracies of Gestation (63Lh Surge 65Lh ovulation)

• Calculated dates are variable ranging from 55-67
• Estimates have a due date from 57 dyetsrus, Day 1 if you know

Pregnancy Diagnosis options

• Palpation best at 31 days but doesn't indicate viability
• Ultrasound Is recommended at 25-28 days and it viable by 35 days
• Radiographs shows fetal at 45 and to get more a ccurat count
• Relaxin tests blood early but are $$$ 2

What to do in clinical cases to get best Parturition

• Predicting the Onset by a few inaccurate methods
  • Temp drop 2 degrees (97.98temp0 relates serum progesterone level
  • Relaxation of gravitated uterus and mammary development

First signs of Parturition to look for in the initial onset

• Temperature drop and rebound (Myometrial contractions, cervical dilation and panting
  • Phase 2 begins with Contractions and puppies should be born 30-60 minutes with the cervix fully dilated now
  • Phase 3 should pass after the placentas then may alternate with phase too with entire delivery taking to at least 12 hrs

Hormone for life

• Role of hormones with pyometra
• The ovarian remnants syndrome
• Prostatic and hormones in general
• Spay and neuter Guidelines

Pyometra

• Is the infection of the Uterine with Pus, mostly in Bitch, hormone induced disease exasserbated Ecoli
• Cyst formation and CEH
• The progesterone level closes cervix reducing contractions thus closing closed pyometras
• With that the patients typically present older then 8 years

How to treat Pyometra patients

• Treat will have to always Spay first then medical management option by using ALLIZIN

Ovarian remnant Syndrome.

• Is for when tissue still returns
• So then if the patients signs is estrus.

ORS

• To see again, look if its related behavior and other
• Do a cytology and progesterone tests
• Can test after with the test

Prostatic Hyperplasia

• Common disease in intact males in dogs
• Is secondary and the most common is older dogs
• Non pain in routine but with no
  • thick capsule putting pressure outside

In Conclusion for Life

• Most things are known how well to change our physiology and understand our gonadectomy 8b

Canine Ovulation

• The phenomenon is called pre-ovulatory follicular luteinization -- really unusual because there is an increase in progesterone prior to ovulation
  • Also the individual granulosa cells in the developing follicle luteinize little by little
  • Is endocrinologically detectable in serum prior to ovulation even prior to LH

If we are comparing it to serum progesterone levels

• ~0.2 ng/mL- 1.5ng are pre vulatory follicular luteinization
• ~At the 2 ng mark, an LH surge happens
  • What follows causes the effect on follicular Leutinization, increasing progesterone Two days post LH have ovulation which is caused by P4 double affecting the process