Equine - Mare Infertility: Non-infectious Flashcards
What are the non-infectious causes of infertility?
Mare management/abnormal cyclicity, stallion issues, anatomic abnormalities, ovarian tumors, and uterine fibrosis/endometrial cysts
Which mares are at a higher risk of infertility?
Older mares
Why are older mares at a higher risk of infertility?
They cycle less after 20 years - longer transitional periods, longer follicular phases, and fewer ovulations/year
When may mares stop cycling?
throughout the breeding season
If a mare is cycling normally, uterine fluid is present, and she is infertile, what is on your ddx list?
Endometritis, maiden mare cervix (tight), and tract patency (persistent hymen, segmental aplasia, stricture/adhesion)
If a mare is cycling normally, uterine fluid is absent, and she is infertile, what is on your ddx list?
there is a stallion issue, improper breeding timing, blocked oviducts, uterine pathology, or possibly CL issue
If a mare fails to return to estrus, what is on your ddx list?
pregnancy, endometrial cups, transitional period, silent heats, no teasing ability, foal present, dominant mare in the pasture
If a mare has a prolonged/persistent estrus(shortened luteal activity), what is on your ddx list?
submissive mare, ovarian pathology, perception by owners (mark on calendar), short cycling
What is the luteal phase like if a mare has a failure to return to estrus?
there is a prolonged luteal phase of greater than 17 days
What is the incidence of prolonged luteal activity in a mare?
up to 18% of mares
What is the etiology of prolonged luteal activity?
diestral follicles ovulate after day 10 of diestrus and a new CL is too immature to respond to endogenous prostaglandin, lutenized hemorrhagic follicle, severe endometrial damage with impairment of prostaglandin production, idiopathic
How is prolonged luteal activity diagnosed?
ultrasound or serum progesterone assay
What will you see if a mare has prolonged luteal activity on ultrasound?
There will be CLs present on one or both ovaries for more than 17 days post-ovulation
What will a serum progesterone assay show if there is prolonged luteal activity?
progesterone is elevated over 2 ng/ml for greater than 14 days
How is prolonged luteal activity treated?
exogenous prostaglandin (Lutalyse and Cloprostenol) IM SID for 1-2 days
What will happen to the luteal phase if a mare is having prolonged estrus?
the luteal phase will be less than 13 days (typically 7-11) - premature luteolysis
What is the etiology of shortened luteal activity?
prostaglandin production associated with uterine inflammation or bacterial toxins
How is shortened luteal activity diagnosed?
ultrasound, endometrial cytology and cultutre, +/- biopsy
How is shortened luteal activity treated?
treat the underlying cause
What are the clinical signs of persistent estrus?
Constantly showing behavior interpreted as estrus and interfering with mares funciton, behavioral changes, signs of agitation, discomfort or submission
What behaviors are reported with persistent estrus?
irritable, kicking, leaning, striking, urinating, wringing tails
What are the ddx for persistent estrus?
seasonal transition, pregnancy, ovarian dysgenesis, granulosa cell tumor, vaginal inflammation due to pneumovagina, urethral or bladder abnormalities
How is persistent estrus diagnosed?
transrectal palpation and ultrasound, and vaginal examination
What can failure to ovulate be a cause of and when does it commonly occur?
It can be a cause of anestrus and it commonly occurs in transition periods into and out of breeding seasons
Characterize anovulatory follicles.
Large follicles which fail to rupture and ovulate, fill with blood and persist as hematomas over a number of cycles (AHF), and presence is further complicated with their ability to secrete progesterone
What is follicular atresia?
The break down of the ovarian follicles - they fail to emerge as a dominant follicle
What can cause follicular atresia?
ovarian hypoplasia, ovarian cysts, infections, and malnutrition
What is the treatment for follicular atresia?
time
What are some potential stallion issues that can lead to fertility?
poor semen quality/quantity, not actually breeding, venereal diseases
How are stallion issues diagnosed?
history/clinical signs and breeding soundness examination
What congenital defects of the uterine tube can lead to infertility?
segmental aplasia with hydrosalpinx
What congenital defects of the uterus can lead to infertility?
hypoplasia, segmental aplasia, and duplication
What congenital defects of the cervix can lead to infertility?
hypoplasia, segmental aplasia, hyperplasia, and duplication
What congenital defects of the vagina can lead to infertility?
persistent hymen and vestibular-vaginal hypoplasia
What is a persistent or imperforate hymen and what population is it most common in?
Thickened tissue at the vestibulovaginal junction +/- prolapse and it is common in maiden mares
What is the treatment for persistent or imperforate hymen?
You may need to do surgical correction depending on the amount of tissue - otherwhise nothing
What are some acquired defects that can lead to infertility?
Adhesions due to foaling trauma or metritis/endometritis
What are some iatrogenic defects that can lead to infertility?
adhesions due to chlorhexidine and baytril
What is the most common uterine neoplasia?
Leiomyoma
What other neoplasias can occur in the uterus?
Leiomyosarcoma, rhabdomyosarcoma, lymphosarcoma, and adenocarcinoma
What is the normal chromosomal number in a mare?
64 or 32 pairs - 64 XX
What are the chromosomal defects that can lead to infertility?
Turner’s Syndrome and 64XY
What is the most common chromosomal abnormality in mares?
Truner’s syndrome
What is Turner’s syndrome characterized by?
small ovaries, poorly developed uterus, and permanent anestrous
What does 64XY cause and what is it due to?
sex reversal or testicular feminization - due to a missing SRY gene
What is intersexuality?
It is true or pseudo-hermaphroditism
What does intersexuality look like physically?
testicular tissue is present instead of ovaries
Why does true or psuedo-hermaphroditism happen?
there is a failure to form normal internal female tract resulting in blind-ended vagina
What is the cyclicity and behavior of a mare with intersecuality?
There is absence of cyclicity and stallion-like behavior
When is intersexuality suspected?
early in life due to changes in the external genitalia
What are the behavioral changes associated with granulosa (theca) cell tumor?
persistent anestrus, aggressive or stallion-like behavior, constant or erratic estrus
Are granulosa cell tumors reported in foals?
yes
How are granulosa cell tumors diagnosed?
transrectal palpation, transrectal ultrasound, and endocrinology
How will the ovary feel on transrectal palpation if there is a granulosa cell tumor present?
the ovulation fossa is not present and the contralateral ovary is inactive and small
What will the ovary appear like on ultrasound if there is a granulosa cell tumor?
There is no pathognomonic appearance - the most common appearance is multi-cystic structure - can also be unilocular cysts or solid throughout
What will endocrinology results be if a mare has a granulosa cell tumor?
elevated inhibin, elevated testosterone, variable estradiol elvels, and elevated anti-mullerian hormone
How are granulosa cell tumors treated?
surgical removal of the affected ovary
Can mares resume cyclicity if an affected granulosa cell tumor is removed?
yes - 75% of mares will resume cyclicity on the remaining ovary within 1-2 years following removal
Aside from granulosa cell tumors, what other ovarian tumors can mares get?
teratoma and serous cystadenomas
How do teratomas affect cyclicity?
it may disrupt cyclicity
True or False: Teratomas are difficult to diagnose?
True - ovarian enlargement is less pronounced and US findings are unremarkable
What are serous cystadenomas?
multiple large cystic structures resembling normal follicles on transrectal palpation and ultrasound
Do serous cystadenomas affect cyclicity?
no, but there are elevated testosterone levels
What is the etiology of ovarian dysgenesis?
There are defects with the X chromosome - 63 XO, 65 XXX, or XY
What history is related with ovarian dysgenesis?
May be non-specific and never foaled or been prognant
What clinical signs are associated with ovarian dysgenesis?
They present for anestrus, erratic estrus, or constant estrus and have a shorter stature with increased hind limb angulation
What is erratic estrus or constant estrus in mares with ovarian dysgenesis due to?
the lack of progesterone
How is ovarian dysgenesis diagnosed?
transrectal palpation and ultrasound, and karyotyping
What will you see if a mare has ovarian dysgenesis on ultrasound?
small, cylindrical ovaries with no follicular activity and the remainder of the reproductive tract is normal but immature due to the lack of gonadal steroids
What are the ddx for ovarian dysgenesis?
seasonal anestrus, old mares, and mares with severe energy imbalance due to starvation or diseae
What is the treatment associated with ovarian dysgenesis?
none
What are the complications of endometrial cysts?
interfere with pregnancy, embryonic movement and fixation, and delivery of placental nutrition
When is treatment for endometrial cysts necessary?
when the mare fails to conceive or suffers early embryonic loss for undiagnosed reasons
What is the treatment for endometrial cysts?
cautery, rupture via biopsy instrument, or ablation via laser
