Equine - Mare Infertility: Non-infectious

Question 1

What are the non-infectious causes of infertility?

Answer 1

Mare management/abnormal cyclicity, stallion issues, anatomic abnormalities, ovarian tumors, and uterine fibrosis/endometrial cysts

Question 2

Which mares are at a higher risk of infertility?

Answer 2

Older mares

Question 3

Why are older mares at a higher risk of infertility?

Answer 3

They cycle less after 20 years - longer transitional periods, longer follicular phases, and fewer ovulations/year

Question 4

When may mares stop cycling?

Answer 4

throughout the breeding season

Question 5

If a mare is cycling normally, uterine fluid is present, and she is infertile, what is on your ddx list?

Answer 5

Endometritis, maiden mare cervix (tight), and tract patency (persistent hymen, segmental aplasia, stricture/adhesion)

Question 6

If a mare is cycling normally, uterine fluid is absent, and she is infertile, what is on your ddx list?

Answer 6

there is a stallion issue, improper breeding timing, blocked oviducts, uterine pathology, or possibly CL issue

Question 7

If a mare fails to return to estrus, what is on your ddx list?

Answer 7

pregnancy, endometrial cups, transitional period, silent heats, no teasing ability, foal present, dominant mare in the pasture

Question 8

If a mare has a prolonged/persistent estrus(shortened luteal activity), what is on your ddx list?

Answer 8

submissive mare, ovarian pathology, perception by owners (mark on calendar), short cycling

Question 9

What is the luteal phase like if a mare has a failure to return to estrus?

Answer 9

there is a prolonged luteal phase of greater than 17 days

Question 10

What is the incidence of prolonged luteal activity in a mare?

Answer 10

up to 18% of mares

Question 11

What is the etiology of prolonged luteal activity?

Answer 11

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

Question 12

How is prolonged luteal activity diagnosed?

Answer 12

ultrasound or serum progesterone assay

Question 13

What will you see if a mare has prolonged luteal activity on ultrasound?

Answer 13

There will be CLs present on one or both ovaries for more than 17 days post-ovulation

Question 14

What will a serum progesterone assay show if there is prolonged luteal activity?

Answer 14

progesterone is elevated over 2 ng/ml for greater than 14 days

Question 15

How is prolonged luteal activity treated?

Answer 15

exogenous prostaglandin (Lutalyse and Cloprostenol) IM SID for 1-2 days

Question 16

What will happen to the luteal phase if a mare is having prolonged estrus?

Answer 16

the luteal phase will be less than 13 days (typically 7-11) - premature luteolysis

Question 17

What is the etiology of shortened luteal activity?

Answer 17

prostaglandin production associated with uterine inflammation or bacterial toxins

Question 18

How is shortened luteal activity diagnosed?

Answer 18

ultrasound, endometrial cytology and cultutre, +/- biopsy

Question 19

How is shortened luteal activity treated?

Answer 19

treat the underlying cause

Question 20

What are the clinical signs of persistent estrus?

Answer 20

Constantly showing behavior interpreted as estrus and interfering with mares funciton, behavioral changes, signs of agitation, discomfort or submission

Question 21

What behaviors are reported with persistent estrus?

Answer 21

irritable, kicking, leaning, striking, urinating, wringing tails

Question 22

What are the ddx for persistent estrus?

Answer 22

seasonal transition, pregnancy, ovarian dysgenesis, granulosa cell tumor, vaginal inflammation due to pneumovagina, urethral or bladder abnormalities

Question 23

How is persistent estrus diagnosed?

Answer 23

transrectal palpation and ultrasound, and vaginal examination

Question 24

What can failure to ovulate be a cause of and when does it commonly occur?

Answer 24

It can be a cause of anestrus and it commonly occurs in transition periods into and out of breeding seasons

Question 25

Characterize anovulatory follicles.

Answer 25

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

Question 26

What is follicular atresia?

Answer 26

The break down of the ovarian follicles - they fail to emerge as a dominant follicle

Question 27

What can cause follicular atresia?

Answer 27

ovarian hypoplasia, ovarian cysts, infections, and malnutrition

Question 28

What is the treatment for follicular atresia?

Answer 28

time

Question 29

What are some potential stallion issues that can lead to fertility?

Answer 29

poor semen quality/quantity, not actually breeding, venereal diseases

Question 30

How are stallion issues diagnosed?

Answer 30

history/clinical signs and breeding soundness examination

Question 31

What congenital defects of the uterine tube can lead to infertility?

Answer 31

segmental aplasia with hydrosalpinx

Question 32

What congenital defects of the uterus can lead to infertility?

Answer 32

hypoplasia, segmental aplasia, and duplication

Question 33

What congenital defects of the cervix can lead to infertility?

Answer 33

hypoplasia, segmental aplasia, hyperplasia, and duplication

Question 34

What congenital defects of the vagina can lead to infertility?

Answer 34

persistent hymen and vestibular-vaginal hypoplasia

Question 35

What is a persistent or imperforate hymen and what population is it most common in?

Answer 35

Thickened tissue at the vestibulovaginal junction +/- prolapse and it is common in maiden mares

Question 36

What is the treatment for persistent or imperforate hymen?

Answer 36

You may need to do surgical correction depending on the amount of tissue - otherwhise nothing

Question 37

What are some acquired defects that can lead to infertility?

Answer 37

Adhesions due to foaling trauma or metritis/endometritis

Question 38

What are some iatrogenic defects that can lead to infertility?

Answer 38

adhesions due to chlorhexidine and baytril

Question 39

What is the most common uterine neoplasia?

Answer 39

Leiomyoma

Question 40

What other neoplasias can occur in the uterus?

Answer 40

Leiomyosarcoma, rhabdomyosarcoma, lymphosarcoma, and adenocarcinoma

Question 41

What is the normal chromosomal number in a mare?

Answer 41

64 or 32 pairs - 64 XX

Question 42

What are the chromosomal defects that can lead to infertility?

Answer 42

Turner's Syndrome and 64XY

Question 43

What is the most common chromosomal abnormality in mares?

Answer 43

Truner's syndrome

Question 44

What is Turner's syndrome characterized by?

Answer 44

small ovaries, poorly developed uterus, and permanent anestrous

Question 45

What does 64XY cause and what is it due to?

Answer 45

sex reversal or testicular feminization - due to a missing SRY gene

Question 46

What is intersexuality?

Answer 46

It is true or pseudo-hermaphroditism

Question 47

What does intersexuality look like physically?

Answer 47

testicular tissue is present instead of ovaries

Question 48

Why does true or psuedo-hermaphroditism happen?

Answer 48

there is a failure to form normal internal female tract resulting in blind-ended vagina

Question 49

What is the cyclicity and behavior of a mare with intersecuality?

Answer 49

There is absence of cyclicity and stallion-like behavior

Question 50

When is intersexuality suspected?

Answer 50

early in life due to changes in the external genitalia

Question 51

What are the behavioral changes associated with granulosa (theca) cell tumor?

Answer 51

persistent anestrus, aggressive or stallion-like behavior, constant or erratic estrus

Question 52

Are granulosa cell tumors reported in foals?

Answer 52

yes

Question 53

How are granulosa cell tumors diagnosed?

Answer 53

transrectal palpation, transrectal ultrasound, and endocrinology

Question 54

How will the ovary feel on transrectal palpation if there is a granulosa cell tumor present?

Answer 54

the ovulation fossa is not present and the contralateral ovary is inactive and small

Question 55

What will the ovary appear like on ultrasound if there is a granulosa cell tumor?

Answer 55

There is no pathognomonic appearance - the most common appearance is multi-cystic structure - can also be unilocular cysts or solid throughout

Question 56

What will endocrinology results be if a mare has a granulosa cell tumor?

Answer 56

elevated inhibin, elevated testosterone, variable estradiol elvels, and elevated anti-mullerian hormone

Question 57

How are granulosa cell tumors treated?

Answer 57

surgical removal of the affected ovary

Question 58

Can mares resume cyclicity if an affected granulosa cell tumor is removed?

Answer 58

yes - 75% of mares will resume cyclicity on the remaining ovary within 1-2 years following removal

Question 59

Aside from granulosa cell tumors, what other ovarian tumors can mares get?

Answer 59

teratoma and serous cystadenomas

Question 60

How do teratomas affect cyclicity?

Answer 60

it may disrupt cyclicity

Question 61

True or False: Teratomas are difficult to diagnose?

Answer 61

True - ovarian enlargement is less pronounced and US findings are unremarkable

Question 62

What are serous cystadenomas?

Answer 62

multiple large cystic structures resembling normal follicles on transrectal palpation and ultrasound

Question 63

Do serous cystadenomas affect cyclicity?

Answer 63

no, but there are elevated testosterone levels

Question 64

What is the etiology of ovarian dysgenesis?

Answer 64

There are defects with the X chromosome - 63 XO, 65 XXX, or XY

Question 65

What history is related with ovarian dysgenesis?

Answer 65

May be non-specific and never foaled or been prognant

Question 66

What clinical signs are associated with ovarian dysgenesis?

Answer 66

They present for anestrus, erratic estrus, or constant estrus and have a shorter stature with increased hind limb angulation

Question 67

What is erratic estrus or constant estrus in mares with ovarian dysgenesis due to?

Answer 67

the lack of progesterone

Question 68

How is ovarian dysgenesis diagnosed?

Answer 68

transrectal palpation and ultrasound, and karyotyping

Question 69

What will you see if a mare has ovarian dysgenesis on ultrasound?

Answer 69

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

Question 70

What are the ddx for ovarian dysgenesis?

Answer 70

seasonal anestrus, old mares, and mares with severe energy imbalance due to starvation or diseae

Question 71

What is the treatment associated with ovarian dysgenesis?

Answer 71

none

Question 72

What are the complications of endometrial cysts?

Answer 72

interfere with pregnancy, embryonic movement and fixation, and delivery of placental nutrition

Question 73

When is treatment for endometrial cysts necessary?

Answer 73

when the mare fails to conceive or suffers early embryonic loss for undiagnosed reasons

Question 74

What is the treatment for endometrial cysts?

Answer 74

cautery, rupture via biopsy instrument, or ablation via laser