Lecture 9: Infertility in the mare

Question 0

what is a persistent corpus luteum caused by?

Answer 0

• if a second ovulation (diestrual ovulation) occurs 1 - 4 days before endogenous PGF release (day 15 - 16). an immature CL will not respond to PGF release and continues to produce progesterone
• failure to secrete PGF
• reduce PGF secretion due to chronic uterine infection
• early embryonic death after maternal recognition of pregnancy

Question 1

describe the spring transition

Answer 1

non-ovulatory
increased day length results in increased secretion of GnRH which causes an increase in FSH but not LH
- this results in follicular activity without ovulation.
- may see erratic prolonged estrus periods

Question 2

how do you treat a persistent CL?

Answer 2

PGF2alpha

Question 3

what is the effect of artificial lighting

Answer 3

moves the time of the vernal transition - but does not shorten it beyond physiological 6 - 8 weeks

expose mares to 16 hours of light and 8 hours of dark

Question 4

Progesterone (regumate): effect on infertility seasonality - management

Answer 4

it suppresses the release of LH

• used for estrus regulation during the transition
• treat for 10-14 days, withdrawal results in LH release and estrus beginning 4-5 days later.
• ovulation occurs 10 days after cessation of treatment

Question 5

granulosa-theca cell tumor characteristics

Answer 5

• main ovarian tumor
• hormonally active
• unilateral
• benign

Question 6

granulosa-theca cell tumor: clinical signs

Answer 6

behavioral changes: stallion-like, anestrus, persistent estrus
unilateral enlarged ovary
small, inactive opposite ovary

Question 7

granulosa-theca cell tumor: Dx

Answer 7

clinical signs: +/- enlarged, firm, no ovulation fossa
ultrasound
serum hormone assays: inhibin, testosterone, progesterone, AMH

Question 8

granulosa theca cell tumor: effect of inhibin

Answer 8

elevated in 90% - responsible for the inactivity of the contralateral ovary

Question 9

granulosa theca cell tumor: effect of testosterone

Answer 9

elevated in 50% - responsible for stallion-like behavior

Question 10

granulosa theca cell tumor: progesterone (baseline)

Answer 10

below 1ngml since normal follicular development, ovulation and CL formation do not occur

Question 11

granulosa theca cell tumor: effects of AMH

Answer 11

high serum concentrations

its the MOST SENSITIVE test for granulosa theca cell tumors

Question 12

granulosa theca cell tumor: tx

Answer 12

surgery - most cycle within 2 - 12 months

Question 13

what other ovarian tumors are there?

Answer 13

cystadenomas, dysgerinoma, teratoma

Question 14

two types of anovulatory follicles

Answer 14

follicular - lumen remains filled with follicular fluid

luteal - lumen gets infiltrated with echogenic particles –> fibrin strands –> lutenized tissue

Question 15

how do you dx and tx anovulatory follicles?

Answer 15

dx: measure plasma progesterone 5 -7 days after hte mare stops showing signs of estrus
tx: PGF2alpha - but a good number will repeat the process next cycle

Question 16

abnormalities of external genitalia

Answer 16

cervical lacerations, pneumovagina, urovagina

Question 17

cervical laceration dx and tx

Answer 17

dx: vaginoscopy and digital exam
tx: sx

Question 18

pneumovagina: cause of occurrence and tx

Answer 18

cause: due to secondary changes in perineal conformation - cranio-ventral displacement of the tract, loss of integrity of the vestibulovaginal sphincter, loss of integrity of the vulvar labia
tx: caslick’s vulvoplasty

Question 19

urovagina: occurrence and tx

Answer 19

occurrence: when cranial vagina slopes cranioventrally. urine collects in teh anterior vagina where it is spermicidal and may cause cervicitis and endometritis
tx: sx

Question 20

sextually transmitted diseases

Answer 20

contagious equine metritis (CEM) caused by tyorella equigenitalis

equine herpes 3

pseudomonas spp. Klebsiella

equine viral arteritis

Question 21

causes of persistent uterine infection

Answer 21

break-down of external barriers
contamination
compromised uterine defense

Question 22

how are STDs and persistent uterine infection dx?

Answer 22

vaginal discharge culture and cytology

Question 23

how are STDs and persistent uterine infection tx?

Answer 23

treat underlying breakdown of uterine defense (cervical laceration, pneumovagina with caslicks)

intrauterine infusions with abx

uterine lavage

Question 24

** persistent breeding-induced endometritis (PBIE) **

Answer 24

• sperm cause an inflammatory reaction which is a normal physiological reaction that serves to clear the uterus from excess sperm and contaminants
• may develop into a pathological condition (PBIE) in “susceptible” mares
• interferes with embryo survival if not cleared when the embryo enters the uterus

Question 25

** PBIE “susceptible mares” **

Answer 25

those with impaired myometrial activity and delayed uterine clearance

Question 26

** does pyometra cause systemic illness? **

Answer 26

** NO! **

Question 27

How is PBIE diagnosed and tx?

Answer 27

dx: accumulation of fluid within the uterine lumen for > 12 hours after breeding
tx: assist the uterus to clear the inflammation via uterine lavage or oxytocin

Question 28

how do pyometras occur?

Answer 28

often a result of impaired uterine drainage resulting from cervical adhesions following a dystocia

Question 29

how are pyometras dx and tx?

Answer 29

dx: ultrasound
tx: uterine drainage and lavage and hysterectomy

Question 30

what are two types of endometrial cysts?

how are they tx?

Answer 30

glandular: small < 10mm - result from periglandular fibrosis

lymphatic cysts: larger, can reach several cm, lacunae thought to originate from itnerference with normal lymph drainage of genital tract\

tx = often untreated, but can be removed with laser sx

Question 31

what can often be misdiagnosed as an early pregnancy?

Answer 31

endometrial cysts